Comprehensive Screening of Common Bean (Phaseolus vulgaris) Germplasm Reveals Diverse Resistance to Soybean Cyst...

This report summarizes evaluation of 1,220 USDA germplasm accessions of common bean (Phaseolus vulgaris) for resistance to soybean cyst nematode (SCN; Heterodera glycines [HG]) across eight SCN populations (representing five HG types) conducted in Minnesota (MN), Illinois (IL), and North Dakota (ND). Of the 694 accessions tested with replicated plants in MN, 90 were identified as resistant (female index [FI] < 10), and 260 were identified as moderately resistant (10 ≤ FI < 30) to one or more SCN populations. Incorporating published data from studies in IL and ND along with all MN data, 250 accessions exhibited resistance (FI < 10), and 500 showed either resistance or moderate resistance (FI < 30) across different SCN populations. No SCN-resistant genotypes were found in the MN common bean breeding program. Cluster analysis based on FI values revealed distinct groups of accessions with varying resistance profiles, suggesting the presence of genetic diversity in SCN resistance. Six accessions exhibited strongest resistance across multiple SCN populations, highlighting their potential as sources for breeding widely adapted SCN-resistant common bean cultivars. Based on the data of resistance to different SCN HG types, the mechanisms of SCN resistance in common bean appeared to be different from that in soybean. However, inconsistencies in resistance across SCN populations and test conditions underscore the need for further testing under uniform conditions. Because only approximately 10% of the USDA common bean collection has been evaluated, continued screening efforts are essential to explore the remaining germplasm and identify the best sources of SCN resistance for integration into breeding programs.