1a. Objectives (from AD-416)
The major and long-term objectives of this project are 1) to identify and characterize disease resistance genes in common bean for the management of the soybean rust pathogen (Phakopsora pachyrhizi), (2) to identify and characterize disease resistance genes in common bean for the management of common bean rust (Uromyces appendiculatus), and 3) to use newly discovered and other disease resistance genes to develop common bean germplasm lines with multiple resistances to common bean and soybean rusts and other highly variable pathogens.
1b. Approach (from AD-416)
To identify and characterize disease resistance genes for soybean rust (SBR) control in common bean, a sub sample of the common bean core collection will be evaluated. This core collection will have about 250 bean accessions from the Andean (five countries) and Mesoamerican (six countries) gene pools. Soybean accessions will be included as checks. Several isolates of the SBR pathogen from different countries in Africa, Asia, and South America, and from the United States, will be used to inoculate the common bean accessions. SBR resistant and susceptible accessions will be crossed to characterize the inheritance of SBR resistance and to search for molecular markers linked to the SBR resistance genes. Appropriate populations (F2, RILs, etc.) for these types of studies will be developed and inoculated with selected isolates of the SBR. Leaf tissue from each F2 plant or other appropriate progeny plant will be collected for DNA extraction and the identification of molecular markers linked to SBR resistance genes. To determine yield reduction on common bean caused by SBR, dry bean plots will be established under field conditions in collaboration with scientists from the United States and Brazil. Two locally adapted dry bean cultivars will be used. Locally adapted soybean cultivars will also be included for comparison. Similar methodologies and approach will be used for the identification and characterization of resistance genes in common bean for the control of common bean rust. All the newly discovered genes for resistance to both rusts will be used in the development of new bean cultivars with commercial bean seed type and broad resistance to rusts and other important common bean pathogens.
3. Progress Report
Progress was made in a collaborative project to combine highly desirable attributes for the sustainable production of pinto beans in the western region and High Plains of the United States. Pinto bean is the largest market class of dry edible beans in the U.S. Two of the most important attributes of dry bean cultivars include high seed yield and resistance to several major diseases of dry beans. A pinto bean cultivar was developed that combined high yield and several genes for resistance to the pathogens that cause bean rust, bean common mosaic, bean common mosaic necrosis, and the common bacterial blight diseases. The resistance to the highly variable bean rust pathogen in this cultivar is conditioned by two very different rust resistance genes; one from the Andean and the other from the Mesoamerican gene pools of the common bean. This project was conducted in close collaboration with scientists from Colorado State University, the University of Idaho, and the USDA-ARS at Prosser, Washington. Progress was made in identifying newly developed common bean cultivars with resistance to two new virulent strains of the bean rust pathogen that emerged recently in North Dakota and Michigan. The appearance of these new strains rendered susceptible many dry bean cultivars that had single rust resistance genes, including “Stampede” a popular and productive pinto bean in North Dakota. To accomplish the objective of providing resistance to new virulent bean rust races, we inoculated plants with specific races of the bean rust pathogen that permitted the identification of pinto bean plants with broad rust resistance to the highly variable rust pathogen as well as resistance to the two new races that emerged in North Dakota and Michigan. Using this methodology we have identified bean plants that are sister lines of Stampede but have additional rust resistance genes and are resistant to the new strains. Seed of the newly identified rust resistant plants is being increased by scientists at the North Dakota State University for distribution to bean producers. North Dakota and Michigan account for more than half of the dry bean production in the United States.
1. Elucidated the inheritance of two genes for resistance to bean diseases. Anthracnose and angular leaf spot are very widespread and devastating diseases of common bean. We have conducted a study that elucidated how two genes that confer broad spectrum resistance to the pathogens that cause these diseases are inherited. Because the two genes were located very close to each other on one of the common bean chromosomes, they were inherited together. We also identified two molecular markers tagging these two genes that can be used to monitor their presence in bean plants. Thus, the markers will facilitate the development of beans having these genes that will provide greatly enhanced anthracnose and angular leaf spot resistance. The potential impact of the two genes for resistance and of the markers to rapidly identify common breeding lines with simultaneous resistance to anthracnose and angular leaf spot is significant. This research was conducted by researchers at the ARS, Beltsville, MD in close collaboration with scientists from the State University at Maringá in the state of Parana, Brazil and scientists from the University of California-Davis and North Dakota State University.
Goncalves-Vidigal, M., Cruz, A., Garcia, A., Vidigal Filho, P., Souza, L., Pastor Corrales, M.A., Mcclean, P., Kami, J., Gepts, P. 2010. Linkage mapping of the Phg-1 and Co-14 genes for resistance to angular leaf spot and anthracnose in the common bean cultivar AND 277. Theoretical and Applied Genetics. 122:893-903.