Tribenuron-methyl resistance in Capsella bursa-pastoris: the co-existence of ALS target enzyme mutation (Pro-197-Ser) and overexpression of GSTF12 and ADP/ATP carrier protein.

BACKGROUND

Capsella bursa-pastoris, a prevalent wheat-field weed in China, demonstrates substantial resistance to tribenuron-methyl, a herbicide-targeting acetolactate synthase (ALS). Understanding weed herbicide-resistance mechanisms is crucial for managing resistant weed populations. However, the genes potentially involved in nontarget-site resistance (NTSR) in herbicide-resistant C. bursa-pastoris remain poorly understood and require further investigation. This research aimed to elucidate the resistance level and underlying mechanisms of a field population (R) from Shandong Province, China, to tribenuron-methyl.

RESULTS

Whole-plant bioassays revealed that the relative resistance index (RI) of the R population was 54-fold greater than that of the tribenuron-methyl-sensitive population (S). Additionally, treatment with the cytochrome P450 (CYP450) inhibitor malathion or the glutathione S-transferase (GST) inhibitor 4-Chloro-7-nitro-1,2,3-benzoxadiazole (NBD-Cl) partially mitigated the resistance of the R population to tribenuron-methyl. Sequencing of the ALS target enzyme identified a substitution of proline (CCT) at position 197 with serine (TCT). RNA sequencing combined with quantitative reverse transcription polymerase chain reaction (qRT-PCR) verification identified upregulation of a candidate GST gene (GSTF12) and an ADP/ATP carrier protein in the R population. Heterologous expression of the two candidate genes in yeast cells demonstrated enhanced growth in the presence of tribenuron-methyl.

CONCLUSION

We first identified that, in tribenuron-methyl-resistant C. bursa-pastoris, the Pro-197-Ser mutation in the ALS gene, along with GSTF12 and ADP/ATP carrier protein overexpression, jointly mediate its resistance. This enhances our understanding of herbicide-resistance mechanisms and offers a novel perspective for managing tribenuron-methyl-resistant weeds in agricultural practices. © 2025 Society of Chemical Industry.