ARS | Publication request: Comparative QTL map for white mold resistance in common bean, and characterization of partial resistance in dry bean lines VA19 and I9365-31

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 5, 2010
Publication Date: October 12, 2011
Citation: Soule, M., Porter, L., Medina, J., Santana, G., Blair, M., Miklas, P.N. 2011. Comparative QTL map for white mold resistance in common bean, and characterization of partial resistance in dry bean lines VA19 and I9365-31. Crop Science. 51:123-139.

Interpretive Summary: White mold is the most important disease problem plaguing production of pinto, kidney, snap, and other common bean market classes grown in the U.S. and globally. Natural resistance to this disease is an important component of an integrated control strategy which includes fungicides and cultural practices. Genetics of resistance is complex, which makes it difficult for breeders to obtain cultivars with improved resistance. The work reported here characterizes resistance to white mold derived from two new sources, I9365-31 black bean and VA19 kidney bean. In addition, a comparative genetic map for all the white mold resistance genes identified to date was constructed. The map depicts 21 distinct genomic regions that influence resistance to white mold in common bean. The new genes found and characterized will faciliate breeding for resistance to this destructive pathogen. The comparative linkage map itself provides a blueprint for integrating and interpreting future genetic studies concerning white mold resistance in common bean.

Technical Abstract: White mold caused by the necrotrophic fungus Sclerotinia sclerotiorum (Lib.) de Bary limits common bean (Phaseolus vulgaris L.) production in temperate climates. Disease resistance has been identified, but breeding is hampered by a paucity of resistance sources and complex inheritance, as numerous QTL conditioning partial resistance have been found. Our objectives were to characterize the partial white mold resistance found in breeding lines I9365-31 and VA19, and to construct a comparative linkage map for all the white mold resistance QTL identified to date. Recombinant inbred populations, ‘Benton’/VA19 (BV) and ‘Raven’/I9365-31 (R31) consisting of 79 F6 and 105 F5 RILs, respectively, were evaluated for white mold reaction in multiple greenhouse and field tests. Two QTL were found in BV, WM2.2 expressed in GH (R2=33%) and field (13%), and WM8.3 expressed in field (11%) only; and seven in R31 (WM2.2, WM4.2, WM5.3, WM5.4, WM6.1, WM7.3, WM8.4), three expressed in greenhouse tests and four in the field, and ranging in phenotypic variance from 5 to 52%. These QTL were compared with 26 previously identified QTL, resulting in a comparative linkage map of 35 QTL which coalesced into 21 distinct regions across nine linkage groups. Four QTL found in R31 were novel. SCAR markers associated with WM2.2, WM8.3 and WM7.3 QTL were generated. The comparative linkage map provides a framework for integrating and interpreting future QTL studies concerning white mold resistance in common bean. .