Contribution of Genetic Diversity to the Improvement of Dry Edible Beans.

Progress in the genetic improvement of dry edible beans (Phaseolus vulgaris L.) should be measured within the seed market class and the cropping system used to produce the crop. During the past 20 years seed yield of Middle American bean market classes have increased. Plant breeders have utilized crosses between the Durango and Mesoamerican bean races to improve agronomic traits and to enhance disease resistance of pinto and Great Northern beans. Crosses between the Middle American and Andean gene pools have been used to develop bean breeding lines with more durable resistance and to improve agronomic traits of Andean bean market classes. Wild beans are an important source of pest resistance and may prove to be a source of novel genes for seed yield. Interspecific crosses have already been used to increase common bacterial blight [Xanthomonas axonopodis pv. phaseoli (Smith) Dye] resistance of dry edible bean cultivars. Valuable sources of resistance to disease, pest and abiotic stress have been identified in tepary bean (Phaseolus acutifolius A. Grey) and scarlet runner bean (Phaseolus coccineus L.). Many of these traits will likely be introgressed into dry edible beans. An enhanced capacity to map traits may facilitate the utilization of genetic diversity to improve dry edible beans.