White mold–resistant interspecific common bean germplasm lines VCW 54 and VCW 55

Interspecific breeding lines (IBL) VCW 54 (Reg. No. GP-276, PI 655531) and VCW 55 (Reg. No. GP-277, PI 655532) of common bean (Phaseolus vulgaris L.) resistant to white mold [WM; caused by Sclerotinia sclerotiorum (Lib.) de Bary] were jointly developed at the University of Idaho-Kimberly Research and Extension Center and Colorado State University, Fort Collins, CO. The Agricultural Experiment Stations of Idaho and Colorado released VCW 54 and VCW 55 on 10 Dec. 2008. Both IBL were derived from congruity backcrossing between small-seeded tropical black bean cultivar ICA Pijao and P. coccineus L. accession G 35172. ICA Pijao has an indeterminate upright growth habit Type II and resistance to bean common mosaic virus and some races of rust pathogen, and tolerance to bean golden mosaic virus (BGMV). G 35172 has large purple-mottled seeds, an indeterminate climbing growth habit Type IV, and resistance to BGMV. G 35172 also is variable for WM reaction. VCW 54 has scarlet flowers, purplish black seed, and the highest WM resistance. VCW 55 has white with pink-striped flower, black seed, and an intermediate level of WM resistance. Both IBL also have growth habit Type II, small seeds, and are late maturing, requiring ≥100 d from planting to maturity in southern Idaho. White mold resistance from VCW 54 and VCW 55 should be pyramided with WM resistance from across Phaseolus species and introgressed into common bean cultivars using appropriate crosses, population sizes, and disease screening and selection methods.This research was supported by the USDA-ARS National Sclerotinia Initiative Grant No. 58-5442-2-256 “Introgressing White Mold Resistance from the Secondary Gene Pool of Common Bean” from 2002 to 2009. The authors also thank Marie Dennis and Richard Hayes for management of the greenhouses at Kimberly, ID, and to Craig Robinson for field plot management at Parma, ID.USDA-ARSPeer reviewe