Molecular mapping and identification of candidate gene conferring organophosphate‐sensitive reaction in sorghum (Sorghum bicolor)

Abstract Some sorghum cultivars are sensitive to organophosphate insecticides, which cause red to purple injury spots and, in severe cases, leaf death. Sensitivity to organophosphates is conditioned by a single locus on chromosome 5. We constructed a high‐density genetic map around the locus, termed osr , using DNA markers, and delimited osr to a 377‐kb region on the short arm of chromosome 5. Sequence analysis of this region predicted 19 gene candidates. Four of the candidates are homologous to a disease resistance NBS‐LRR gene. mRNA‐Seq analysis of gene expression and SNPs from two resistant cultivars (‘JN43’ and ‘Greenleaf’) and one sensitive cultivar (‘Nakei MS3B’) suggest that one or more members of this NBS‐LRR gene family are osr . Our results suggested that the recessive allele of osr results in sensitivity to OP insecticides.