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James L. Brewbaker

widely studied as clones using vegetative propagation methods of Shi and Brewbaker (2006) . Description Yield and psyllid resistance. Interspecific hybrids of L. leucocephala ssp. glabrata × L. esculenta are arboreal, vigorous vegetatively, and

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Desire Djidonou, Xin Zhao, Jeffrey K. Brecht, and Kim M. Cordasco

dependent on the rootstock genotypes ( Ruiz et al., 1997 ). Both tomato hybrid and interspecific tomato hybrid rootstocks are typically used for tomato production ( King et al., 2010 ). Grafted tomato plants with interspecific hybrid rootstocks exhibit more

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Shawna L. Daley and Richard L. Hassell

commonly used in Asia and Europe, bottle gourd ( Lagenaria sicereria cv. Emphasis) (Syngenta Seeds, Boise, ID) and interspecific hybrid squash ( Cucurbita maxima × Cucurbita moschata cv. Carnivor) (Syngenta Seeds), were sown in 72-cell, TLC polyform

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Mihoko Tamura, Ryutaro Tao, and Akira Sugiura

Interspecific hybrids between Diospyros glandulosa (2n = 2x = 30) and D. kaki cv. Jiro (2n = 6x = 90) were produced by electrofusion of protoplasts. Protoplasts were isolated from calli derived from leaf primordia, fused electrically, and cultured by agarose-bead culture using modified KM8p medium. Relative nuclear DNA contents of calli derived from fusion-treated protoplasts were determined by flow cytometry. One-hundred-forty-nine of 166 calli obtained had the nuclear DNA content of the sum of those of D. glandulosa and D. kaki cv. Jiro. RAPD analysis showed that the 149 callus lines yielded specific bands for both D. glandulosa and D. kaki cv. Jiro and they appeared to be interspecific somatic hybrid calli. Shoots were regenerated from 63 of the 149 interspecific hybrid calli. PCR-RFLP of chloroplast DNA analysis, flow cytometric determination of nuclear DNA content, and RAPD analysis revealed that the 63 interspecific hybrid shoot lines contained nuclear genome from both the parents but only chloroplast genome from D. glandulosa. Microscopic observation of root tip cells confirmed that somatic chromosome numbers of the interspecific hybrids were 2n = 8x = 120.

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W. Alan Erb and Richard K. Lindquist

Selected interspecific hybrids between Lycopersicon esculentum and 11 wild species accessions were evaluated for level and type of resistance to Trialeurodes vaporariorum. The interspecific hybrids were clonally propagated and evaluated for antibiosis to non-sexed adult whiteflies, larvae development to the 3rd or 4th instar and reproduction of a second generation of adults. The test unit was a fully mature and expanded leaf containing only 4 leaflets and an 11 cm stem section sitting in a bottle of weak nutrient solution. One detached leaf-stem section from each entry was randomly placed in one of 12 set positions of a bottle rack. Leaflets were infested by placing 5-10 adult whiteflies on 2 leaflets/entry in small leaf cages for 24 or 48 hrs. Adult mortality was determined after 24 & 48 hrs and instar counts were taken after 14 & 21 days. Second generation reproduction was determeind by placing the 2 leaflets with the highest number of 3rd & 4th instar larvae in a petri-dish and recording adult emergence over a 5-18 day period. Some of the hybrids were more resistant and others were more susceptible that the L. esculentum parent. Resistance was manifested in greater adult antibiosis, reduced number of developed larvae and reduced adult emergence.

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James R. McKenna and Lynn Epstein

Crown gall, caused by the common soil-borne bacterium Agrobacterium tumefaciens, can be an economic problem in walnut nurseries and production orchards in California. The principal rootstocks used for commercial walnut production in California are the native Northern California black walnut, Juglans hindsii, and “Paradox,” which are interspecific hybrids between a black walnut, primarily J. hindsii, as the maternal parent, and J. regia, the English walnut, as the paternal parent. Recent evidence has shown that some commercial black walnut trees producing Paradox hybrid seedlings are actually hybrids between J. hindsii and two other North American black walnut species, J. major and J. nigra. Here, we document that there was a higher incidence of crown gall on Paradox (J. hindsii ×J. regia) than on J. hindsii in three sites with natural soil inoculum. Paradox seedlings (with a female parent that was primarily J. hindsii with some J. nigra) inoculated with A. tumefaciens on the roots during transplanting had a higher incidence of crown gall than either J. hindsii or J. regia. When stems were inoculated with A. tumefaciens, J. hindsii ×J. regia populations had significantly larger galls than either J. hindsii or J. regia. Similarly, in stem inoculations on four out of six Paradox genotypes with a hybrid black walnut maternal parent, the progeny produced significantly larger galls than either J. hindsii or J. regia. However, two Paradox populations from black walnut hybrids that contained J. major, J. nigra, and J. hindsii produced galls that were no different in size than in the black walnut species and J. regia. Results suggest that J. regia and black walnut species are less susceptible to crown gall than most Paradox populations.

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Cecil Pounders, Tim Rinehart, and Hamidou Sakhanokho

interspecific hybrid cultivars ( Egolf, 1981a , 1981b , 1986a , 1986b , 1987 , 1990 ; Pooler, 2006a ; Pooler and Dix, 1999 ) that successfully combined the powdery mildew resistance of L. fauriei with other desirable horticultural traits from L. indica

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Chun-Yan Han, Gui-Fen Luo, Li Ji, Wei-Bang Sun, Xu-Yang Fu, and Cong-Ren Li

in Hunan ( Liao, 2007 ). Three cultivars, including M . ‘Yujin’, M . ‘Danxin’, and M . ‘Qinfang’, are interspecific hybrids between M. crassipes and M. yunnanensis . M. calcicola C. Y. Wu is an evergreen tree native to the subtropical

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Thomas G. Beckman, Jose X. Chaparro, and Wayne B. Sherman

. ‘MP-29’ also provides a marked reduction in tree vigor compared with peach seedling type rootstocks and may prove useful as a semidwarf rootstock where a less vigorous tree is preferred. Origin ‘MP-29’ is an interspecific hybrid developed by the U

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Yuji Noguchi, Tatsuya Mochizuki, and Kazuyoshi Sone

The use of wild species as breeding materials was tried for expanding hereditary variation in strawberry. Some interspecific hybrids setting large fruits with peculiar aroma have been bred by pollination of F. vesca to F. xananassa. Although Asian wild diploid strawberries such as F. nilgerrensis or F. iinumae have not been exploited as a breeding material until the present, the crossing test between cultivated strawberries (8x) and the Asian wild strawberries (2x) were attempted. The interspecific hybrids originated from pollination of F. nilgerrensis or F. iinumae to F. xananassa cv. `Toyonoka' were all sterile pentaploids. By in vitro colchicine treatment of these sterile hybrids for chromosome doubling, many fruiting interspecific hybrids were produced. In particular, some superior hybrids were obtained from `Toyonoka' × F. nilgerrensis. From the results of RAPD analysis, the interspecific hybrids had the fragments specific for both parents. While their morphological characters were close to `Toyonoka', they had some characters from F. nilgerrensis, such as numerous hair on their petioles and peduncles. Their fruits have good characters that are same level of cultivated strawberry about size, Brix, acidity, and vitamin C content. The flesh is soft and skin color is pale pink. The aroma components are resemble F. nilgerrensis, and enrich ethyl acetate. The fragrance of interspecific hybrid like peach is characteristic.