Tagging and mapping of genes and QTL and molecular marker-assisted selection for traits of economic importance in bean and cowpea

Bean/Cowpea Collaborative Research Support Program (B/C CRSP) scientists have successfully developed integrated consensus maps of the 11 linkage groups (LGs) in both bean (Phaseolus vulgaris L.) and cowpea (Vigna unguiculata L. Walp). The bean map is approximately 1200 cM with some 500 markers and an additional 500 markers shared with other bean maps. The cowpea map spans 2670 cM with over 400 markers. In addition to molecular markers, both maps include map locations of defense genes and phenotypic traits for disease and insect resistance, seed size, color and storage proteins, pod color and those traits associated with the domestication syndrome in bean. Since the bean and cowpea maps were developed independently, LGs with the same number probably refer to non-syntenic groups. Map locations of major resistance genes in bean are revealing gene clusters on LGs B1, B4, B7, and B11 for resistance to bean rust, anthracnose, common bacterial blight and white mold. Gene tagging and marker-assisted selection for disease resistance has progressed to a point where the indirect selection for resistance to a number of major diseases is now routine in bean breeding programs both in the US and overseas