1 Chapter 12 Raspberries C. E. Finn 1, J. F. Hancock 2 1 USDA-ARS, Horticultural Crops Research Unit, 3420 NW Orchard Avenue, Corvallis, Oregon 97330, U.S.A. 2 Department of Horticulture, 342C Plant and Soil Sciences Building, Michigan State University, East Lansing, Michigan 48824, U.S.A. E-mail: finnc@hort.oregonstate.edu Abstract All raspberry breeders are interested in improving fruit quality and increasing the efficiency of fruit production. The development of primocane fruiting cultivars with excellent shipping quality has allowed major raspberry industries to emerge in non-traditional areas such as California. An increased interest in fruit chemistry, particularly anthocyanins, has led to many studies determining the inheritance of these compounds. Progress towards resistance to major diseases such as Phytophthora root rot has been made through greater understanding of the inheritance of these traits, and the use of novel and traditional germplasm resources. Black raspberry breeding efforts have been greatly increased in the early 21st Century in response to increased disease pressure and raised consumer awareness of the high levels of antioxidants in their fruit. A genetic linkage map of red raspberry ('Glen Moy' x 'Latham') has been constructed and used to search for QTL associated with cane spininess, root sucker density and root sucker spread. Transformation was used to develop a red raspberry cultivar with resistance to Raspberry bushy dwarf virus, although it was not commercialized. 12.1 Introduction The most popular raspberry species grown commercially in temperate climates are Rubus idaeus L. (red raspberries) and R. occidentalis L. (black raspberries). There are also limited acreages of yellow raspberries grown, which are mutations of red raspberries, and purple ones, which are hybrids of red and black raspberry genotypes. Another domesticated species, R. arcticus L., is important in Scandinavia. Several native species have a small niche in the world market including R. chamaemorus L. in Scandinavia, R. parvifolius L., R. niveus Thunb. and R. coreanus Miq. in China and R. phoenicolasius Maxim. in Japan (Finn 1999). Raspberries are most productive in regions with mild winters and long, moderate summers. The major production areas of red raspberries in North America are the Pacific Northwest (Oregon, Washington and British Columbia), California, the eastern US (New York, Michigan, Pennsylvania and Ohio) and rapidly expanding industries in Mexico and Guatemala. In Europe, red raspberries are grown to the largest extent in Serbia, Russia and Poland, with commercial production scattered all across the European Union. The value of the early season fresh market production in Spain is incredibly high, but their acreage is much less than the other countries listed. In the southern hemisphere, red raspberries are most widely grown in Chile and New Zealand. Raspberry canes are biennial with the first year canes being called primocanes and the second 2 year canes floricanes. Within the red raspberries there are two types of cultivars, the primocane (fall) fruiting and floricane (summer) fruiting. Floricane fruiting raspberries produce canes that are vegetative in the first year and in the second year they flower, fruit, die (floricanes) and are pruned out. Therefore, in a given planting, in a given year, there will be vegetative canes that will produce next year’s crop and fruiting canes. Some of the more popular cultivars of this type are 'Tulameen', 'Glen Ample', 'Meeker' and 'Willamette'. The primocane fruiting red raspberry cultivars produce fruit in the fall at the top of the current season’s primocanes and then again in the second year, if they are not pruned out. Some of the more popular cultivars of this type include 'Heritage', 'Caroline', 'Josephine', 'Amity', and 'Autumn Bliss' and the proprietary cultivars from companies like Driscoll’s (Watsonville). While it is easiest to cut the canes of these cultivars off at ground level each winter after recovering just the late-summer primocane crop, the canes are sometimes left to over-winter and produce a very early spring crop. Because these primocane fruiting types can be double cropped in this way, they are sometimes called “everbearing raspberries”. Black raspberry cultivars are typically floricane fruiting. The primocanes that emerge from the crown are tipped in commercial plantings to about 1 m tall to encourage branching. During the winter the branches are cut back to about 45 cm. The following year these canes become floricanes and produce the crop. In the Northwest, where there is a strong but small (600 – 700 ha) industry, nearly all the commercial crop is planted in 'Munger', a cultivar released in 1890. A couple of primocane fruiting black raspberries exist; the very old cultivar 'Ohio Everbearer' (Hedrick 1925) and 'Explorer' (U.S. Plant Patent 17,727) which was patented in 2007. Purple raspberries tend to have a great deal of “hybrid vigor” and are crown forming and floricane fruiting with large, soft fruit. They are generally considered to have only fair quality fresh but truly shine when they are processed. 'Brandywine' and 'Royalty' are mostly commonly listed by commercial nurseries. 12.2 Evolutionary biology and germplasm resources Raspberries are in the genus Rubus of the Rosaceae. There are 15 subgenera recognized within Rubus (USDA 2007) with the domesticated raspberries being found in the subgenus Idaeobatus. Idaeobatus contains about 200 wild species with nine sections. Almost all of the raspberry species are diploid (2n = 14), with a few triploid and tetraploid types (Thompson 1995a and b, Thompson 1997). Idaeobatus species are concentrated in northern Asia, but are also located in Africa, Australia, Europe and North America (Jennings 1988). The greatest diversity is found in southwest China, the likely center of origin of the subgenus. The major commercial taxa of raspberries share a considerable amount of inter-fertility. Rubus idaeus and R. strigosus are completely inter-fertile (Darrow 1920) and are often considered two subspecies of the same species. The cross of R. occidentalis x R. idaeus is only successful if R. occidentalis is used as the female parent, although bud pollination and heat treatment can help overcome this unilateral incompatibility (Hellman et al. 1982). At least 40 additional species in Idaeobatus have also been used in raspberry breeding, along with a few species in the Cylactis, Anoplobatus, Chamaemorus, Dalibardastrum, Malachobatus, and Rubus (Table 12.1). 3 Table 12.1. Sources of germplasm that breeders have attempted to incorporate into their breeding material. 2x = 2n = 14. (Sources – Jennings 1988, Ying et al. 1989, Jennings et al. 1991, Swartz et al. 1993, Thompson 1995a, Daubeny 1996, Finn et al. 2002a and b). Subgenus Idaeobatus Idaeobatus Idaeobatus Idaeobatus Idaeobatus Species R. biflorus Buch.-Ham ex Sm. R. chingii Hu R. cockburnianus Hemsl. R. corchorifolius L. R. coreanus Miq. Ploidy 2x Location China Important traits Low chilling requirement; resistant to drought, high temperature, leaf spot, cane spot 2x 2x 2x 2x China China China China High yield, vigorous, fresh and processed fruit quality High fruit numbers per lateral; ease of harvest; late ripening Earliness; disease resistance; good flavor Earliness; Vigor; Range of fruit colors (orange-black); resistant to aphids, cane blight, midge blight, spur blight, cane Botrytis, anthracnose, European raspberry beetle, powdery mildew, leaf spot, root rot Firm fruit with a bright, non-darkening red color; early ripening; resistant to fruit rot, cane Botrytis, cane midge, cane beetle, root lesion nematode, strong laterals; winter tolerance Vigor, low chilling requirement Very high drupelet count; Vigor Idaeobatus R. crataegifolius Bunge 2x China Idaeobatus Idaeobatus 2x 2x China China Idaeobatus R. ellipticus Sm R. eustephanos Focke ex Diels R. flosculosus Focke 2x China Idaeobatus R. glaucus Benth.z 4x S. America Idaeobatus 2x China Idaeobatus R. innominatus var. kuntzeanus (Hemsl.) L.H. Bailey (=R. kuntzeanus) R. hirsutus Thunb 2x China Idaeobatus R. idaeus L. 2x Europe Idaeobatus R. strigosus Michx. 2x N. America Idaeobatus R. innominatus S. Moore 2x China Idaeobatus R. lasiostylus Focke 2x China Idaeobatus R. leucodermis Douglas ex Torr. & A. Gray 2x W.N. America High fruit numbers per lateral; condensed fruit ripening; erect habit; vigorous; cane disease resistance Low chilling requirement; vigor; excellent fruit quality particularly aroma; large fruit size; small seeds and drupelets; extended production season; root rot resistance Low chilling requirement; resistant to drought, high temperature, leaf spot, cane spot, cane beetle Large size and bright red color; heat and high humidity tolerance; tolerant of fluctuating winter temperatures As the primary species in red raspberry background a tremendous source of untapped diversity for most traits As the primary species in red raspberry background a tremendous source of untapped diversity for most traits Vigor; late ripening; heat and humidity tolerance; high fruit numbers per lateral; productivity; erect plant habit; excellent fruit size Vigor; high drupelet count; large fruit size; ease of harvest; fruit cohesiveness/pubescence; foliar disease resistance; yellow rust resistance Productive; large fruit; vigor; potential source RBDV resistance; resistant to cane and leaf rust 4 Table 12.1. Continued. z Subgenus Idaeobatus Idaeobatus Species R. mesogaeus Focke R. niveus Thunb. Ploidy 2x 2x Idaeobatus R. occidentalis L. 2x E.N. America Idaeobatus R. parvifolius L. 2x,4x Japan, China, Australia Idaeobatus Idaeobatus R. phoenicolasius Maxim. R. pileatus Focke 2x 2x Japan Europe Idaeobatus Idaeobatus R. pungens Cambess. R. rosifolius Sm. 2x 2x Idaeobatus Idaeobatus R. sachalinensis Leveille R. spectabilis Pursh. 4x 2x Indonesia Asia, Australia E. Asia W.N. America Idaeobatus Idaeobatus R. sumatranus Miq R. trifidus Thunb. 2x 2x Asia Japan Anoplobatus Anoplobatus R. deliciosus Torr R. odoratus L. 2x 2x W.N. America E. N. America Anoplobatus R. parviflorus Nutt. 2x W.N. America Chamaemorus R. chamaemorus. L. 8x Rubus, Ursini R. ursinus Cham. et Schlecht Circumpolar/ Sub-arctic W.N. America 7-13x Location China India, Asia Important traits Resistant to cane blight, cane midge Vigor; fruit firmness; tolerance to heat and humidity, and cane and leaf disease; orange rust resistance, erect; good flavor; primocane fruiting; high number fruit/lateral; fruit rot resist, late ripening Progenitor species for black raspberry cultivars so wide degree of diversity may be available for black raspberry improvement. For red raspberry improvement: tolerance to heat and humidity; resistant to aphids, bud moth, leaf rollers, cane beetle, two-spotted spider mite, fruit rot; firm fruit; late-ripening floricane fruit Low chilling requirement; resistant to drought, high temperature, high humidity, leaf spot, cane spot, spider mite, root rot; some tolerance fluctuating winter temperatures; productive; fruit size Very early; resistant to cane and Japanese beetle, powdery mildew, root rot Fruit flavor; resistant to cane blight, cane midge, cane Botrytis, spur blight, fruit rot, root rot; low chilling Early ripening floricane fruit; winter hardiness; resistant to spur blight High drupelet count; tolerant to high temperature and humidity Hardiness, flavor; vigor, drupelet size Early floricane and primocane fruiting; condensed fruit ripening; fruit with a bright, nondarkening, red color; ease of harvest; resistant to root rot and aphids; erect growth High drupelet count; tolerant to root rot in greenhouse trials; primocane fruiting Foliar disease resistance; black fruit color Upright growth habit, drought tolerance; cold hardiness Early primocane ripening; self-supporting canes; resistant to raspberry midge, cane blight; winter hardiness Upright habit; large, well formed fruit; veinbanding mosaic virus resistance Excellent, aromatic flavor; high ascorbic acid content; thornlessness, winter hardiness Good fruit quality; early ripening; resistant to Verticillium wilt and Phytophthora root rot While classified by USDA-ARS in Idaeobatus, has also been designated as “natural inter-subgeneric hybrid” (Thompson 1995a, Williams et al. 1949) and has been more successfully used in hybrids with blackberry than raspberry (Finn et al. 2002b, HK Hall pers. comm.). 5 Finn and Knight (2002) found that almost all raspberry breeding programs devote energy to the evaluation and incorporation of species germplasm. In Europe, at least 16 species have been evaluated and used as sources of new traits. In North America, at least 58 species have been evaluated and used in breeding. The program at East Malling has long been particularly active in incorporating genes from European species (Jennings 1988, Knight 1993).The USDA-ARS program in Oregon has more recently focused on Asian species, as have the programs in Maryland, North Carolina, Washington and British Columbia (Finn et al. 1999b, Finn et al. 2002a and b). 12.3 History of improvement The European red raspberry, R. idaeus was first mentioned in the historical record by Pliny the Elder. He described it as “ida” fruit grown by the people of Troy at the base of Mount Ida. However, it is likely that these plants originally came from the Ide Mountains of Turkey, as raspberries were not native to Greece (Jennings 1988). Raspberries gradually grew in popularity over the centuries and by the 1500s, R. idaeus was cultivated all over Europe. In 1829, 23 cultivated varieties were listed by George Johnson in his “History of English Gardening”. The North American R. strigosus was introduced into Europe in the early 19th century and natural hybrids with R. idaeus, resulted in much advancement. In fact, most red raspberry cultivars dating from this period are hybrids of these two species (Daubeny 1983, Dale et al. 1989 and 1993). The first formal breeding work on raspberries was begun in North America; Darrow (1937) cites Dr. Brinkle of Philadelphia, Pennsylvania as the “first successful raspberry breeder of this country”. The most enduring cultivar from this early breeding period was 'Latham' which was introduced in 1914 by the Minnesota Fruit Breeding Farm and is still grown. Five early European cultivars played the dominant role in the breeding of red raspberries including, 'Pruessen', 'Cuthbert' and 'Newburgh', which are hybrids between the North American and European species, and 'Lloyd George' and 'Pyne’s Royal', which are pure R. idaeus. 'Lloyd George' has been a particularly important parent, being in the direct ancestry of 32 % of the North American and European cultivars in 1970 (Oydvin 1970). This cultivar contributed several important traits including primocane fruiting, large fruit size and resistance to the American aphid. Jennings (1988) speculates that the success of 'Lloyd George' hybrids “was possibly achieved because they combined the long-conical shape of 'Lloyd George' receptacle with the more rounded shape of the American raspberries”. A key example of such a hybrid is 'Willamette', which is a cross of 'Newburgh' x 'Lloyd George', and dominated the industry in western North America for over a half century. Many programs released red raspberry cultivars in the latter half of the 20th Century and into the 21st Century, but only a few programs stood out as particularly active. In the United Kingdom, the program at East Malling was responsible for the “Malling series”. A number of selections were made prior to World War II and released in the 1950s, 'Malling Promise', 'Malling Exploit' and the most successful, 'Malling Jewel' (Jennings 1988). This program continued to have an impact with the later release of 'Malling Admiral' as a late, high yielding genotype and most recently 'Octavia' (Finn et al. 2007). In addition to these floricane cultivars, the program has developed a number of very important primocane fruiting cultivars, with 'Autumn Bliss' being the most important. 6 Further north at the Scottish Crop Research Institute the “Glen series” was developed, the first being 'Glen Clova' in 1969. 'Glen Moy' and 'Glen Prosen', released in 1981, were the first spineless raspberries and both offered great improvements in fruit size and flavor. 'Glen Ample' released in 1994 became a standard for quality and yield throughout much of Europe and the program continues to be active with the recent release of 'Glen Doll' (Figure 12.1). Figure 12.1. 'Glen Doll', bred at the Scottish Crop Research Institute. The breeding programs in the Pacific Northwest of North America at Washington State University (WSU; Puyallup, Wash.), Agriculture and Agri-Foods Canada (AAFC; Agassiz, BC) and the U.S. Dept. of Agriculture-Agricultural Research Service in Oregon (USDAARS; Corvallis) benefited from many years of collaboration among one another and with the U.K. programs. The USDA-ARS’s releases from the mid 1900s, 'Willamette' and 'Canby', are still commercially important floricane cultivars. The recent release 'Coho' from that program has been widely planted for its high yields of IQF fruit (Finn et al. 2001). The USDA-ARS primocane fruiters 'Summit' and 'Amity' have been very important since their release and 'Summit' has found new life in the developing Mexican industry. 'Meeker', developed by WSU and released in the 1960s, is still the processing industry standard (Finn 2006). This program continues to be active and the newest releases 'Cascade Delight' and 'Cascade Bounty' are likely to become the standards for root rot tolerant cultivars (Moore 2004 and 2006, Moore and Finn 2007). The AAFC program has been one of the most prolific and important programs over the past 30 years. The breeders there took full advantage of germplasm exchanges with the U.K. and were very successful at identifying outstanding selections out of crosses between British Columbia selections and some of the “Glen series” particularly 'Glen Prosen' (Finn 2006). The 1977 releases 'Chilcotin', 'Skeena' and 'Nootka' had excellent fruit quality and high yields 7 for a fresh market berry. The program followed these releases with 'Chilliwack' in the mid 1980s and the incredibly important 'Tulameen' in 1989. 'Tulameen' set new standards for fresh market quality particularly flavor. This program remains active and the recent releases 'Esquimalt', 'Chemainus', 'Cowichan', and 'Saanich' are being widely planted (Kempler et al. 2005a and b, Kempler et al. 2006 and 2007). Elsewhere in the U.S., the New York Agricultural Experiment Station (Geneva) used their own primocane fruiting germplasm in combination with material such as 'Durham', developed in New Hampshire, to produce an excellent primocane fruiting germplasm pool that culminated with the release of 'Heritage' in 1969 and 'Ruby' ('Watson') in 1988 (Daubeny 1997). First viewed as a novelty, the primocane fruiting types became the standard in regions where cold winter temperatures caused considerable winter damage to canes of floricane fruiting raspberries. Later, private companies in California, such as Driscoll’s Strawberry Associates (Watsonville, Cal.) developed cultivars and whole new production systems where the plants were only in the ground 18 months to fuel the rapid expansion of the enormous California raspberry industry (Finn and Knight 2002). The importance of the University of Minnesota release 'Latham' has already been mentioned, but other releases from that program such as 'Chief' have been valuable in breeding programs for their root rot resistance. While the program was discontinued in the early 2000s, 'Redwing', released in 1987 has been a popular primocane cultivar where other cultivars cannot mature their crops in time before fall frosts (Daubeny 1997). The cooperative program centered at the University of Maryland, in cooperation originally with Virginia Tech University, Rutgers University, and the University of Wisconsin – River Falls, really hit their stride in the late 1990s and early 2000s with the release of the primocane fruiting 'Caroline', 'Anne', and 'Josephine'. The eastern North America black raspberry (R. occidentalis) was not cultivated until the 19th century, probably because of its abundance in the wild and the public’s preference for red raspberry (Jennings 1988). Purple raspberry cultivars were actually grown earlier in the 1820s as hybrids of black and red raspberries. The first known pure black raspberry cultivar was 'Ohio Everbearer' that was selected for its propensity to produce a significant fall crop (Jennings 1988). Hedrick (1925) listed 193 black raspberry cultivars in his “The Small Fruits of New York”, although most were wild selections. The breeding of black raspberries was slow to develop, with the first active breeding work being initiated in the late 1800s at the New York Agricultural Experiment Station at Geneva. The station continued as the primary center of research for much of the 20th Century (Slate 1934, Slate and Klein 1952, Ourecky and Slate 1966, Ourecky 1975), although significant work was also done by Drain (1952 and 1956) in Tennessee. In the late 20th Century, breeding efforts ebbed and only three cultivars were released. In the early 21st Century, black raspberry breeding efforts were renewed at the New York Agriculture Experiment Station and the U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) in Corvallis, Oregon. In Corvallis, Dossett (2007) evaluated black raspberry families from sibling families from crosses among cultivars and a North Carolina selection to assess variation and inheritance of vegetative, reproductive and fruit chemistry traits in black raspberry. In New Zealand, spinelessness from red raspberry has been transferred to black raspberry and resulted in the recent release of the spineless 'Ebony' (H.K. Hall, pers. comm.). 8 12.4 Current breeding efforts There are now 38 active red raspberry breeding programs in 21 countries, found mostly in Europe and North America. These programs have released at least 160 red raspberry cultivars over the last 30 years (Tables 12.2 and 12.3). In a survey conducted in 2001 by Finn and Knight (2002), raspberry breeders were found to be optimistic about their programs financial support, as most were able to maintain or expand their programs. Support came from a varied mix of federal, state, commodity and royalty support, with the government support generally decreasing. Table 12.2. Red raspberry breeding programs worldwide. Country Australia Bulgaria Canada British Columbia Nova Scotia Ontario Chile Chile Chile China Germany Hungary Italy Latvia Mexico Norway New Zealand Poland Romania Russia Serbia Serbia Sweden Turkey United Kingdom England England England Scotland U.S.A. California California Florida Maryland-Virginia Wisconsin Coop Program Maryland North Carolina Oregon Washington Washington Washington Location Inst. Horticultural Develop., Knoxfield, Victoria Kostinbrod Agriculture and Agri-Food Canada, Agassiz Agriculture and Agri-Foods Canada, Kentville University of Guelph, Guelph Hortifrut (Santiago) VBM (Santiago) INIA Beijing Institute of Pomology & Forestry, Beijing Freising-Weinhenstephan Small Fruit Research Station (Fertod) University of Ancona Dobele Horticultural Plant Breeding Experimental Station Universidad Michoacana de San Nicolás de Hidalgo (Uruapan) Norwegian Crop Research Institute, Planteforsk Njoes HortResearch, Inc., Motueka Research Institute of Pomology (Brzezna) Research Institute for Fruit Growing (Pitesti) VIR, St. Petersburg Fruit and Viticulture Research Centre (Cacak) IPTCH Vilamet (Cacak) Balsgard, Kristianstad Atatürk Central Horticultural Research Institute (Yalova) Driscoll’s Assoc. (E. Malling) East Malling Research (formerly Hort. Research Int.; Malling) Redeva Ltd. Scottish Crop Research Inst. (Dundee) Driscoll’s Assoc. (Watsonville) Plant Sciences Inc. (Watsonville) Florida A&M (Tallahassee) Univ. of Maryland, Virginia Tech Univ. of Wisconsin USDA-ARS, Beltsville N.C. State University USDA-ARS/Ore. St. Univ., Corvallis Wash. State Univ. (Puyallup) Northwest Plants Co. (Lynden) Driscoll’s Assoc. (Lynden) 9 Table 12.3. Red raspberry cultivars released since the 1970s. Location of releasing program Australia Bulgaria Canada British Columbia Manitoba Nova Scotia Ontario Québec Czech Republic Denmark Estonia Finland France Germany Hungary Mexico New Zealand The Netherlands Norway Poland Romania Russia Serbia (Cacak) Sweden Switzerland U.K. England Scotland U.S.A. California Minnesota NJ/Md/Virg/Wisc New York Oregon Washington Cultivar Alkoopina, Bogong, Dinkum, Glen Yarra Raliza, Samodiva, Ljlin, Essenna Poslata Chemainus, Chilliwack, Comox, Cowichan, Esquimalt, Kitsilano, Malahat, Qualicum, Saanich, Tulameen Double Delight, Red River, Souris Nova OAC Regal, OAC Regency Perron’s Red Granat Zenith Aita, Alvi, Helkal Jatsi, Jenkka, Ville Comtesse, Favorite, Galante, Meco, Princess, Wawi Rusilva (Rrabant), Resa (Lucana), Rubaca (Naniane), Weirula Fertodi aranyfurt, Fert. karmin (Marla), Fert. ketszertermo, Fert. rubina, Fert. Venus, Fert. Zamatos, Fert. Zenit Gina Clutha, Kaituna, Kiwigold, Motueka, Moutere Rakaia, Selwyn, Waiau, Waimea, Tadmor Marwe Balder, Borgund, Frosta, Hitra, Stiora, Tambar, Varnes, Vene Benefis, Beskid, Laska, Nawojka, Polana, Polka, Pokusa, Poranno Rosa Citria, Gustar, Opal, Ruvi, Star Approximately 35 floricane and 17 primocane cultivars; however information is not available in English leaving a great deal of uncertainty on timeframe of releases and accuracy of information (HK Hall, pers. comm.) Gradina, Krupna Dvorodna, Podgorina, Ariadne, Boheme, Carmen Elida, Framita, Himbo Star, Himbo Top (Rafzaqu) Autumn Bliss, Autumn Britten, Autumn Cascade, Autumn Cygnet, Autumn Byrd, Brice, Gaia, Joan Irene, Joan J., Joan Squire, Julia, Malling Augusta, Malling Hestia, Malling Joy, Malling Juno, Malling Minerva, Marcela, Octavia, Terri-Louise, Valentina Glen Ample, Glen Doll, Glen Garry, Glen Lyon, Glen Magna, Glen Moy, Glen Prosen, Glen Rosa, Glen Shee AnnaMaria, Bababerry, Driscoll Cardinal, D. Carmelina, D. Dulcita, D. Francesca, D. Madonna, D. Maravilla, Gloria, Godiva, Graton Gold, Hollins, Holyoke, Isabel, Joe Mello, Lawrence, PSI 79, PSI 114, PSI 127, PSI 168, PSI 737, PSI 744, PS 1070, PS 1764, PS-1703, Stonehurst, Sweetbriar, Tola, Wilhelm Nordic, Redwing Alice, Anne, Caroline, Claudia (Christmas Tree), Deborah, Emily, Esta (Esther), Georgia, Jaclyn, Josephine, Lauren Encore, Prelude, Ruby (Watson), Titan Amity, Chinook, Coho, Lewis, Summit Centennial, Cascade Bounty, Cascade Dawn, Cascade Delight, Cascade Nectar All Rubus breeding programs emphasize the development of cultivars with dependable yields of high quality fruit, suitability for shipping if for the fresh market and for machine 10 harvestability if for the processed market, adaptation to the local environment and improved pest and disease resistance. Resistance to Phytophthora fragariae C.J. Hickman var. rubi Wilcox & Duncan is a universal goal. European programs were very concerned with cane Botrytis (Botrytis cinerea Pers.: Fr.), spur blight (Didymella applanata [Niessl] Sacc.), and anthracnose (Elsinoë veneta [Burkolder] Jenk.). American programs are particularly concerned with resistance to Raspberry bushy dwarf virus (RBDV). While molecular genetics, including transgenic technologies, has been cautiously added to the Rubus breeders toolbox, there is currently no interest in the industry for transgenic cultivars, although a transgenic RBDV resistant 'Meeker' has been developed (Martin, pers. comm.). The programs that were using molecular tools were most commonly dealing with marker assisted selection, mapping, and genetic fingerprinting (see section on biotechnological approaches to genetic improvement). Modern raspberry breeders must be aware of industry changes so that they can effectively address these needs. Breeders must decide what kind of cultivars will be most appropriate for the increasing amount of tunnel production worldwide, the necessity of machine harvesting for processing, the demand for nutraceuticals by the consumer, and the fact that globalization means the product grown in one region can be shipped just about anywhere. Breeding programs must also recognize where their industries physically will be in the future. China, which has never had a significant commercial caneberry industry, is rapidly planting raspberries, and they will develop cultivars that are specifically adapted to their production regions (Wu et al. 2006). Regional cultivars will be needed that more efficiently produce high yields of high quality fruit in order to keep their industries competitive. Other changes facing all public breeding efforts are the rise in importance of private programs and the protection of intellectual property rights. Private companies with their own breeders and proprietary cultivars or public breeders with some part of their program privatized are no longer an anomaly and no longer regional. Patents, breeder's rights, and licenses, while not new, are becoming the standard (see chapter 14). While plant protection and the potentially associated royalty stream have reduced the level of germplasm exchange between programs, it has allowed for the stabilization or survival of breeding programs. 12.5 Genetics of important traits 12.5.1 Disease and pest resistance One of the primary factors associated with low yields, poor quality fruit, and degeneration of raspberry cultivars are viruses (Jennings 1988). The inheritance of virus resistance is often not known, however differences in susceptibility and resistance have often been noted among different species and genotypes (Jennings and Jones 1986, Jennings et al. 1991, Converse 1991, Jones and McGavin 1998). The pollen-born RBDV is the most serious raspberry virus disease worldwide in the commercial industry (Martin 2002) and it is common in the wild (Finn and Martin 1996, Chamberlain et al. 2003). While plant growth and fruit yield are often not affected by RBDV, on susceptible cultivars the fruit is crumbly making it worthless for the fresh market or for the higher value IQF processed market (Converse 1991). Rubus leucodermis, the western 11 North American counterpart to R. occidentalis, does not appear to carry RBDV in wild populations (Finn and Martin 1996) and will likely be a potential source of variability for breeding improved R. occidentalis genotypes (Finn et al. 2003). Rubus leucodermis was successfully incorporated into R. occidentalis germplasm to produce 'Earlysweet' (R. leucodermis is a grandparent) (Galletta et al. 1998c). While symptomless, Tobacco streak virus (TSV) is another common pollen borne virus. Virus-free planting stock is an important component of control; however, genetic resistance is the only long term viable control option (Converse 1991). Resistance to RBDV is based on a single dominant gene Bu (Jones et al. 1982, Knight and Barbara 1999). 'Willamette', an industry standard, as well as 'Chilcotin', 'Nootka', 'Haida' and 'Heritage' carry this gene (Daubeny 2002, Kempler et al. 2002). In addition, some genotypes such as 'Cowichan' have shown long term resistance and may carry this gene (Stahler et al. 1995, Kempler et al. 2005b). Despite this, it has been difficult to develop new commercial cultivars with this trait, and in fact, the low percentage of selections with immunity suggest that potentially a negative linkage exists between some traits important to commercial quality and disease resistance (P. Moore, pers. comm.). A strain of RBDV capable of infecting genotypes with the Bu gene has been found in Europe and Asia; resistance to this strain has been identified in some genotypes (Jennings et al. 1991). The aphid-born viruses that make up the raspberry mosaic complex [Rubus yellow net virus (RYNV), Black raspberry necrosis virus (BRNV), Raspberry leaf mottle virus (RLMV) and Raspberry leaf spot virus (RLSV)] continue to be major problems and can be devastating in red and black raspberries (Stace-Smith 1956, Halgren et al. 2007). In Europe, these viruses are vectored by Amphorophora idaei Börner and in North America by A. agathonica Hottes. While there is no immunity to the raspberry mosaic complex, the Ag1 resistance gene to the aphid vector has been successfully incorporated into many cultivars and programs continue to actively screen seedling populations for this resistance (Knight et al. 1960, Daubeny and Stary 1982). The use of A. idaei resistant cultivars in the U.K. has been effective for a long time; however, cultivars have been found to vary in their response to the aphid despite having the same source of resistance (Jones et al. 2000). The effectiveness of the gene for resistance seems to be compromised in plants grown with partial shade and there appear to be minor genes affecting susceptibility (Jones et al. 2000). Dossett (2007) found that populations from crosses among commercial black raspberry cultivars grown in the Pacific Northwest under substantial virus pressure generally had poorer vigor than did the populations derived from crosses between cultivars and a wild selection of R. occidentalis from North Carolina. This suggests that broadening the germplasm pool for disease tolerance and for other traits could be very important for genetic improvement (Weber 2003). Nematode borne viruses are commonly a problem with Tomato ringspot virus (TmSV) and Tobacco ringspot virus (ToSV) of primary concern in North America and Raspberry ringspot virus (RRSV), Tomato black ring virus (TBRV), Arabis mosaic virus and Strawberry latent ringspot virus (SLRV) of greatest concern in Europe. The primary vectors of these viruses are Xiphinema americanum Cobb. in North America and Longidorus elongates de Man and Xiphinema diversicaudatum Micoletsky in Europe. While sources of resistance to the nematode borne viruses, through resistance to the vector, have been identified in red raspberry and Rubus crataegifolius Bunge, they have not been pursued vigorously (Jennings 1964, Vrain and Daubeny 1986). 12 Table12.4. Genetics of pest and disease resistance in raspberry. Attribute Bacteria Crown gall Fungi Cane blight Cane Botrytis Cane spot Grey mold Late yellow rust Leaf spot Midge blight Phytophthora root rot Powdery mildew Raspberry yellow rust Spur blight Verticillium wilt Yellow rust Insects Amphorophora idaei Observations and source Willamette is resistant (Daubeny 1996) ‘Latham’ is resistant (Jennings et al. 1991); resistance is additive (Williamson and Jennings 1992) High levels of additive variation for resistance (Jennings 1983); the gene H controlling cane pubescence provides resistance (Williamson and Jennings 1992) Resistant genotypes identified (Jennings et al. 1991); major resistance genes may exist (Williamson and Jennings 1992) Resistant genotypes identified (Jennings 1988, Jennings et al. 1991) Resistant genotypes identified (Jennings et al. 1991) Good germplasm sources identified (Jennings et al. 1991) Resistant genotypes identified (Jennings et al. 1991) ‘Latham’, ‘Winkler’s Samling’, and ‘Cascade Bounty’ are resistant as are several species (Bristow 1988, Jennings et al. 1991, Moore and Finn 2007, Pattison and Weber 2005) Multiple resistance genes identified in red raspberry (Keep 1968b, Williamson and Jennings 1992) Major gene for resistance (Williamson and Jennings 1992) Resistant genotypes identified (Jennings et al. 1991); high levels of additive variation for resistance (Jennings 1988); the gene H controlling cane pubescence provides resistance (Williamson and Jennings 1992) Primarily additive resistance, ‘Willamette’ and ‘Southland’ tolerant (Fiola and Swartz 1994) Single gene for resistance (Anthony et al. 1986) Raspberry midge Raspberry beetle Raspberry budmoth Raspberry fruitworm Spider mite Multiple genes for resistance identified (Daubeny 1966, Daubeny and Stary 1982); resistant genotypes identified (Daubeny 1996) Resistant genotypes identified; multiple genes identified for various races (Knight et al. 1960, Knight et al. 1972) Cultivars with few splits in canes are resistant (Jennings et al. 1991) Primocane fruiting cultivars are resistant (Jennings et al. 1991) Resistant cultivars identified (Wilde et al. 1991) ‘Royalty’ purple raspberry has resistance (Shaefers et al. 1978) Resistant genotypes identified (Shanks and Moore 1996) Nematodes Pratylenchus penetrans Nootka is resistant (Vrain and Daubeny 1986) Aphis idaei Viruses Arabis mosaic Black raspberry necrosis Raspberry bushy dwarf Raspberry ringspot Raspberry leaf mottle Raspberry leaf spot Single gene for immunity (Jennings 1964); resistant genotypes identified (Jones and McGavin 1998) Most cultivars are tolerant (Jennings et al. 1991, Jones and McGavin 1998) Single gene for immunity (Jones et al. 1982); ‘Willamette’ is immune. Genotypes with long term resistance have been identified (Stahler et al. 1995, Kempler et al. 2005b); resistant cultivars identified for isolate RBDV-D200 but not RBDV-RB (Jones and McGavin 1998). Single gene for immunity (Jennings 1964); resistant cultivars identified (Jennings et al. 1991, Jones and McGavin 1998) All tested varieties susceptible (Jones and McGavin 1998) All tested varieties susceptible (Jones and McGavin 1998) 13 Table12.4. Continued. Attribute Raspberry yellow net Raspberry yellow spot Raspberry vein chlorosis Strawberry latent ringspot Tomato black ring Observations and source Most cultivars are tolerant (Jennings et al. 1991, Jones and McGavin 1998) No published source of resistance All tested varieties susceptible (Jones and McGavin 1998) Resistant genotypes identified (Jones and McGavin 1998) Single gene for immunity; resistant genotypes identified (Jennings et al. 1991, Jones and McGavin 1998) The most important cane diseases of raspberries in Europe are midge and cane blights. Midge blight is a disease complex instigated by damage from the raspberry midge, Resseliella theobaldi Barnes. Cane blight is caused by Leptosphaeria coniothyrium (Fuckel) Sacc., which generally enters through wounds caused by mechanical harvesting (Williamson and Jennings 1992). These two diseases are generally not important in North America. Several other fungal diseases cause significant damage. Grey mold, B. cinerea, is the most important fungal disease of raspberry fruit worldwide. Spur blight is a very important disease in the Pacific Northwest and eastern Europe, where it affects a large portion of the canes surface area, while in western Europe its effects are less severe, generally limited to individual buds. Problems with cane spot or anthracnose (E. veneta) are widespread. Leaf and cane spot (Sphaerulina rubi Demaree and Wilcox) often effect raspberries grown in warmer climates. Yellow rust [Phragmidium rubi-idaei (DC.) P. Karst] has variable, but sometimes severe effects across Europe and Australasia. Late yellow rust [Pucciniastrum americanum (Farl.) Arth.] can be severe in the eastern parts of North America. Sources of resistance have been found for many of these fungal diseases (Table 12.4). Gene H, for hairy vs. glabrous canes has been found to be associated with resistance to spur blight (Jennings 1983, Jennings 1988) and recently has been added to the raspberry linkage map (Graham et al. 2006). Keep et al. (1977a) found that R. coreanus imparted strong resistance to not only spur blight, but cane blight, anthracnose and the leaf disease powdery mildew [Sphaerotheca macularis (Fr.) Jaczewski]. Daubeny (1987) proposed that resistance to cane Botrytis was due to two gene pairs with the presence of at least two dominant genes necessary to give resistance. He also listed a number of resistant and susceptible cultivars. Sources of resistance to yellow rust have been identified by Anthony et al. (1986). Ramanathan et al. (1997) cloned two genes for polygalacturonase-inhibiting protein (PGIP1 and PGIP2) that could play a role in grey mold resistance. Plant PGIPs inhibit fungal endopolygalacturonases, which are released by fungi to degrade plant cell walls. Activity levels of PGIP were found to decline during floral and fruit development, but expression of PGIP was stable throughout development from closed flower to ripe fruit. Root rot (P. fragariae var. rubi) is a devastating problem throughout red raspberry production areas worldwide (Kennedy and Duncan 1993, Wilcox et al. 1993, Daubeny 2002). Fungicides, particularly metalaxyl, were effective at controlling the root rot organism from the 1980s-1990s and while it has not lost all effectiveness, breeding programs are being pressed to develop resistant cultivars. Some success has been accomplished with the release of resistant 'Cascade Bounty' and the tolerant 'Cascade Dawn' and 'Cascade Delight' (Moore 2004, Moore 2006, Moore and Finn 2007). Hydroponic culture methods have been developed that can classify phenotypes of individuals for their resistance to root rot (Pattison et al. 2004, Pattison and Weber 2005). The root disease Verticillium wilt (Verticillium albo-atrum 14 Reinke & Berthier and V. dahliae Kleb.) is also a common problem that is locally severe. While sources of resistance have been identified and the quantitative inheritance of tolerance documented (Fiola and Swartz 1989 and 1994), Verticillium wilt they have not been actively pursued by breeders. The bacterial disease crown gall, caused by Agrobacterium tumefaciens (E.F. Smith & Townsend) Conn, is common wherever caneberries are grown, and fireblight (E. amylovora [Burr.] Winslow et al.) and Pseudomonas blight (Pseudomonas syringae van Hall) can occasionally be a problem. While genetic resistance to fireblight has been identified (Stewart et al. 2005), no raspberry breeding program is actively breeding for resistance to bacterial diseases. Insect and mite problems are usually specific to regions or environments. In monocultures, insecticides/acaricides are often applied as needed for specific problems such as raspberry crown borer (Pennisetia marginata [Harris]), red-necked caneborer (Agrilus ruficollis [Fabricius]), strawberry bud weevil (Anthonomus signatus Say), brown and green stink bugs (Euschistus spp. and Acrosternum hilare Say, respectively), Japanese beetle (Popillia japonica Newman), thrips (eastern and western flower thrips, Frankliniella tritici Fitch and F. occidentalis Pergande, respectively), grass grub (Costelytra zealandica White), raspberry fruitworms (Byturus tomentosus Degeer in Europe and B. unicolor Say in North America), root weevils (Otiorhynchus singularis L., O. sulcatus Fab, O. ovatus L. and Sciopithes obscurus Horn), and foliar nematode (Aphelenchoides ritzemabosi [Schwartz] Steiner). Insecticides are also used as a “knockdown” to remove insects such as orange tortrix (Argyrotaenia citrana Fernald) that can be a contaminant in machine harvested fruit (Jennings 1988, Daubeny 1996, Clark et al. 2007, HK Hall pers. comm.). In New Zealand, caneberries are attacked severely by raspberry bud moth (Heterocrossa rubophaga Dugdale) and/or blackberry bud moth (Eutorna phaulacosma Meyrick) and the leaf roller species (Epiphyas postivittana Walker, Planotortrix exessana Walker, P. octo Dugdale, Ctenopseustis obliquana Walker, C. herana Felder, and Rogenhofer and Cnephasia jactatana Walker). Rubus occidentalis has been found to be a source of resistance to both groups and has been carried through four generations of breeding improvement into red raspberries (H.K. Hall, pers. comm.). As crops are moved to new regions or environments, nuisance or minor pests can become severe. Red raspberries grown in warm, dry environments are generally very susceptible to the two-spotted spider mite (Tetranychus urticae Koch), and therefore as glasshouse and tunnel production become more important parts of commercial production they are becoming more of a problem (Finn 2002). Resistance to this pest has been identified in red raspberry and related species (Shanks and Moore 1996). Numerous sources of disease and pest resistance have been identified in the wild raspberries (Table 12.4) and a good summary is presented by Jennings et al. (1991). Of particular note are a number of species within the Idaeobatus that carry multiple resistances including: 1) R. crataegifolius (fruit rot, cane Botrytis, cane midge, cane beetle and root lesion nematode), 2) R. coreanus (aphids, cane blight, spur blight, cane Botrytis, cane spot, cane beetle, powdery mildew, leaf spot and root rot), 3) R. mesogaeus Focke (cane Botrytis, cane blight and cane midge), 4) R. parvifolius (leaf spot, cane spot, spider mite and root rot, 5) R. occidentalis (aphids, bud moth, leaf rollers, cane beetle, two-spotted spider mite and fruit rot), and 6) R. pileatus Focke (cane blight, cane midge, cane Botrytis, spur blight, fruit rot and root rot). 15 12.5.2 Environmental adaptation Adaptation to low winter temperatures, high summer temperatures and low chilling are three of the most important characteristics sought by breeders for continued expansion of the raspberry industry. Lack of winter cold tolerance limits the range of successful raspberry cultivation in the continental climates of central and eastern Europe, and eastern and central North America (Warmund and George 1990, Daubeny 1996). The inheritance of winter hardiness is under complex genetic control. Winter hardy caneberries have four key characteristics: 1) rapid hardening in the fall before severe temperatures occur, 2) long rest or deep dormancy making them resistant to temperature fluctuations in the spring, 3) the ability to re-harden if initial cold tolerance is lost, and 4) late bud break (Warmund and George 1990, Daubeny 1996). It has been proven difficult to combine cold hardiness with early flowering and fruiting (Jennings 1988). Attempts have been made to predict relative hardiness in red raspberry using individual characteristics such as when leaf drop occurs, rates of bud development and bud water content, but hardiness has been most accurately assessed by evaluating reproductive performance in the field after “test” winters. Numerous raspberry cultivars with good winter hardiness have been identified in North America, Scandinavia, Eastern Europe, the former Soviet Union and the U.K. (Daubeny 1995 and 1996, Daubeny 1997 and 1999). Strong winter hardiness has also been described in native populations of the raspberries R. idaeus, R. sachalinensis H. Lev. (2n=4x=28), R. chamaemorus, R. crataegifolius, R. arcticus and R. arcticus subsp. stellatus (Table 12.1).The development of primocane fruiting raspberries probably had the most dramatic effect on the winter hardiness of any berry crop. Severe winter cold damage can be avoided in primocane fruiting raspberries by removing the canes after they are harvested in the fall and therefore, only those extremely cold winters that damage crowns are a problem. Raspberry production can be limited by fluctuating spring and fall temperatures, and low temperatures during fruiting. There is considerable variability among raspberry genotypes in their ability to set high proportions of their drupelets under cool conditions during flowering. In general, the raspberry cultivars developed in the U.K. are better adapted to cool temperatures than those developed in the Pacific Northwest, with some exceptions. The northwestern cultivar 'Meeker' has been shown to have good drupelet set in both locations (Dale and Daubeny 1985). Heat and drought are limiting in southern Europe, southeastern North America and much of the southern hemisphere. Since fruit quality standards are high in the commercial market, irrigation is becoming the standard practice and heat and ultraviolet (UV) damage are more of a concern than drought. Considerable variability has been found among raspberry cultivars for adaptation to high summer temperatures. The wild Asiatic raspberry species have been most widely used as sources of high temperature tolerance (Williams 1961, Stafne et al. 2000) and a low chilling requirement, although genes regulating a low chilling requirement have also been found in cool weather adapted R. idaeus (Rodriguez-A and Avita-G 1989). While breeders have attempted to use R. parvifolius as a source of heat tolerance and cultivars such as 'Dormanred', 'Southland' and 'Mandarin' have been produced that are purported to be either R. idaeus x R. parvifolius hybrids or second 2nd generation hybrids, this 16 route has never proven as successful/easy as it would appear to be in theory (Daubeny 1997, Stafne et al. 2000). In red raspberry, while there remains interest in low chilling cultivars, the use of long cane production techniques and primocane fruiting genotypes has largely circumvented this challenge. Long cane production is the practice where floricane fruiting cultivars are grown in northerly climates (e.g. Scotland), dug after they go dormant, refrigerated and then replanted with the entire cane intact in a warmer climate (e.g. Spain) where they quickly break bud and flower. For those breeders interested in reducing chilling requirement, the wild raspberry species R. biflorus Buch.-Ham. ex Sm., R. innominatus S. Moore, R. glaucus, R niveus and R. parvifolius are excellent sources of a low chilling requirement, while R. biflorus, R. coreanus, R. niveus, R. occidentalis, R. parvifolius and R. innominatus are sources of resistance to high temperatures. Much genetic variability exists for season extension among raspberry cultivars and species (Jennings et al. 1991). Fruiting season appears to be highly heritable trait, with some genotypes showing considerable environment interaction (Hoover et al. 1989). The fastest ripening cultivars have an early bloom date and a rapid developmental rate, although early flowering can be a problem in frosty areas. Among the wild raspberry species, R. corchorifolius L., R. crataegifolius, R. pungens Cambess. and R. spectabilis Pursh are generally early ripening, while R. innominatus, R. coreanus, and R. occidentalis are generally late. Rubus glaucus has an extended production season, while the season of R. flosculosus Focke is concentrated. 12.5.3 Plant characteristics Daubeny (1999) describes the ideal floricane raspberry cultivar as follows: “…has erect canes with few or no spines and adequate but not excessive cane numbers and cane heights. Fruiting laterals should be upright, strongly attached but flexible, and of moderate length with fruit well spaced.” He suggests the ideal primocane fruiting type “produces abundant canes that branch to produce higher numbers of fruiting nodes. Cane height is moderate, which in some environments will eliminate the need of supports.” All these characters are heritable and genetic variability exists for them among cultivars (Knight and Keep 1960, Keep et al. 1977b, Daubeny 1996), although no raspberry cultivar is perfect for all these traits. Breeding programs have used a variety of species to alter architectures when not available in cultivar quality material (Yeager 1950, Finn et al. 2002a and b). Ideally red raspberry cultivars are erect and sparsely-spined, with adequate but not excessive cane numbers and cane heights (Jennings et al. 1991). Spines are not generally a significant commercial issue for red raspberry as the spines are small and seldom noticed; however genes for spinelessness and its inheritance have been identified (Jennings 1984 and 1988, Jennings and Brydon 1990, Daubeny 1996). Most raspberry cultivars are not completely spine-free, but spineless ones do exist and many only have spines on the basal portions of canes making them spineless from a commercial production standpoint, whether hand or machine harvested. The s gene originally found by Lewis (1939) in segregates of 'Burnetholm' has been widely used in breeding. Black raspberry spines can be a commercial issue in that they are large and “aggressive”. However, since black raspberries are primarily mechanically pruned, machine harvested and 17 processed as puree or juice, where the product is pressed through a sieve, thornlessness has not been a high breeding priority. If the fresh black raspberry market is to be developed, thornlessness will become important and raspberry might be the most appropriate source of thornlessness, since no thornless black raspberries mutations have been identified. 12.5.4 Fruit quality The critical traits associated with high fruit quality in raspberry include size, shape, color, firmness, skin strength, texture, seed (botanically pyrene) size, flavor, and nutritional/nutraceutical content and ease of harvest. Obviously, whether the fruit is being grown for the fresh or processing market determines which traits rise or drop in importance (Figure 12.2). Machine harvested fruit are frozen or otherwise processed within hours of harvest and therefore do not need the same level of firmness that is essential for fruit for fresh shipping. Fruit that is processed needs high soluble solids, high titratable acidity levels, and relatively low pH in order that they have long shelf stability. Since fruit for processing is often only a small portion of a product, it is essential that they have intense flavor and color. A series of papers from Washington State University examined the relationships among raspberry fruit characteristics including firmness (Barritt 1982, Robbins and Sjulin 1989, Robbins and Moore 1990a, Robbins and Moore 1991). Barritt (1982) found very high heritability for fruit firmness in a diverse breeding population of raspberries containing genotypes from the Pacific Northwest and the United Kingdom. Daubeny (1996) attributes improvements in the firmness of modern cultivars to the incorporation of R. occidentalis through such cultivars as 'Glen Prosen' and 'Burnetholm', likely a selection from indigenous R. idaeus. Figure 12.1. Two different but acceptable ideals for red raspberry - Fruit on left has ideal color and acceptable fruit size for processing market; fruit on right is larger and "brighter" and is more appropriate for fresh market. Ease of harvest at maturity has been essential since the advent of viable commercial harvesters in the 1950s and 1960s for the processing industry and for the most efficient hand harvest for the fresh market (Hall et al. 2002). Important characteristics associated with machine harvesting are: 1) fruiting laterals that are flexible but firmly attached, 2) easy fruit 18 detachment, 3) concentrated ripening, and 4) firm fruit (Moore 1984). Since raspberries have the dynamic where each individual drupelet must form an abscission zone at their connection to the torus, there is a great range in ease of harvest from those genotypes whose berries fall at the slightest shake to those whose fruit dry on the torus and cannot be shaken off. While various tools have been used to try to objectively measure ease of harvest (Sjulin and Robbins 1987, Mason 1976), these methods have not proven practical enough to be adopted in breeding programs. Breeders most commonly estimate ease of harvest using subjective evaluation such as scoring how easily fruit can be removed by hand or noting how readily overripe fruit drop to the ground. When critical, breeding programs have incorporated commercial machines into their program. Most typically after a selection is made, it is put into machine harvest trials even before it is evaluated in an advanced replicated trial (Moore and Kempler pers. comm.). Some programs feel they can do an excellent job of evaluating seedlings for machine harvest by driving the machine over the seedling field (Sjulin, pers. comm.). The ease of harvest trait can be greatly affected by the environment (Daubeny 1996). In addition to the processing industry standards 'Meeker' and 'Willamette', all successful newer processing cultivars have this trait (e.g., 'Cascade Bounty', 'Chemainus', 'Chilliwack', 'Coho', 'Cowichan', and 'Saanich'). Appropriate fruit color is essential for the success of a new cultivar. Red raspberries for the fresh market must be bright and glossy red colored whereas those for processing need much greater color intensity (Sjulin and Robbins 1987, Robbins and Moore 1990b). Black raspberries, which are often sold for their natural colorant properties, need to be dark black. Blackberries and black raspberries, and to a lesser extent raspberries, naturally have a very intense color and high anthocyanin levels. Several major genes have been described that control fruit color in red raspberry including R for the rhamnose containing anthocyanins (Barritt and Torre 1975); T, which when recessive yellow fruit are produced (Crane et al. 1931); Bl, which is epistatic to T but which when dominant gives black or purple fruit (Britton et al. 1959); P, which is also epistatic to T but which give apricot/orange fruit color (Crane et al. 1931); Y in R. phoenicolasius and its counterpart which suppresses yellow color Ys; and Ycor, which has a similar effect in R. coreanus (Jennings and Carmichael 1980); however, there is some contention as to whether all these genes are valid (Keep 1984, Jennings 1988). The effects of processing and environment on the anthocyanin content of red raspberry juices made from various genotypes has been examined (Boyles and Wrolstad 1993, Rommel and Wrolstad 1993). In a breeding program, genotypes are objectively scored for color and then if they become potential processing cultivars their anthocyanin content is determined. As a compromise, Moore (1997a) found that the reflectance readings (a*/b*) from a tri-stimulus color meter correlated well (r = 0.73) with anthocyanin concentrations and required much less effort than anthocyanin extraction. A considerable amount of new research has been performed on variation patterns in the antioxidant capacity of Rubus species and crosses. The fact that anthocyanins and polyphenolics are powerful antioxidants has led a number of investigators to look at the nutraceutical/antioxidant levels of raspberries (Moyer et al. 2002, PerkinsVeazie and Kalt 2002, Wada and Ou 2002, Siriwoharn et al. 2004, Beekwilder et al. 2005, Anttonen and Karjalainen 2005, Moore et al. 2007, Weber et al. 2007). Conner et al. (2005a and b) estimated narrow-sense heritabilities for antioxidant capacity (AA), total phenolic content (TPH) and fruit weight from progeny of a factorial mating 19 design of seven female and six male red raspberry genotypes. A rapid response to selection appears possible, as heritability estimates were all high, at 0.54, 0.48 and 0.77 for AA, TPH and fruit weight, respectively. AA and TPH were only weakly correlated with fruit weight, suggesting that selection for high antioxidant capacity and large fruit weight is possible. In further work evaluating individual anthocyanin (ACY) content with total anthocyanin content and antioxidant capacity in the same families, Conner et al. found high values of h2 for individual ACYs (0.54 – 0.90), but ACY content and profile information were “inefficient proxies and predictors of AA in red raspberry fruit”. The inclusion of a pigment-deficient R. parvifolius x R. idaeus hybrid resulted in significant female and male contributions to variation, but its removal from the analysis made female x male interaction negligible. The overall conclusion from all of these studies is that the traits related to anthocyanin content and nutraceutical value are heritable and improvement should be expected with a recurrent mass selection breeding approach. The greater challenge for many of these traits is, when the human eye is not the best selection tool, are there tools that allow for these traits to be effectively, efficiently and cost effectively selected in seedling or parental populations? Dossett (2007) examined variation in fruit chemistry properties including pH, titratable acids, soluble solids, anthocyanin profiles, and total anthocyanins in 26 black raspberry families from a partial diallel cross among eight cultivars and a selection of R. occidentalis. For each of the traits general combining ability (GCA) effects were significant and larger than specific combining ability (SCA) effects. Narrow-sense heritability estimates were generally moderate to high when year effects were excluded from the analysis, indicating the potential for progress from selection within the examined families. Daubeny (1996) stated that when breeding caneberries, “Flavor, the most difficult of the quality traits to define, is becoming more important …”. While the statement that flavor is becoming more important is still accurate, our ability to define the trait and therefore successfully select for it is improving rapidly. The increased sophistication of flavor chemists instrumentation, combined with the sensory evaluation and the knowledge of the germplasm provided by a breeder is allowing a much greater understanding of the genetics of flavor and how to most efficiently select for it in seedling populations. Raspberry flavor has had considerable effort devoted to it over the years (Jennings 1988, Daubeny 1996) but recent research has looked at genetic, environmental, and treatment effects, such as freezing and thawing, on flavor (Morel et al. 1999, Casabianca and Graff 1994, Sewenig et al. 2005). One of the major challenges faced by breeders is to make selections based on fresh fruit quality in the field for a market where either the fruit are harvested immature and refrigerated for several days or frozen and later thawed for processed applications. The potential for the use of either molecular markers (Paterson et al. 1993) or some in-field tool that objectively, reliably and quickly determines flavor profiles are in the process of becoming a reality (Qian, pers. comm.). Overall post harvest fresh fruit quality, which is affected by treatment, and cultivar characteristics have been well studied and useful variability identified (Jennings 1988, Crandall and Daubeny 1990, Jennings 1991, PerkinsVeazie et al. 1996, Veazie et al. 1999 and 2000). Research is beginning to emerge on the genes associated with fruit ripening in Rubus. Jones et al. (2000) profiled changes in gene expression during raspberry fruit ripening and identified 34 up-regulated genes. Genes have been cloned from ripening fruit that are similar to major latex proteins and endo-polygalacturonases (Jones et al. 1998). L-phenylalanine- 20 lyase (PAL) and 4-Coumarate:CoA ligase (4CL), were found to be encoded by gene families in raspberry. Four classes of 4CL genes were identified that had distinct temporal patterns of expression during flower and fruit development (Kumar and Ellis 2003). PAL was found to be encoded by two similar genes in raspberry, RiPAL1 which was associated with early fruit ripening, and RiPAL2 which was more associated with later stages of development (Kumar and Ellis 2001). Twenty genes that play a rol in fruit ripening were identified by Jones et al. (1999) in the red raspberry 'Glen Clova'. Most of these genes were associated with cell wall hydrolysis and ethylene biosynthesis. Iannetta et al. (2000) cloned two putative endo-β-1,4 glucanase genes (RI-EGL1 and 2) from ripe receptacle mRNA. The expression of these genes were limited to ripe-fruit receptacles, and the application of 1-methylcyclopropene (1-MCP) to green fruit indicated that ethylene accelerates raspberry abscission and increases EGase activity. 12.5.5 Yield Yield in raspberries is a complex trait that is quantitatively inherited and is the sum of many components (Dale 1989, Hoover et al. 1986, Daubeny 1996, Pritts 2002). Yield in floricane fruiting types is dependent on the factors influencing the growth and development of canes in the first and second year. The most critical parameters in the first year are cane number, height and diameter, the number of nodes and root growth. In the second year, fruiting laterals per cane and fruit numbers per lateral are especially important to yield, along with fruit weight (composed of ovule number, drupelet set and drupelet size). The highest yielding plants have abundant numbers of intermediate sized canes, dense node numbers in the cropping area and vigorous root growth. Dense node numbers can be produced by a compact growth habit or short internodes. High yields have been obtained by selecting for fruit size, lateral numbers and fruits per lateral, although excesses in any of the yield components can lead to negative component interactions (Jennings 1980, Dale and Daubeny 1985). In red raspberry breeding plots, a single year’s data is fairly predictive of fruit size and firmness but not incidence of Botrytis fruit rot or yield (Moore 1997b). All the yield components are inherited additively in raspberries with significant genetic interactions (Daubeny 1996). While single genes have been identified that influence fruit size - L1 which enhances fruit size, and l2 which results in “miniature” fruit (Jennings 1961, Jennings 1966a and b), the L1 gene has proven to be very unstable and most breeding programs have actively worked to eliminate it from their programs. Among the wild species, R. cockburnianus Hemsl., R. flosculosus and R. innominatus have high fruit numbers per lateral; large fruit size is found in R. glaucus, R. lasiostylus Focke, and R. nubigenus (=R. macrocarpus) (Knight et al. 1989, Finn et al. 2002a and b). Yield in primocane fruiting raspberries is most dependent on cane number and amount of branching, which directly influence the number of fruiting laterals (Hoover et al. 1988). Fruit size is negatively associated with high cane numbers in some raspberry cultivars, but not all. Earliness can also be an important component of yield in primocane fruiting types, particularly where the growth season is short. Considerable genetic variability exists for fruiting season among primocane raspberry cultivars, and several wild species have been used to breed early primocane fruiting types including R. arcticus, R. odoratus L. and R. spectabilis (Howard 1976, Keep 1988). 21 12.6 Crossing and evaluation techniques The crossing and evaluation of raspberries is very similar to that of blackberries, which is thoroughly outlined in Chapter 3. Raspberries are self compatible and in many cases, interspecific crosses are possible, even across ploidies (see section on germplasm resources). Raspberry flowers are typical for the Rosaceae and their emasculation and pollination techniques are similar to those for others in the family. Rubus seeds generally require scarification and stratification. The standard germination-to-field protocol consists of an acid scarification (concentrated sulfuric acid), water and sodium bicarbonate rinse, a 5 – 6 days calcium hypochlorite soak, another rinse, overnight warm stratification, 6 – 10 weeks cold stratification, 1 – 4 weeks germination and transplanting, six weeks as greenhouse plugs, one week acclimation to outdoor conditions and, finally, field planting. While most seed lots are germinated using this basic procedure, in vitro procedures are used for small seed lots or for seeds from wide or challenging crosses. The in vitro germination protocol involves surface sterilization with ethanol and bleach, a 6 – 10 weeks cold stratification, repeat surface sterilization, dissection, 1 – 2 weeks germination on media, transplanting, six weeks as greenhouse plugs and one week of acclimation prior to field planting. For field testing, a minimum of 100 seedlings per cross are typically planted with each plant at 0.8 – 0.9 m apart within the row. The primocanes produced in the second year are intensively managed so that all of the seedlings can be evaluated in the third year, two years after planting. Primocane fruiting seedlings can be evaluated in the planting year in many climates but are often left for a second year to ensure that the assessment of the flowering and fruiting habit is accurate and not affected by any juvenility. In northern and southern California, the evaluation of primocane fruiting seedlings would roughly parallel the production systems. For northern California, seedlings are winter planted; the primary evaluation is done in the fall, followed by a second spring evaluation. For southern California, the seedlings are started and grown to 10 – 20 cm tall, chilled, summer planted and evaluated just once, the following winter. Only 0.5 – 1% of the seedlings are selected, primarily based on the perceived vigor, yield and fruit quality with few notes or detailed evaluations made. The most elite selections are propagated for more trialing, in either single, multiple plant observation plots or in replicated trials. Decisions about release as a cultivar are generally made 8 – 12 years after the initial crosses. 12.7 Biotechnological approaches to genetic improvement 12.7.1 Genetic mapping, QTL analysis and genomic resources A wide array of molecular markers has been developed in Rubus (Antonius-Klemola 1999, Hokanson 2001, Stafne 2005). Genomic in situ hybridization (GISH) and fluorescence in situ hybridization (FISH) have been utilized to distinguish between raspberry and blackberry chromosomes, and identify translocations (Lim et al. 1998). Weber et al. (2003) used RFLP markers to assess genetic diversity in black raspberry and found that on the whole the group of genotypes they evaluated had a collective marker similarity of 92% compared to 70% reported for red raspberry (Graham et al. 1994). 22 Graham et al. (2004) constructed a genetic linkage map of red raspberry ('Glen Moy' x 'Latham') using AFLP, genomic-SSR and EST-SSR markers. The SSR markers were developed from genomic and cDNA libraries of 'Glen Moy'. A total of 273 markers were mapped in nine linkage groups, covering 789 cM (Figure 12.3). This map was used to search for QTL associated with cane spininess, root sucker density and root sucker spread. Two QTL for cane spininess were mapped to linkage group 2, while one QTL for root sucker density and two for root sucker spread were mapped to linkage group 8. Most of these QTL explained in excess of 50% of the phenotypic variability. Graham et al. (2006) have most recently added gene H to their linkage map, which determines whether canes are pubescent (HH or Hh) or glabrous (hh). H has been found to be closely associated with cane botrytis and spur blight resistance, but not to cane spot or rust. 12.7.2 Regeneration and transformation Regeneration and transformation systems have been developed for raspberries utilizing leaves, cotyledons and internodal stem segments (Swartz and Stover 1996, Kokko and Kärenlampi 1998). A number of factors have been shown to play critical roles in determining regeneration and transformation rates including environmental conditions (Meng et al. 2004, Palonen and Buszard 1998), leaf orientation (McNicol and Graham 1990), type of hormone (Fiola et al. 1990, Millan-Mendoza and Graham 1999), and most importantly genotype (Reed 1990, Owens et al. 1992, Graham et al. 1997). Mathews et al. (1995) transformed 'Canby', 'Chilliwack' and 'Meeker' red raspberries with the gene for S-adenosylmethionine (SAMase), as a potential strategy to delay fruit decay. Leaf and petiole explants were inoculated with Agrobacterium strain EHA 105 carrying the binary vectors pAG1452 or pAG1552 encoding SAMase under control of the wound and fruit specific E4 promoter. Petiole explants produced the highest rates of transformation, and more transformants were recovered using hygromycin phospotransferase (HPT) as the selective agent rather than neomycin phospotransferase (NPT11). They reported on establishment of the transformants in soil, but have not published information on levels of resistance to decay. There have been two attempts to generate resistance to raspberry bushy dwarf (RBDV) using Agrobacterium–mediated transformation. Jones et al. (1998) isolated the coat protein gene (cp) from a resistance-breaking strain of RBDV and transformed plants with it in the sense and anti-sense orientation. Some of their transformants were partially resistant. Taylor and Martin (1999) sequenced the cp gene, mutations of the movement protein and nontranslatable RNA of RBDV and transformed 'Meeker' red raspberry with each of these constructs (Martin et al. 2001). Transformed 'Meeker' from this work, has been successfully field trialed and the processed fruit quality compared to wild-type 'Meeker' with no discernable differences, although it is not commercially grown (Martin and Qian, pers. comm.). 'Ruby' was successfully transformed with the DEfH9-iaaM gene which produces parthenocarpic fruit (Mezzetti et al. 2002). 23 Figure 12.3. The genetic linkage group of red raspberry built with AFLP, genomic-SSR markers and EST-SSR markers. OTL regions for spines, root sucker spread and root sucker density are also noted (Graham et al. 2004). 24 12.8 References Anthony VM, Williamson B, Jennings DL, Shattock RC (1986) Inheritance of resistance to yellow rust (Phragmidium rubi-idaei) in red raspberry. Ann Appl Biol 109:365-374 Antonius-Klemola K (1999) Molecular markers in Rubus (Rosaceae) research and breeding. J Hort Sci Biotech 74:149-160 Anttonen MJ, Karjalainen RO (2005) Environmental and genetic variation of phenolic compounds in red raspberry. J Food Comp Anal 18:759-769 Ballington JR, Moore JN (1995) NC 194 primocane-fruiting thorny erect tetraploid blackberry germplasm. Fruit Var J 49:101-102 Barritt BH (1982) Heritability and parent selection for fruit firmness in red raspberry. HortScience 17:648-649 Barritt BH, Torre LC (1975) Inheritance of fruit anthocyanins pigments in red raspberry. HortScience 10:526528 Beekwilder J, Hall R, de Vos CHR (2005) Identification and dietary relevance of antioxidants from raspberry. Biofactors 23:197-205 Bell NC, Strik BC, Martin LW (1995a) Effect of primocane suppression date on 'Marion' trailing blackberry. I. Yield components. J Am Soc Hort Sci 120:21-24 Boyles MJ, Wrolstad RE (1993) Anthocyanin composition or red raspberry juice: influences of cultivar, processing, and environmental factors. J Food Sci 58:1135-1141 Britton DM, Lawrence FJ, Haut IC (1959) The inheritance of apricot fruit color in raspberries. Can J Genet Cytol 1:89-93 Bristow PR, Daubeny HA, Sjulin TM, Pepin HS, Nestby R, Windom GE (1988) Evaluation of Rubus germplasm for reaction to root rot caused by Phytophthora erythroseptica. J Amer Soc Hort Sci 113:588-591 Casabianca H, Graff JB (1994) Enantiomeric and isotopic analysis of flavour compounds of some raspberry cultivars. J Chromatogr A 684:360-365 Chamberlain CJ, Kraus J, Kohnen PD, Finn CE, Martin RR (2003) First report of Raspberry bushy dwarf virus in Rubus multibracteatus from China. Plant Disease 87:603 Clark JR, Moore JN, Lopez-Medina J, Perkins-Veazie P, Finn CE (2005) Prime-Jan (APF-8) and Prime-Jim (APF-12) primocane-fruiting blackberries. HortScience 40:852-855 Conner AM, McGhie TK, Stephens MJ, Hall HK, Alspach PA (2005a) Variation and heritability estimates of anthocyanins and their relationship to antioxidant activity in a red raspberry factorial design. J Am Soc Hort Sci 130:534-542 Conner AM, Stephens MJ, Hall HK, Alspach PA (2005b) Variation and heritabilities of antioxidant activity and total phenolic content estimated from a red raspberry factorial experiment. J Am Soc Hort Sci 130:403411 Converse RH (1991) Diseases caused by viruses and viruslike agents. p. 42-58. In: Ellis MA, Converse RH, Williams RN, Williamson B (eds.) Compendium of raspberry and blackberry diseases and insects. APS Press, St. Paul, Minn Cortell JM, Strik BC (1997) Effect of floricane number in 'Marion' trailing blackberry. II. Yield components and dry mass partitioning. J Am Soc Hort Sci 122:611-615 Crandall PC, Daubeny HA (1990) Raspberry management. p. 157-213 In: Galletta GJ, Himelrick DG (eds.) Small fruit crop management. Prentice Hall, Englewood Cliffs NJ Crane MB, Lawrence WJC (1931) Inheritance of sex, colour and hairiness in the raspberry, Rubus idaeus L. J Gen 2:243-255 Dale A (1989) Productivity in red raspberries. Hort Rev 11:185-228 Dale A, Daubeny HA (1985) Genotype-environmental interactions involving British and Pacific Northwest raspberry cultivars. HortScience 20:68-69 Dale A, McNicol RJ, Moore PP, Sjulin TM (1989) Pedigree analysis of red raspberry. Acta Hort 262:35-39 Dale A, Moore PP, McNicol RJ, Sjulin TM, Burmistrov LA (1993) Genetic diversity of red raspberry varieties throughout the world. J Amer Soc Hort Sci 118:119-129 Darrow GM (1920) Are our raspberries derived from American or European species? J Hered 11:179-184 Daubeny HA (1983) Expansion of genetic resources available to red raspberry breeding programs. Proc 21st Int Hort Cong 1:150-155 Daubeny HA (1987) A hypotheses for inheritance of resistance to cane Botrytis in red raspberry. HortScience 22:116-119 Daubeny HA (1995) In: Cummins JN (ed.) Register of new fruit and nut varieties Brooks and Olmo list no. 37: 25 Blackberries and hybrid berries. HortScience 30:1136-1137 Daubeny HA (1996) Brambles. In: Janick J, Moore JN (eds.) Fruit Breeding. Vol. II. Vine and small fruits. John Wiley & Sons, NY Daubeny HA (1997) Raspberry. p. 635-662, The Brooks and Olmo register of fruit and nut varieties. Third ed. ASHS Press, Alexandria, Va Daubeny HA (1999) Raspberry. In: Okie WR (ed.) Register of new fruit and nut varieties List 39. HortScience 34:196-197 Daubeny HA (2002) Raspberry. In: Okie WR (ed.) Register of new fruit and nut varieties List 41. HortScience 37:264-266 Daubeny H (2002) Raspberry breeding in the 21st century. Acta Hort 585:69-72 Daubeny HA, Stary D (1982) Identification of resistance to Amphorophora agathonica in the native North American red raspberry. J Am Soc Hort Sci 91:593-597 Dossett M (2007) Variation and heritability of vegetative, reproductive and fruit chemistry traits in black raspberry (Rubus occidentalis L.) M.S. Thesis, Oregon State University, Corvallis, Ore Drain BD (1952) Some inheritance data with black raspberries. Proc Amer Soc Hort Sci 60:231-234 Drain BD (1956) Inheritance in black raspberry species. Proc Amer Soc Hort Sci 68:169-170 Drake CA, Clark JR (2003) Effects of pruning and cropping on field-grown primocane-fruiting blackberries. HortScience 38:260-262 Finn CE (1999) Temperate berry crops. pp 324-333 In: Janick J (ed.) Perspectives on new crops and new uses. ASHS Press, Alexandria, Virg Finn CE (2006) Caneberry breeders in North America. HortScience 41:22-24 Finn CE, Knight VH (2002) What's going on in the world of Rubus breeding? Acta Hort 585:31-38 Finn CE, Lawrence FJ, Strik BC, Yorgey B, DeFrancesco J (1999a) ‘Siskiyou’ trailing blackberry. HortScience 34:1288-1290 Finn CE, Lawrence FJ, Yorgey B, Strik BC (2001) 'Coho' red raspberry. HortScience 36:1159-1161 Finn CE, Martin RR (1996) Distribution of tobacco streak, tomato ringspot, and raspberry bushy dwarf viruses in Rubus ursinus and R. leucodermis collected from the Pacific Northwest. Plant Dis 80:769-772 Finn CE, Moore PP, Kempler C (2007) Raspberry cultivars: What’s new? What’s succeeding? Where are breeding programs headed? Acta Hort (In press) Finn CE, Swartz HJ, Moore PP, Ballington JR, Kempler C (2002a) Use of 58 Rubus species in five North American breeding programs-breeders notes. Acta Hort 585:113-119 Finn CE, Swartz HJ, Moore PP, Ballington JR, Kempler C (2002b) Breeders experience with Rubus species. http://www.ars-grin.gov/cor/rubus/rubus.uses.html Finn CE, Wennstrom K, Link J, Ridout J (2003) Evaluation of Rubus leucodermis populations from the Pacific Northwest. HortScience 38:1169-1172 Fiola JA, Hassan MA, Swartz HJ, Bors RH, McNichols R (1990) Effect of thidiazuron, light fluence rates, and kanamycin on in vitro shoot organogenesis from excised Rubus cotyledons and leaves. Plant Cell Tissue and Organ Culture 20:223-228 Fiola JA, Swartz HJ (1989) Screening raspberry (Idaeobatus) hybrids for resistance to Verticillium albo-atrum. Acta Hort 262:181-187 Fiola JA, Swartz HJ (1994) Inheritance of tolerance to Verticillium albo-atrum in raspberry. HortScience 29:1071-1073 Galletta GJ, Maas JL, Enns JM (1998) 'Earlysweet' black raspberry. Fruit Var J 52:123 Graham J, Iasi L, Millam S (1997) Genotype-specific regeneration from a number of Rubus cultivars. Plant Cell Tissue and Organ Culture 48:167-173 Graham J, McNichols R, Greig K, Van de Ven WTG (1994) Identification of red raspberry cultivars and an assessment of their relatedness using fingerprints produced by random primers. J Hort Sci 69:123-130 Graham J, Smith K, MacKenzie K, Jorgenson L, Hackett C, Powell W (2004) The construction of a genetic linkage map of red raspberry (Rubus idaeus subsp. idaeus) based on AFLPs, genomic-SSR and ESTSSR markers. Theor Appl Genet 109:740-749 Graham J, Smith K, Tierney I, MacKenzie K, Hackett C (2006) Mapping gene H controlling cane pubescence in raspberry and its association with resistance to cane botrytis and spur blight, rust and cane spot. Theor Appl Genet 112:818-831 Halgren A, Tzanetakis IE, Martin RR (2007) Identification, characterization and detection of Black raspberry necrosis virus. Phytopathology 97:44-50 Hall HK, Stephens MJ, Alspach P, Stanley CJ (2002a) Traits of importance for machine harvest of raspberries. Acta Hort 585:607-610 Hedrick UP (1925) The small fruits of New York. J.B. Lyon. Albany, NY 26 Hellman EW, Skirvin RM, Otterbacher AG (1982) Unilateral incompatibility between red and black raspberries. J Am Soc Hort Sci 107:718-784 Hokanson SC (2001) SNiPs, chips, BACs, and YACs: are small fruits part of the party mix. HortScience 36:859-871 Hoover E, Luby J, Bedford D (1986) Yield components of primocane-fruiting red raspberries. Acta Hort 183:163-166 Hoover E, Luby J, Bedford D, Pritts M (1988) Vegetative and reproductive yield components of primocanefruiting red raspberries. J Am Soc Hort Sci 113:824-826 Howard GS (1976) 'Pathfinder' and 'Trailblazer' everbearing raspberries released. Fruit Var J 30:94 Iannetta PPM, Wyman M, Neelam A, Jones C, Taylor MA, Davies HV, Sexton R (2000) A causal role for ethylene and endo-β-1,4-glucanase in the abscission of red-raspberry (Rubus idaeus) druplets. Physiol Plantarum 110: 535-543 Jennings DL (1961) Mutation for larger fruit in the raspberry. Nature 191:302-303 Jennings DL (1964) Studies on the inheritance in the red raspberry of immunities from three nematode-borne viruses. Genetica 34:152-164 Jennings DL (1966a) The manifold effects of genes effecting fruit size and vegetative growth in the raspberry, I. gene L1. New Phytol 65:176-187 Jennings DL (1966b) The manifold effects of genes effecting fruit size and vegetative growth in the raspberry, II. gene l2. New Phytol 65:188-191 Jennings DL (1980) Recent progress in breeding raspberries and other Rubus fruits at the Scottish Horticulture Research Institute. Acta Hort 112:109-116 Jennings DL (1983) Inheritance of resistance to Botrytis cinerea and Didymella applanata in canes of Rubus idaeus, and relationships between these resistances. Euphytica 32:895-901 Jennings DL (1984) A dominant gene for spinelessness in Rubus, and its use in breeding. Crop Res 24:45-50 Jennings DL (1988) Raspberries and blackberries: their breeding, diseases and growth. Academic Press, London Jennings DL, Brydon E (1990) Variable inheritance of spinelessness in progenies of a mutant of the red raspberry cv. Willamette. Euphytica 46:71-77 Jennings DL, Carmichael E (1980) Anthocyanin variation in the genus Rubus. New Phytol 84:505-513 Jennings DL, Daubeny HA, Moore JM (1991) Blackberries and raspberries (Rubus). pp 329-320 In: Moore JN, Ballington JR (eds.) Genetic resources of fruit and nut crops, vol 1. International Society for Horticultural Science, Wageningen Jennings DL, Jones AT (1986) Immunity from raspberry vein chlorosis virus in raspberry and its potential for control of the virus through plant breeding. Ann Appl Biol 108:417-422 Jones AT, McGavin WJ (1998) Infectibility and sensitivity of U.K. raspberry, blackberry and hybrid berry cultivars to Rubus viruses. Ann Appl Biol 132:239-251 Jones AT, McGavin WJ, Birch ANE (2000) Effectiveness of resistance genes to the large raspberry aphid, Amphorophora idaei Börner, in different raspberry (Rubus idaeus L.) genotypes and under different environmental conditions. Ann Appl Biol 136:107-113 Jones AT, Murant AF, Jennings DL, Wood GA (1982) Association of raspberry bushy dwarf virus with raspberry yellows disease: Reaction of Rubus species and cultivars, and the inheritance of resistance. Ann Appl Biol 100:135-147 Jones CS, Davies HV, McNicol RJ, Taylor MA (1998) Cloning of three genes up-regulated in ripening raspberry fruit (Rubus idaeus cv. Glen Clova). J Plant Physiol 153:643-648 Jones CS, Davies HV, Taylor MA (2000) Profiling of changes in gene expression during raspberry (Rubus idaeus) fruit ripening by application of RNA fingerprinting techniques. Planta 211:708-714 Keep E (1984) Inheritance of fruit color in a wild Russian red raspberry seedling. Euphytica 33:507-515 Keep E (1988) Primocane (autumn)-fruiting raspberries: A review with particular reference to progress in breeding. J Hort Sci 63:1-18 Keep E, Knight RL (1968) Use of the black raspberry (Rubus occidentalis L) and other Rubus species in breeding red raspberries. Rep E Malling Res Stn for 1967 p. 105-107 Keep E, Knight VH, Parker JH (1977a) The inheritance of flower color and vegetative characters in Rubus coreanus. Euphytica 26:185-192 Keep E, Knight VH, Parker JH (1977b) Rubus coreanus as donor or resistance to cane disease and mildew in red in red raspberry breeding. Euphytica 26:505-510 Kempler C, Daubeny HA, Frey L, Walters T (2006) ‘Chemainus’ red raspberry. HortScience 41:1364-1366 Kempler C, Daubeny H, Harding B (2002) Recent progress in breeding red raspberries in British Columbia, Canada. Acta Hort 585:47-50 27 Kempler C, Daubeny HA, Harding B, Baumann T, Finn CE, Moore PP, Sweeney M, Walters T (2007) ‘Saanich’ red raspberry. HortScience 42 (In press) Kempler C, Daubeny HA, Harding B, Finn CE (2005a) ‘Esquimalt’ red raspberry. HortScience 40:2192-2194 Kempler C, Daubeny HA, Harding B, Kowalenko CG (2005b) ‘Cowichan’ red raspberry. HortScience 40:19161918 Kennedy DM, Duncan JM (1993) Occurrence of races of Phytophthora fragariae var Rubi on raspberry. Acta Hort 352:555-559 Knight VH (1993) Review of Rubus species used in raspberry breeding at East Malling. Acta Hort 352:363-371 Knight VH, Barbara BJ (1999) A review of raspberry bushy dwarf virus at HRI-East Malling and the situation in a sample of commercial holdings in England in 1995 and 1996. Acta Hort 505:263-271 Knight VH, Briggs JB, Keep E (1960) Genetics of resistance to Amphorophora rubi (Kalt.) in the raspberry, II: the genes A2-A7 from the American variety, Chief. Genet Res 1:319-331 Knight VH, Jennings DL, McNicol RJ (1989) Progress in the UK raspberry breeding programme. Acta Hort 262:93-103 Knight VH, Keep E (1960) The genetics of suckering and tip rooting in the raspberry. In: Rep E Malling Res Station 1959, p. 57-62 Kokko HI, Karenlampi SO (1998) Transformation of arctic bramble (Rubus arcticus L.) by Agrobacterium tumefaciens. Plant Cell Reports 17:822-826 Kumar A, Ellis BE (2001) The phenylalanine ammonia-lyase gene family in raspberry. Structure, expression and evolution. Plant Physiol 127:230-239 Kumar A, Ellis BE (2003) 4-Coumarate:CoA ligase gene family in Rubus idaeus: cDNA structures, evolution and expression. Plt Mol Bio 51:327-340 Lewis D (1939) Genetical studies in cultivated raspberries. I. Inheritance and linkage. J Genet 38:367-379 Lim KY, Leitch IJ, Leitch AR (1998) Genomic characterization and the detection of raspberry chromatin in polyploid Rubus. Theo Appl Gene 97:1027-1033 Lopez-Medina J, Moore JN (1999) Chilling enhances cane elongation and flowering in primocane-fruiting blackberries. HortScience 34:638-640 Lopez-Medina J, Moore JN, McNew RW (2000) A proposed model for inheritance of primocane fruiting in tetraploid erect blackberry. J Am Soc Hort Sci 125:217-221 Mathews H, Wagoner W, Cohen C, Kellogg J, Bestwick R (1995) Efficient genetic transformation of red raspberry, Rubus idaeus L. Plant Cell Rpt 14:471-476 McPheeters KD, Skirvin RM (1983) Histogenic layer manipulation in chimeral ‘Thornless Evergreen’ trailing blackberry. Euphytica 32:351-360 Martin RR, Mathews H (2001) Engineering resistance to raspberry bushy dwarf virus. Acta Hort 551:33-38 Martin RR (2002) Virus diseases of Rubus and strategies for their control. Acta Hort 585:265-270 Mason DT (1976) Changes in the fruit retention strength of the red raspberry (Rubus idaeus L.) during ripening and their relevance to the selection of raspberry clones suitable for mechanical harvesting. Acta Hort 60:113-122 McNicol RJ, Graham J (1990) In vitro regeneration of Rubus from leaf and stem segments. Plant Cell Tissue and Organ Culture 21:45-50 Mezzetti B, Landi L, Spena A (2002) Biotechnology for improving Rubus production and quality. Acta Hort 585:73-78 Millan-Mendoza B, Graham J (1999) Organogenesis and micropropagation in red raspberry using florchlorfenuron (CPPU). J Hortic Sci Biotech 74:219-223 Moore PP (1993) Variation in drupelet number and drupelet weight among raspberry clones in Washington. Acta Hort 352:405-412 Moore PP (1997a) Estimation of anthocyanin concentration from color meter measurements of red raspberry fruit. HortScience 32:135 Moore PP (1997b) Year-to-year consistency of harvest data in raspberry breeding plots. J Amer Soc Hort Sci 122:211-214 Moore PP (1998) Variation in drupelet number and weight in Pacific Northwest red raspberries. Fruit Var J 52:103-106 Moore PP (2004) ‘Cascade Delight’ red raspberry. HortScience 39:185-187 Moore PP (2006) ‘Cascade Dawn’ red raspberry. HortScience 41:857-859 Moore PP, Finn CE (2007) ‘Cascade Bounty’ red raspberry. HortScience 42:393-396 Moore PP, Perkins-Veazie P, Weber CA, Howard L (2007) Environmental effect on antioxidant content on ten raspberry cultivars. Acta Hort (In press) Moyer R, Hummer K, Finn C, Frei B, Wrolstad R (2002) Anthocyanins, phenolics and antioxidant capacity in 28 diverse small fruits: Vaccinium, Rubus and Ribes. J Agric Food Chem 50:519-525 Morel S, Harrison RE, Muir DD, Hunter EA (1999) Genotype, location and harvest date effects on the sensory character of fresh and frozen red raspberries. J Amer Soc Hort Sci 124:19-23 Ourecky DK (1975) Brambles. pp 98-129 In: Janick J, Moore JN (eds.) Advances in Fruit Breeding. Purdue Univ. Press, West Lafayette, Indiana Ourecky DK, Slate GL (1966) Hybrid vigor in Rubus occidentalis-R. leucodermis seedlings. In: Proc 17th Int Hort Cong 1: Abstr 277 Owens Y, de Novoa C, Conner AJ (1992) Comparison of in vitro shoot regeneration protocols from Rubus leaf explants. New Zealand J Crops and Hort Sci 20:471-476 Oydvin J (1970) Important breeding lines and cultivars in raspberry breeding. St Forsokag Njos 1970:1-42 Palonen P, Buszard D (1998) In vitro screening for cold hardiness of raspberry cultivars. Plant Cell Tissue and Organ Culture 53:213-216 Paterson A, Piggott JR, Jiang J (1993) Approaches to mapping loci that influence flavor quality in raspberries. In: Spanier AM, Okai H, Tamura M (eds.) Food Flavor and Safety. ACS Symposium Series 528:110115 Pattison JA, Weber CA (2005) Evaluation of red raspberry cultivars for resistance to Phytophthora rot root. J Amer Pom Soc 59:50-56 Pattison JA, Wilcox WF, Weber CA (2004) Assessing the resistance of red raspberry (Rubus idaeus L.) genotypes to Phytophthora fragariae var. rubi in Hydroponic culture. HortScience 39:1553-1556 Perkins-Veazie P, Collins JK, Clark JR (1996) Cultivar and maturity affect postharvest quality of fruit from erect blackberries. HortScience 31:258-261 Perkins-Veazie P, Collins JK, Clark JR (1999) Cultivar and storage temperature effects on the shelflife of blackberry fruit. Fruit Var J 53:201-208 Perkins-Veazie P, Collins JK, Clark JR (2000a) Shelflife and quality of 'Navaho' and 'Shawnee' blackberry fruit stored under retail storage conditions. J Food Quality 22:535-544 Perkins-Veazie P, Kalt W (2002) Postharvest storage of blackberry fruit does not increase antioxidant levels. Acta Hort 585:521-524 Pritts MP (2002) From plant to plate: How can we redesign Rubus production systems to meet future expectations. Acta Hort 585:537-543 Ramanathan V, Simpson CG, Thow G, Iannetta PPM, McNicol RJ, Williamson B (1997) cDNA cloning and expression of polygalacturonase-inhibiting proteins (PGIPs) from red raspberry (Rubus idaeus). J Exp Bot 48:1185-1193 Reed BM (1990) Multiplication of Rubus germplasm in vitro: a screen of 256 accessions. Frt Var J 44:141-148 Robbins J, Moore PP (1990a) Relationship of fruit morphology and weight to fruit strength in ‘Meeker’ red raspberry. HortScience 25:679-681 Robbins JA, Moore PP (1990b) Color change in fresh red raspberry fruit stored at 0, 4.5 or 20C. HortScience 25:1623-1624 Robbins J, Moore PP (1991) Fruit morphology and fruit strength in a seedling population of red raspberry. 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