Genetic Resistance to White Mold Derived From Multiple Sources of Common and Scarlet Runner Bean.

Genetic resistance to white mold (caused by Slerotinia sclerotiorum Lib de Bary) has been reported in both common (Phaseolus vulgaris L.) and scarlet runner (P. coccineus L.) beans. Two F_4:5 recombinant inbred line (RIL) populations were developed from common and scarlet runner bean parents.  The RIL populations had approximately 200 lines each. The objectives of the research were to screen the lines for reaction to WM and validate previously identified molecular markers associated with resistance in the parentage of the populations. Mean white mold scores ranged from 4.2 to 8.8 among lines in the populations. Polymorphic molecular markers were associated with resistant QTL found previously.  These results indicate that molecular markers from two Phaseolus species can be used to introgress resistance to white mold into commercial common bean germplasm.