PROGRAM OBJECTIVES

Dry Bean (Phaseolus vulgaris) Breeding and Genetics Program

Principal Investigator:
James D. Kelly,
Crop and Soil Sciences, Michigan State University

The dry bean program focuses on the breeding of navy, black, pinto, great northern, light red kidney, dark red kidney, cranberry, white kidney, yellow eye, and pink bean market classes for yield, adaptation, plant architecture, disease resistance, stress tolerance, canning quality, and sustainable production in Michigan (Kelly, 2000) . Since its inception in the early 1900’s the program has released 42 cultivars and participated in the release of 60 germplasm lines. Different bean classes present unique and challenging problems in the improvement of yield, quality, and disease resistance and plant architectural traits. Since kidney and cranberry beans belong to the Andean gene pool that is genetically distinct from Middle American gene pool (navy, black, pinto beans), the effective utilization of Middle American germplasm as genetic donors for improvement in kidney and cranberry beans has been hindered. Breeding methods that optimize integration between gene pools and the wild species are being investigated (Kelly et al., 1998, 1999).

One major focus of the program has been the study of the disease resistance in the same ten commercial classes. The major pathogens endemic in the humid Midwest include rust, anthracnose, mosaic virus, white mold, root rots and bacterial blight. Pathogenic variability and the occurrence of new races of common pathogens (Balardin et al., 1997) combined with a lack of adequate levels of genetic resistance in certain bean classes is a major research challenge. To facilitate breeding for disease resistance, molecular markers tightly linked to the different resistance genes have been developed to permit gene pyramiding and allow for simultaneous selection of multiple disease resistance. Our research group has successfully identified 13 RAPD and SCAR markers tightly linked to 10 major resistance genes that control resistance to three pathogens, (Kelly and Miklas, 1998). Our current focus is on the refinement of marker-aided breeding for disease resistance in beans (work presented at Conference on Durable Disease Resistance in Wageningen, Holland). Since other needed resistance traits are complex and quantitatively inherited, research to develop markers associated with the quantitative trait loci (QTL) controlling resistance to drought (Ramirez and Kelly, 1998), root rots (Schneider and Kelly, 2000, 2001) and white mold (Kolkman and Kelly, 2000, 2002, 2003) is currently being conducted by graduate students in the program.

Graduate student opportunities also exist in the area of genomics related to the breeding for tolerance to biotic and abiotic stresses in bean. Research underway includes the sequencing of resistance gene candidates (Melotto and Kelly, 2001), SSR and AFLP marker development for traits related to disease resistance and drought stress, which is the major abiotic stress of beans under study in our lab (Ramirez and Kelly, 1998; Schneider et al.1997).

Our international research activities funded through the Bean/Cowpea Collaborative Research Support Program (CRSP) have focused on the use of marker-assisted selection in breeding beans for drought and disease resistance in Mexico and Central America (Schneider et al., 1997). Interested students have the opportunity to conduct research overseas. A five-year renewal proposal that will focus on marker-aided strategies to improve beans for tolerance to abiotic and biotic stress in Latin America will be been submitted to USAID in 2001 (Frahm et al., 2003).

Selection for dry seed and processing quality traits. Since beans are consumed directly by humans, they must meet minimum standards for both dry seed and processed seed quality. Over 90% of navy and kidney beans are canned and an increasing large percentage of pinto and great northern beans are now processed. In addition to selection for dry seed traits such as size, shape, and color, all new germplasm must also be evaluated for processing characteristics. Characteristics include: hydration ratio, washed drained weight ratio, processed color, and shear press texture. The complex inheritance of these traits coupled with the delay due to inbreeding prior to evaluation suggests the possibility of developing linked markers to assist in the early generation selection for improved processing quality (Walters et al., 1997; Posa-Macalincag et al., 2002).