Yellow nutsedge WRI3/4-like gene improves drought tolerance in Arabidopsis thaliana by promoting cuticular wax biosynthesis

Abstract Using RACE PCR, full length WRI1-like gene was amplified from yellow nutsedge. Conserved domain and phylogenetic analyses suggested it as WRI3/4-like gene. Tissue-specific expression data showed the highest expression in leaves, followed by roots while the lowest expression was detected in tuber. Transgenic Arabidopsis plants expressing nutsedge WRI3/4-like gene showed significantly improved tolerance to both PEG-simulated drought stress and real dehydration, compared with the wild type (WT). Under normal growth conditions, the expressions of key fatty acid biosynthesis genes was not significantly different between WT and transgenic lines, while the expressions of genes involved in cuticular wax biosynthesis was significantly higher in transgenic lines compared with the WT. The PEG-simulated drought stress did not induce any significant change in the expression of fatty acid and wax biosynthesis genes in WT plants, while the expression of fatty acid and wax biosynthesis genes was significantly increased in transgenic lines compared with WT as well as unstressed transgenic control. The expression of TAG1, the gene involved in triacylglycerol (TAG) accumulation, was significantly lower in the transgenic lines than that in the WT in normal growth conditions. Drought stress slightly decreased the expression of TAG1 in the WT, but significantly lowered it in transgenic lines compared with its unstressed transgenic control and WT. Consistent with gene expression data, the cuticular wax content in Arabidopsis leaves was significantly higher in the transgenic lines than in the WT, while the oil content was not significantly different. Our results indicated that WRI3/4-like gene from Cyperus esculentus improves drought tolerance in Arabidopsis probably by promoting cuticular wax biosynthesis and, hence, could be a valuable target for improving drought tolerance in crops through recombinant DNA technology.