Interspecific introgression effects on bean breeding germplasm

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Conventional wisdom suggests that modern crops would benefit from efforts to broaden their genetic diversity. For example, common dry bean (Phaseolus vulgaris) is believed to have been domesticated, independently, in two geographic regions with losses of genetic diversity during each domestication event. To increase the genetic diversity of crop germplasm and introduce new traits plant breeders have made crosses between exotic materials and conventional varieties. Our breeding program made interspecific crosses between P. vulgaris and Phaseolus acutifolious to introduce resistance to infection by Xanthomonas axonopodis pv phaseoli, which causes bacterial blight, into dry bean. The first bacterial blight resistant variety derived from this interspecific cross was OAC Rex. The proposed research program will test the hypothesis that the interspecific introgression had various effects on the bean genome that are manifested in changes in gene number, chromosome structure and agronomic characteristics. In particular, the study will i) examine the patterns of introgression of P. acutifolius genes into the OAC Rex genome, ii) test the functionality of the introgressed genetic material and iii) determine if there are changes in agronomic traits (such as crop yield) that are attributable to the introgressed DNA. These studies will enhance the general understanding of the consequences of interspecific introgresssion on genome structure in an important cultivated species and help to assess the value of efforts to broaden crop diversity for crop improvement.