Characterization and mapping of a rust resistance locus in the common bean landrace G19833.

Abstract

The Andean common bean landrace, G19833 exhibits broad and effective resistance to multiple virulent races of Uromyces appendiculatus, the fungus that causes the rust disease of common bean. In this study, with the combination of high throughput phenotyping and genotyping of large segregating populations, we characterize and map the rust resistance locus present on chromosome Pv04 in G19833. Our results revealed one single dominant gene in G19833 conditioning resistance to the races 16-1 (52), 31-1 (53), 30-1 (55), and 37-1 (84) of U. appendiculatus. Further, we fine mapped the resistance locus in a 747 kb genomic interval using 650 F2 and 1,975 F3 plants from the cross G19833 × Olathe. This region is previously known to have low levels of recombination and contains several disease resistance genes against multiple diseases, including bean rust. To identify candidate genes, we also performed in silico gene expression analysis using the available data from G19833 to identify functional nucleotide-binding sites with leucine-rich repeats (NLRs). Our analysis revealed that some NLR genes were highly expressed across all 11 plant tissues examined, while others showed higher expression in specific tissues. These insights enhance our understanding of rust resistance in common beanand will facilitate the development of cultivars with durable rust resistance.