Dry Bean Breeding

--NDSU--The dry bean breeding and genetics program is focused on the development of high yielding, disease and stress resistant cultivars with upright architecture, and improved canning quality in 10 commercial seed classes for production in Michigan. The research work is an ongoing investigation where genetic stocks at different stages of development exist in all commercial classes and new varieties are released after adequate testing.

Breeding lines are tested and selected in different environments and evaluated for disease resistance under natural pressure in the field and in the greenhouse. After the early stages of selection, good promising lines are put in preliminary yield trials (PYT) across several locations, which allow practicing another round of selection, this time based on replicated data. Selected promising lines are then included in the advanced yield trials (AYT), also planted in several locations during two or three years. Then, elite lines that perform well in the AYT are entered into variety trials (VT) for three years.

The aid of off-season or winter nurseries makes the process more efficient in terms of time, particularly at the early generations, in which one of the main objectives is to reach homozygozity (lines with homogeneous performance). Current winter nurseries are planted in Puerto Rico, New Zealand, and more recently at south Florida. The time required to develop and release a variety after the initial cross is made is usually 10-12 years, although it may be reduced considerably if off-season nurseries are used. Only through long term commitment and funding for this activity is it possible to integrate several traits and genes of interest and thus, obtain new varieties that will increase productivity of bean growers and to the region in general. A breeding program is the only one able to put together all the research from geneticists, pathologists, physiologists, entomologists, etc, into a concrete and visible product: an improved variety.

The breeding project is using laboratory procedures in an attempt to identify and routinely use molecular markers associated with several genes of interest such as white mold resistance. Breeders could then select for the presence of the associated marker for the desired trait. The dry bean breeding project has shared laboratory space with the barley and oat breeding projects. Work at other laboratories has identified markers associated with three rust resistance genes, anthracnose resistance genes, and BCMV resistance genes, among others. Efforts are focused on white mold resistance introgressed into pinto bean, rust resistance, root rot resistance, anthracnose, and quality traits. As additional markers are identified, it may be possible to select for a number of traits simultaneously using DNA obtained from leaf tissue. We also routinely use molecular markers to evaluate for the presence of genes resistant to bean common mosaic virus and rust. We hope to continue doing this for other traits as long as it shows an advantage either in costs or in efficiency within the project (time and/or space).

Recent research activities include assessment of new market classes of dry beans, characterization of past cultivars, search for and use of favorable alleles in exotic germplasm, studying cultivar response pattern and inheritance of soil zinc deficiency resistance, introgression of white mold resistance from the secondary gene pool, breeding for great northern and pinto beans, and improvement of common bean landraces of the western U.S. for sustainable farming system.