First Report on Resistance to HPPD Herbicides Mediated by Nontarget-Site Mechanisms in the Grass Leptochloa chinensis

• DOI: 10.1021/acs.jafc.3c04323
• Publication Date: 2023-10-27T15:17:15Z
• Authors: Boming Ju; Min Liu; Yuhang Fang; Leicheng Liu; Lang Pan
• Keywords: Herbicides; Poaceae; 4-Hydroxyphenylpyruvate Dioxygenase; Dioxygenases; Herbicide Resistance

The emergence of 4-hydroxyphenylpyruvate dioxygenase (HPPD) herbicides as efficacious target-site herbicides has been noteworthy. In recent years, only four species of broadleaf weeds have developed resistance due to the long-term widespread use of HPPD herbicides. This study represents the first reported instance of a grass weed exhibiting resistance to HPPD inhibitors. We identified a new HPPD-resistant Chinese sprangletop [Leptochloa chinensis (L.) Nees] population (R population). At the recommended dose of tripyrasulfone, the inhibition rate of the R population was only half that of the sensitive population (S). The mechanism underlying resistance does not involve target-site resistance triggered by amino acid mutations or depend on disparities within the HPPD INHIBITOR SENSITIVE 1 (HIS1) gene. The impetus for resistance appears to be interlinked with the metabolic activities of cytochrome P450 monooxygenase (P450) and glutathione S-transferase (GST) family genes. Following RNA sequencing (RNA-seq) and quantitative real-time PCR (qRT-PCR) validation, the study suggests that five P450 genes, CYP71C1, CYP74A2, CYP72A1, CYP84A1, and CYP714C2, alongside a single GST gene GSTF1, may be implicated in the process of metabolic detoxification.