Rust Resistance in the Guatemalan Climbing Bean Germplasm Collection.

 

RUST RESISTANCE IN THE GUATEMALAN CLIMBING BEAN GERMPLASM COLLECTION

Montejo, Luz de María¹., J.M. Osorno¹, P. McClean¹, J. Steadman² and J.C. Villatoro³   

  

 ¹Dept. of Plant Sciences, North Dakota State University. ²Dept. of Plant Pathology, University of Nebraska, Lincoln and ³ Agricultural Institute of Science and Technology of Guatemala

Common bean (Phaseolus vulgaris L.)  is the main source of quality protein, fiber, and iron for Guatemalan's poorest households, where per capita consumption is approximately 13.6 kg per year. However, bean productivity is affected by abiotic and biotic stresses. One biotic factor is bean rust (Uromyces appendiculatus) (Pers) Unger which can cause up to 100% yield losses. In addition, it is problematic due to its abundant genetic diversity for virulence; more than 24 (Ur) rust resistance genes have been formally named in common bean so far. There is limited information about bean rust virulence in many locations of Guatemala, especially at mid-altitude highlands, where climbing beans are mostly cultivated. Climbing beans have received less attention and breeding efforts compared to bush types, but can be a potential source of resistance. The main objectives of this projects are: 1) To identify the race diversity of bean rust from the Western Highlands in Guatemala; 2) to evaluate disease reaction of the climbing bean in Guatemalan germplasm to rust races from Guatemala and North Dakota (USA); 3) to identify genomic regions associated with rust resistance and 4) to identify reliable molecular markers that could be used in Markers Assisted Selection (MAS). A recent study conducted at this region found six different virulent patterns across 12 locations showing the high rust diversity in Guatemala. During the 2015 growing season, 23 bean rust samples were collected from 11 locations across three departments in the Western Highlands. Pathogen characterization was performed by single pustule inoculation on a set of 12 differential lines and two races were identified: 63-1 and 31-1.  These two races from Guatemala and race 20-3 from North Dakota (USA) will be used to evaluate the climbing bean germplasm. Disease reaction of each plant will be recorded 10-14 days after inoculation using the 1 to 6 scale. Phenotypic results will be associated with genotypic information by Genome Wide Association Studies (GWAS) using 172,000 SNP markers.