White mold disease (WM) of common bean (Phaseolus vulgaris L.), caused by Sclerotinia sclerotiorum (Lib.) de Bary, reduces crop yield and quality throughout the United States. The development of cultivars with resistance to WM would be facilitated by the identification and use of molecular markers linked to resistance genes. The objectives of this research were (i) to characterize WM reaction in a recombinant inbred line (RIL) population derived from a cross between resistant and susceptible germplasm, (ii) to validate the effect of a previously reported quantitative trait locus (QTL) for WM resistance, and (iii) to locate additional QTL associated with WM resistance. A RIL population that consisted of 94 lines was derived from a cross between G122 (resistant) and CO72548 (susceptible). The population was evaluated for WM reaction in three greenhouse tests and one field environment, and for molecular markers throughout the genome. Two RIL were identified with higher resistance levels (P < 0.05) than the resistant parent G122. A previously reported QTL on linkage group B7 was significant (P < 0.01) in single‐factor analysis of variance, but not with composite interval mapping. Five QTL for resistance to WM were found (likelihood odds ratio [LOD] > 2.7) on linkage groups B1, B2b, B8, and B9. The QTL were contributed from both parents and together accounted for 48% of the phenotypic variation (R2). For field resistance, one QTL (R2 = 12%) on linkage group B8 was detected. These results confirm polygenic resistance to WM in common bean.

No abstract

Common bean (Phaseolus vulgaris L.) is an important staple food crop in households worldwide. Genotype and location influence phenotypic nutrient composition. However, there are limited data on the magnitude of this variation for common bean yield and nutritive value. The objective of this study was to determine the effect of location on yield and seed nutritional composition. Four globally important varieties (dark red kidney/‘Montcalm’, great northern /‘Taurus’, black /‘Eclipse’ and yellow Mayocoba/‘MY06326’) were planted for two years in four locations (Iowa, Colorado, Michigan, in the USA, and Masaka, Uganda). Yield and seed weight differed among locations and varieties. Yield in Colorado and Michigan was 42% and 56% higher than in Iowa and 76% and 81% greater than in Uganda, respectively. Eclipse had greater yield than Taurus (6%), MY06326 (16%), and Montcalm (35%). Concentration of P, K, Mg, S, and crude protein (CP) differed among varieties. Montcalm had 18%, 7%, and 4% greater P concentration and 13%, 9%, and 5% greater CP than Eclipse, MY06326 and Taurus, respectively. The location × variety interaction was significant only for seed Zn concentration. Despite differences in edaphic factors among locations, elemental concentrations other than Zn were comparatively stable among locations. Stability in seed elemental concentrations across locations and environments is important knowledge for better understanding human nutrition and malnutrition.

Seven races of Fusarium oxysporum f. sp. phaseoli Kendrick and Snyder (Fop) cause Fusarium wilt (FW) disease of common bean (Phaseolus vulgaris L.). FW occurs worldwide and has recently become a serious disease in the central and western USA. The objectives of this research were to identify new sources of resistance to Fop, characterize the Central/South American (CA/SA) Phaseolus Core Collection for reaction to races 1, 4, and 5 Fop and determine if a previously reported sequence characterized amplified region (SCAR) molecular marker would be useful to identify resistance among accessions that make up the CA/SA Core Collection. Seedlings from the CA/SA Core Collection were screened for reaction by a root dip inoculation procedure. Among accessions evaluated for reaction to race 1 Fop, 21 were resistant, 47 intermediate, and 126 susceptible. Fifteen accessions were resistant to race 4, 61 intermediate, and 114 were susceptible. Nine accessions were resistant to both races 1 and 4, and five of the nine (PI 207373, PI 307802, PI 308908, PI 309877, PI 310842) were also resistant to race 5 Fop. All accessions resistant to races 1, 4, and 5 of Fop were characterized as Middle American, which suggests that resistance to multiple races of Fop should be more prevalent in germplasm from Middle America. The SCAR marker previously developed to identify a quantitative trait locus (QTL) associated with resistance to Fop was not associated with resistance in the Core Collection.

D rought stress reduces dry bean seed yield in most production regions worldwide (White and Singh, 1991). The release of pinto bean (Phaseolus vulgaris L.) germplasm CO46348 (Reg. No. GP-275, PI 651500) will provide plant breeders with drought-tolerant, pinto bean germplasm that takes advantage of a full growing season (95-98 d) and has high yield potential, excellent pinto seed quality, and resistance to rust caused by Uromyces appendiculatus. CO46348 was developed by the Colorado Agricultural Experiment Station in cooperation with the University of ABSTRACT Drought stress reduces dry bean (Phaseolus vulgaris L.) yield in more than 60% of the production regions worldwide. Pinto bean germplasm line CO46348 (Reg. No. GP-275, PI 651500) was developed by the Colorado Agricultural Experiment Station in cooperation with the University of Idaho and USDA-ARS and released 1 Apr. 2007. CO46348 is a drought-tolerant pinto bean germplasm with a 95 to 98 d growing season, high yield potential, excellent pinto seed quality, and resistance to rust caused by Uromyces appendiculatus. The complete pedigree of CO46348 is unknown; however, it was derived from a single cross made in 1989 with the pinto cultivar Othello as the female parent. Othello is a short-season pinto cultivar released in 1987 that combines excellent pinto seed color and resistance to some strains of bean common mosaic caused by Bean common mosaic virus (a potyvirus).