Comprehensive analyses of the effects of exogenous α ‐ tocopherol on mediating multiphase metabolism of anilofos and mitigating environmental risks in rice production

BACKGROUND: As a pivotal member of the tocochromanol family, α-tocopherol (α-TOC) plays a key role in eliminating reactive oxygen species produced during photosynthesis and may contribute to metabolism and stress responses in plants, such as helping to reduce pesticide phytotoxicity. However, its role in modulating pesticide metabolism in crops remains unclear. RESULTS: In this study, we examined the physiological responses of rice (Oryza sativa) to six doses of anilofos (0-0.08 mg/L) and two concentrations of α-TOC (0 and 250 mg/L). Compared with rice treated solely with 0.08 mg/L anilofos, co-treatment with 250 mg/L α-TOC restored rice morphological performance, increasing root elongation by 6.8% and shoot length by 41.8%; Meanwhile, the dry weight of root and shoot rose by 8.2% and 20.7%, respectively. In addition, six rice root and shoot libraries were created and treated with either anilofos or anilofos + α-TOC. Then, the biochemical and catalytic mechanisms underlying anilofos-triggered decomposition in rice were examined via RNA-sequencing and liquid chromatography coupled to quadrupole time-of-flight high-resolution tandem mass spectrometry (LC-Q-TOF-HRMS/MS). Transcriptome enrichment analysis revealed a large set of significantly up-regulated expression genes encoding xenobiotic detoxification and pesticide catabolic enzymes, such as cytochrome P450s, glycosyltransferases (GTs) and ATP-binding cassette (ABC) transporters under anilofos stress and these transcriptional activations were further strengthened by exogenous α-TOC supplementation. As compared to treatment with 0.08 mg/L anilofos only, the addition of exogenous α-TOC reduced anilofos accumulation by 19.3% in roots and 11.8% in shoots, respectively. The synthesis of key enzymes involved in anilofos decomposition has been connected with a number of genes exhibiting variable expression levels, like acetyltransferases, cytochrome P450s, methyltransferases, GTs, and ABC transporters. LC-Q-TOF-HRMS/MS identified six metabolites and 12 conjugates involving acetylation, hydrolysis, glycosylation, methylation, and interaction with amino acids, aimed at improving anilofos-degradative metabolism. CONCLUSION: These results suggest that external α-TOC treatment enhances rice tolerance to anilofos by activating the antioxidant system and up-regulating Phases I, II and III detoxification enzyme genes, which reduces reactive oxygen species burst and anilofos bioaccumulation in rice. These findings highlight the role of α-TOC in promoting anilofos degradation and reducing its accumulation in rice and paddy fields.