Pyroxasulfone tolerance in wheat: Role of enhanced herbicide metabolism and coexpression of key metabolic genes

Abstract

Pyroxasulfone has been widely used to control malignant weeds in wheat fields. However, differences in pyroxasulfone tolerance across wheat varieties warrant attention owing to their potential impact on food production security. In this study, 54 wheat varieties were collected for screening, and Yunong 922 with 6.01-fold higher tolerance than Zhengmai 1354 was identified. Ultra-performance liquid chromatography–mass spectrometry analysis revealed that Yunong 922 exhibited a significantly shorter degradation half-life of pyroxasulfone (5.03 days) than Zhengmai 1354 (7.02 days). The P450 inhibitor malathion and the glutathione S-transferase (GST) inhibitor NBD-Cl reduced the tolerance factor of Yunong 922 to pyroxasulfone from 6.01 to 1.44 and 1.16, respectively, with no significant difference in tolerance to pyroxasulfone compared with Zhengmai 1354. RNA-Seq transcriptome analysis was used to identify candidate genes that may confer metabolic tolerance to pyroxasulfone in wheat. Eight candidate genes (five P450 enzymes and three GSTs) exhibited significantly different expression levels between Yunong 922 and Zhengmai 1354, as validated by qRT–PCR. Pyroxasulfone tolerance in Yunong 922 is associated with the coordinated upregulation of CYP72A397, CYP72A14, and GSTDHAR1, each contributing approximately 33.7 %, 32.6 %, and 33.7 % to the dominant principal component 1 that accounts for 88.7 % of the explained variance. These results revealed that the faster degradation of pyroxasulfone observed in Yunong 922 could be linked to the higher expression of P450s and GSTs, though this relationship remains to be confirmed. This study also offers valuable insights into mechanisms underlying crop tolerance and informs the development of herbicide management strategies.