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Dale T. Lindgren and Daniel M. Schaaf

and other hybrids. The objective of this report is to summarize the interspecific crosses in the genus Penstemon at the UNL WCREC over 10 years, 1996–2005, and compare those results to other reports in the literature. The majority of species used in

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Joseph Tychonievich and Ryan M. Warner

cultivated Salvia species and to provide information for plant breeders interested in developing hybrid Salvia , our objectives were to: 1) test the interspecific crossability of a select number of S alvia species from different clades and with different

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Bob Bors and J. Alan Sullivan

Fragaria vesca has been introgressed into F. ×ananassa in the form of decaploids and synthetic octoploids. As F. vesca is self-incompatible and crosses with most diploid Fragaria species when used as a female parent, it could serve as a bridge for introgression of additional genetic material. A primary goal of this study was to screen selections of F. vesca for interspecific crossability among diploid species. The F. vesca collection included 10 cultivars of the alpine strawberry, F. vesca var. semperflorens, as well as 30 wild runnering types gathered from around the world. The following diploid species were represented by one to three genotypes each: F. viridis, F. nubicola, F. nipponica, F. nilgerens, F. iinumae, F. daltoniana, F. gracilis, as well as two unnamed species from China. Fragaria vesca was used as the female parent and the other species provided the pollen. Crossing took place in the greenhouse, with one pollination occurring during the “popcorn” or “balloon” stage. Germination was performed in vitro using cut achenes shortly after fruit ripening. The alpine strawberry cultivars were easier to cross than wild selections of F. vesca. Their continuous blooming habit combined with higher positioning of flowers allowed for easier and perhaps less-damaging emasculation. Crossability, as measured by seed set and germination, was more variable in wild-type F. vesca and generally lower than alpine strawberry cultivars.

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Hongwen Huang, Fenny Dane and Joseph D. Norton

Linkage relations among eight isozyme genes, Acp-3, Est-1, Est-5, Prx-1, Prx-2, Prx-3, Me and Adh, and two morphological markers, Inh, and Twh, were investigated in one F2 and two BC1 families of interspecific crosses between the American chestnut (Castanea dentata) and the Chinese chestnut (C. mollissima). Inh was found to be consistently linked with Prx-1 and Est-5 in all families. The order of these three genes was determined to be-Ihn--Prx1--Est5. In addition, four other gene pairs, Acp3--Inh, Acp3--Prx1, Me--Inh and Twh--Inh were found to be linked in one of the three families investigated. The four isozyme genes and two morphological marker genes were tentatively integrated into one linkage group with the following gene order Acp3--Me--Twh--Inh--Prx1-Est5. This study demonstrated that isozyme genes can be integrated with morphological marker genes into a single linkage map without the need for additional crosses.

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M.E. Scott and T.E. Michaels

Effective genetic resistance to common bacterial blight [Xanthomonas campestris pv. phaseoli (Smith) Dye] is not present in common bean (Phaseolus vulgaris L.) cultivars grown in Ontario. Foliar symptoms and seed yield of white pea bean breeding lines from a P. vulgaris/P. acutifolius interspecific cross in the presence and absence of common blight were evaluated. In inoculated plots, seven of the 20 breeding lines did not differ significantly in severity of foliar symptoms from the most resistant controls, XAN 159 and XAN 161. The most susceptible lines tended to have the highest yield when grown under disease-free conditions (r = 0.61 and 0.49 at two locations). However, the susceptible lines showed an average yield loss of 25% when disease-free and inoculated plots were compared, while resistant lines had little or no yield loss. The most severely infected lines tended to have the greatest loss in yield (r = 0.72 and 0.53 at two locations). A resistant breeding line from this study is available as OAC 88-1.

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Dario J. Chavez and Paul M. Lyrene

confounding factor by dividing individual plants into two parts to compare intraspecific crosses ( V. darrowii × V. darrowii and V. corymbosum × V. corymbosum ) with interspecific crosses [ V. darrowii × V. corymbosum and reciprocal, and ( V. darrowii

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Gustavo R. Rodríguez, Guillermo R. Pratta, Roxana Zorzoli and Liliana A. Picardi

A cross was performed between Lycopersicon esculentum Mill. `Caimanta' and L. pimpinellifolium (Jusl.) Mill. accession LA722. Divergent-antagonistic selection for fruit weight and shelf life started in the F2 generation. Fruit shelf life showed transgressive segregation in this F2 generation. The selection process continued until the F6 generation, but we found that only fruit weight was responsive to selection. Seventeen recombinant lines (RILs) were analyzed for both traits. Nine of these RILs were obtained by the selection process. The other eight RILs were obtained by selfing without selection from the same F2 generation to assess random drift. Highly significant differences were found among these RILs for both fruit weight and shelf life. Random drift was as important as selection in producing different genotypes. Although fruit shelf life showed null response to selection in this interspecific cross, selfing and selecting has generated a new population of 17 recombinant genotypes for both fruit weight and shelf life. This experiment has demonstrated that wild tomato species offer breeders another possibility to enhance the genetic variability for fruit shelf life and fruit weight in tomato germplasm.

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Sierd Zijlstra, Coen Purimahua and Pim Lindhout

Crossing barriers between white- and purple-flowered species were examined. Four accessions of Capsicum annuum and three of C. pubescens were reciprocally crossed with one to four accessions of C. baccatum, C. cardenasii, C. chacoense, C. chinense, C. eximium, C. frutescens, C. galapagoense, and C. praetermissum. Capsicum chacoense is the only white-flowered species that inhibits C. annuum pollen tube growth but allows C. pubescens pollen tube penetration into the egg cell. Capsicum cardenasii and C. eximium exhibit similar crossabilities with C. annuum and C. pubescens: pollen tubes of C. cardenasii and of C. eximium can penetrate the egg cells of C. annuum but not vice versa, and pollen tubes of C. pubescens can penetrate the egg cells of C. cardenasii and of C. eximium but not vice versa.

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Mark J. Bassett and Phillip N. Miklas

required, and the scarlet flower color gene, Am , is probably required ( Bassett, 2003b ). Lamprecht (1941) used ‘Painted Lady’ in his inheritance studies of interspecific crosses with P . coccineus , noting that ‘Painted Lady’ had “two

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Debbv M. Filler, James J. Luby and Peter D. Ascher

Three classes of crosses using four genotypes of V. riparia (wild Riverbank grape) as maternal parents were evaluated for evidence of reproductive expression of genetic incongruity. The classes were: I V. riparia x V. vinifera cultivars (European domesticated grape); II V. riparia x French Hybrids (complex interspecific hybrids); III V. riparia x V. riparia. Percent fruit set and seeds per berry were recorded for two years. If incongruity is a factor in interspecific grape crosses, then the values for these traits would be expected to be lower in classes I and II than in class III. Analysis of variance indicated significant differences for some half-sib families. Fruit and seed set were lower in classes I and II than in class III, suggesting that incongruity is operative in wide grape crosses. In the process of creating French hybrids, genomes of several species came together over generations of hybridization. In concert with selection for fertility, repeated interspecific genomic exposure would be expected to have ameliorated the effects of initial incongruity between American species and V. vinifera, increasing their value as genetic bridges in breeding programs.