Overexpression of the cytochrome P450 gene CYP99A3 likely mediates mesosulfuron-methyl resistance in Lolium multiflorum from China.

Authors

Pei Zhang, Yuqing Liu, Xueliang Tian, Hongliang Wang, Runqiang Liu, Guochang Wang, Yanbing Wu

Published in

Pesticide biochemistry and physiology. Volume 223. Pages 107300. Epub Aug 09, 2026.

Abstract

Lolium multiflorum L. (Italian ryegrass) is a noxious weed causing severe yield losses in wheat production globally, and its rapid expansion across major wheat-producing regions in China poses an escalating agricultural threat. Recently, field-recommended doses of the acetolactate synthase (ALS) inhibitor mesosulfuron-methyl have failed to effectively control certain L. multiflorum populations. This study evaluated the resistance level and elucidated the underlying mechanisms in a suspected mesosulfuron-methyl-resistant L. multiflorum population (ZMHF-R) collected from China. Whole-plant bioassays demonstrated that the ZMHF-R population exhibited a high level of resistance (43.34-fold) to mesosulfuron-methyl. Replicate sequencing of the ALS gene revealed no known target-site mutations, thereby excluding target-site mutation-mediated resistance. Pretreatment with the cytochrome P450 inhibitors piperonyl butoxide (PBO) and malathion significantly synergized mesosulfuron-methyl toxicity in ZMHF-R, implicating P450 monooxygenases in the resistance phenotype. Comparative RNA-seq and RT-qPCR validation identified the constitutive overexpression of a specific P450 gene, LmCYP99A3, in the R population. Molecular docking simulations predicted favorable binding and potential metabolic activity of the LmCYP99A3 protein toward mesosulfuron-methyl. Furthermore, transgenic rice calli heterologously overexpressing LmCYP99A3 exhibited a distinct resistance phenotype against the herbicide. Taken together, this study functionally validates that LmCYP99A3 mediates mesosulfuron-methyl resistance in L. multiflorum, expanding our understanding of the metabolic basis of NTSR in this global weed species.

PMID:
42697669
Bibliographic data and abstract were imported from PubMed on 05 Sep 2026.

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