Development of Dry Bean Populations with Possible Resistance to White Mold
April 15, 2003
Department of Plant Pathology
Department of Plant Sciences
North Dakota State University
White mold is a persistent and economically-damaging disease of dry beans in the Northarvest production area. Disease susceptibility is common in accepted cultivars, so the potential for serious economic damage in the future is high. Genetic resistance is the most efficient way to control any disease. With that in mind, the objective of this research is to identify new sources of genetic resistance to white mold in dry bean and to move that resistance into germplasm adapted to the Northarvest region that can be used by the breeding program for future cultivar development.
We began this project by conducting greenhouse tests with dry bean lines previously collected in Mexico and Central and South America to identify those lines with potentially useable white mold resistance. These dry bean lines, collected, maintained, and obtained from the USDA, are genetically different from our varieties. Collectively, they contain potentially valuable sources of genetic resistance for the Northarvest production area. Included in this genetic variability may be new sources of resistance to white mold. Four of the best lines identified from these screens were crossed with Othello, a disease-susceptible Pinto bean cultivar adapted to this region.
A population of approximately 100 to 125 lines was developed in the greenhouse from each of the four crosses with Othello. During the past year, each population was advanced to the F6 generation. F6 lines are genetically stable, like a cultivar. This stability will permit the increase of large amounts of seed of each population that can be used in multiple replicated tests in the field and greenhouse as we screen the populations for resistance to white mold. Also, since they are genetically stable, F6 lines that show promise for white mold resistance can be expected to contribute genetic resistance to the breeding program in a predictable fashion. Adequate seed have been obtained from each F6 population for greenhouse tests next fall and winter. In addition, we will have enough seed to test one population in the field this summer.