Genetic analysis of victorin sensitivity and identification of a causal nucleotide-binding site leucine-rich repeat gene in phaseolus vulgaris

Abstract

Cochliobolus Victoria, the causal agent ofVictoria blight, is pathogenic due to its production of a toxin called victorin. Victorin sensitivity in oats, barley, Brachypodium spp., and Arabidopsis has been associated with nucleotide-binding site leucine-rich repeat (NLR) genes, a class of genes known for conferring disease resistance. In this work, we investigated the sensitivity of Phaseolus vulgaris to victorin. We found that victorin sensivity in Phaseolus vulgaris is a developmentally regulated, quantitative trait. A single quantitative trait locus (QTL) accounted for 34% of the phenotypic variability in victorin sensitivity among Stampede × Red Hawk (S×R) recombinant inbred lines. We cloned two NLR-encoding genes within this QTL and showed one, Phvul05G031200 (PvLOV), confers victorin-dependent cell death when overexpressed in Nicotiana benthamiana. Protein sequences of PvLOV from victorin-sensitive and the victorinresistant bean parents differ by two amino acids in the leucinerich repeat region, but both proteins confer victorin-dependent cell death when overexpressed in N. benthamiana.