Glutathione S-transferase genes PfGSTU6 and PfGSTL1 involved in mesosulfuron-methyl resistance in Polypogon fugax.
TL;DR
The cross-resistance profile of the resistant P. fugax population is characterized, which provides guidance for developing targeted field weed resistance management strategies and provides genetic resources for resistance monitoring and crop breeding.
Abstract
Background
Polypogon fugax is a major weed in wheat and winter canola fields in China. Two populations, SD-4 and JS-13, showing resistance to the ALS inhibitor mesosulfuron-methyl, were collected from winter wheat fields. This study aimed to characterize their resistance level and cross-resistance profile, investigate the resistance mechanism and identify its functional genes.
Results
Dose-response assays showed that SD-4 and JS-13 have high-level resistance to mesosulfuron-methyl (15.9-and 16.4-fold, respectively) and cross-resistance to the ACCase inhibitors clodinafop-propargyl, fenoxaprop-P-ethyl, quizalofop-p-ethyl, and the PDS inhibitor diflufenican. Sequencing of the ALS gene revealed no known target-site mutations within the eight conserved resistance-associated regions. Pre-treatment with the cytochrome P450 monooxygenase (P450) inhibitor malathion or the glutathione S-transferase (GST) inhibitor NBD-Cl increased herbicide sensitivity in resistant plants. The resistant plants showed higher inducible GST activity. Herbicide residues analysis observed that resistant plants exhibiting increased mesosulfuron-methyl metabolism, and the enhanced metabolism could be reduced by both inhibitors. Integrated transcriptomic and qRT-PCR analysis identified 17 stably upregulated genes, including PfGSTU6 and PfGSTL1. Escherichia coli and rice callus overexpressing PfGSTU6 and PfGSTL1 exhibit significantly enhanced herbicide tolerance to mesosulfuron-methyl, and molecular docking analysis confirmed the strong binding affinity of GST proteins to the target herbicide.
Conclusions
The P450s and GSTs mediated herbicide metabolism confer mesosulfuron-methyl resistance in P. fugax. This study elucidates the resistance mechanism and provides genetic resources for resistance monitoring and crop breeding. In addition, we characterized the cross-resistance profile of the resistant P. fugax population, which provides guidance for developing targeted field weed resistance management strategies. © 2026 Society of Chemical Industry.