Pyroxsulam Boosts Wheat Tolerance to Bixlozone: Effects and Mechanisms

Bixlozone has significant potential as a pre-emergence and early post-emergence herbicide in wheat production across China. However, its safety when applied to wheat is poor, frequently causing phytotoxicity. This study confirmed the capacity of pyroxsulam to mitigate bixlozone-induced injury without compromising weed control efficacy and examined the underlying processes. Wheat exposed to bixlozone alone developed pronounced chlorosis and significant reductions in tiller formation, ultimately lowering the grain yield. In contrast, co-treatment with pyroxsulam substantially relieved chlorosis and restored both the tiller number and yield performance. Bixlozone reduced chlorophyll and carotenoid levels, impairing the function of photosystem II (PSII), which was mitigated by pyroxsulam application. Transcriptome profiling showed that pyroxsulam strongly activated detoxification-related pathways, especially those associated with glutathione S-transferases (GSTs) and ATP-binding cassette (ABC) transporters, which facilitate the metabolic detoxification or compartmentalization of bixlozone. qRT-PCR further validated the marked induction of key detoxification genes ABCC8-X1, GSTU6 and ABCC10 following pyroxsulam addition. Collectively, this study provides initial mechanistic insight into how pyroxsulam, though itself a herbicide, can enhance wheat tolerance to bixlozone by stimulating endogenous detoxification systems. These findings offer a framework for the development of safer herbicide mixtures and expand current understanding of crop–herbicide interactions, providing meaningful implications for herbicide management and sustainable agricultural systems.