Glycosyltransferase genes are associated with resistance to cyhalofop-butyl in a Chinese Echinochloa crus-galli population.

Abstract

Echinochloa crus-galli is the most troublesome and widespread weed of most rice-growing regions of the world. Cyhalofop-butyl, a herbicide within the acetyl-CoA carboxylase (ACCase) chemical group, has been extensively used to control barnyardgrass in rice. The repeated exposure to cyhalofop-butyl has led to resistance evolution in E. crus-galli populations. In this study, we identified a population of E. crus-galli (R-HN) in a rice field in Hunan, China, that developed resistance to cyhalofop-butyl at 4.49-fold the recommended field dose. No known target mutation was detected in the ACCase gene of the R-HN population by ACCase sequencing compared to sensitive populations. Both cytochrome P450 (CYP450) and glutathione S-transferase (GST) inhibitors could not significantly reverse the resistance to cyhalofop-butyl. The nontarget-site resistance (NTSR) mechanism was investigated by transcriptome sequencing. Validation of the screened candidate genes by quantitative real-time (qRT)-PCR revealed that six glycosyltransferases (GTs) and four ATP-binding cassette (ABC) transporter genes were consistently upregulated in the R-HN population. Five GTs and one ABC transporter genes were constitutively upregulated after cyhalofop-butyl treatment in the R-HN population. Molecular docking results showed that the significant binding energy of GT79, GT75L6 and GT74E among all candidate genes. Thus, the GT genes appear to be directly implicated in NTSR to cyhalofop-butyl in the R-HN populations through metabolic enhancement, but their functional characterization needs to be studied. © 2024 Society of Chemical Industry.