An ABCG-type transporter endows fomesafen resistance in Amaranthus retroflexus L

Amaranthus retroflexus L. is one of the most damaging and noxious weeds in Chinese soybean fields and poses a serious threat to soybean production. Currently, the protoporphyrinogen oxidase-inhibiting herbicide fomesafen is key in controlling A. retroflexus in soybean fields. However, an increasing number of cases of fomesafen resistance in A. retroflexus have been reported across multiple regions, presenting challenges in weed management. In this study, we investigated a fomesafen-resistant A. retroflexus population that evolved in Heilongjiang Province, China, and discovered an ATP-binding cassette transporter (ArABCG5) that is significantly upregulated in the fomesafen-resistant A. retroflexus population. Overexpression of ArABCG5 in Arabidopsis thaliana conferred herbicide resistance. Virus-induced gene silencing experiments further demonstrated that silencing ArABCG5 reduced A. retroflexus's resistance to fomesafen. Additionally, subcellular localization analysis, structural modeling, and molecular docking results suggested that this transporter protein likely localizes to the plasma membrane and may facilitate the movement of fomesafen into the apoplast.