Gene mapping and identification of candidate genes associated with fomesafen herbicide tolerance in Mung bean (Vigna radiata L.)

Herbicides are widely applied for weed control in mung bean cultivation. Developing new varieties with herbicide resistance is critical for weed management in mung bean. In this study, a recombinant inbred line (RIL) population, developed from a cross between the fomesafen resistant variety LZ177 and the fomesafen susceptible variety LD235, was used to map the genes related to fomesafen herbicide resistance. The initial mapping performed with genetic mapping and BSA-seq revealed a candidate region of 1.17 Mb on chromosome 11. RNA-seq were performed using a residual heterozygous line 198 resistant (RHL198-R) and susceptible (RHL198-S) line at 0, 12, 24, 48, and 72 h after fomesafen treatment. Gene mapping, BSA-seq, and RNA-seq identified a total of 13 potential candidate genes, of which one-base (A) insertion/deletion in the exon of jg37117 , which encode a tau class glutathione S-transferase U18 (GSTU18), was determined to be the most promising candidate gene. We detected an A deletion in the exon of VrGSTU18 in the susceptible lines, which are more susceptible to fomesafen than those lacking this deletion. VrGSTU18 was cloned from LZ177 and subsequently transferred into Arabidopsis. Compared with WT plants, the VrGSTU18 -overexpressing T ₁ transgenic seedlings were more resistant to fomesafen herbicide. This study identified candidate gene potentially conferring resistance to fomesafen herbicide, providing a theoretical foundation for future research in mung bean breeding.