Enhanced MATE transporter DTX6/PQT15 confers paraquat resistance

Paraquat is one of the most widely used non-selective herbicides and has elicited the emergence of paraquat resistant weeds. However, the molecular mechanisms of paraquat resistance are not completely understood. Here we report an Arabidopsis gain-of-function mutant pqt15-D with significantly enhanced resistance to paraquat and the corresponding PQT15 encoding the MATE transporter DTX6. A point mutation at +932 bp in DTX6 causing the G311E amino acid residue change brings about the enhanced paraquat resistance of pqt15-D. Overexpression of DTX6/PQT15 in the wild type also confers strong paraquat resistance, whereas the DTX6/PQT15 knockout mutants exhibits hypersensitive phenotype to paraquat. Moreover, heterologous expression of DTX6 and DTX6-D in E. coli significantly enhances bacterial resistance to paraquat. DTX6/PQT15 mainly localizes in the plasma membrane as shown by DTX6-GFP and functions as a paraquat efflux transporter as demonstrated by paraquat efflux assays with isolated protoplasts and bacterial cells. Taken together, our results demonstrate that DTX6/PQT15 is an efflux transporter and confers paraquat resistance by exporting paraquat out of cytosol, therefore unraveling a molecular mechanism of paraquat resistance in higher plants and providing a promising candidate of generating paraquat resistance crops.