CYP99A2 from Aegilops tauschii metabolizes pyroxsulam but not mesosulfuron-methyl, causing different natural...

Weed tolerance to herbicides poses a major threat to agricultural production. Aegilops tauschii has promising prospects for genetic development; however, the fact that this plant is invasive in China and other countries is often ignored owing to its pronounced adaptability. Among the current acetolactate synthase (ALS) inhibitors, only mesosulfuron-methyl (MM) can control A. tauschii, and pyroxsulam (P) is ineffective. However, a knowledge gap remains regarding differences in sensitivity of A. tauschii to these two ALS inhibitors.

We hypothesized that differences in sensitivity of A. tauschii to the ALS inhibitors MM and P are mediated by metabolic enzymes. Whole-plant experiments showed that the P450s inhibitor 1-Aminobenzotriazole (ABT) significantly increased the sensitivity of A. tauschii to P compared with MM. In A. tauschii, the P metabolism rate was higher than that of MMl, as detected by liquid chromatography with tandem mass spectrometry. Transcriptome sequencing and quantitative real-time polymerase chain reaction identified seven differentially expressed P450s after P and MM treatments, three of which were upregulated after P treatment and were unaffected by MM. AtCYP99A2 reduced plant sensitivity to P by metabolizing P without affecting MM by overexpressing it in Arabidopsis and inducing in vitro protein expression.

To the best of our knowledge, this is the first report on P450 involvement in A. tauschii sensitivity to two ALS-inhibitor herbicides. This study deepens current understandings of A. tauschii and facilitates subsequent screening of specific metabolic enzyme inhibitors to be used as synergists in combination with herbicides, which will provide new avenues for weed control. © 2025 Society of Chemical Industry.