Insights into the facilitation effects of putrescine in mediating the multi-pathway metabolism of bentazone to mitigate environmental risks to rice production.

BACKGROUND

Putrescine (PUT), the original by-product of polyamine biosynthesis, plays multiple roles in plant growth and defense against osmotic and environmental stresses. It may also aid in decreasing herbicide phytotoxicity, but this remains unconfirmed.

RESULTS

Compared with rice treated with 2.3 mg L-1 bentazone (BNTZ) alone, co-application of 150 mg L-1 PUT restored rice morphological performance, increasing shoot and root elongation by 7.1% and 8.3%, and elevating shoot and root dry weight by 19.4% and 22.2%, respectively. Transcriptome enrichment analysis revealed a large set of significantly up-regulated expression genes encoding herbicide detoxification enzymes, such as cytochrome P450s, acetyltransferases, methyltransferases and glycosyltransferases under BNTZ stress and these transcriptional activations were further strengthened by exogenous PUT supplementation. Relative to treatment with 1.8 mg L-1 BNTZ, exogenous PUT administration reduced BNTZ accumulation by 14.21% in roots and 23.37% in shoots. The production of key enzymes engaging in BNTZ decay was attributable to some genes showing variable expression, like acetyltransferases, cytochrome P450, glycosyltransferases, and methyltransferases. By means of liquid chromatography-quadrupole time-of-flight high-resolution tandem mass spectrometry (LC-Q-TOF-HRMS/MS), nine Phase-I transformed metabolites and 23 Phase-II conjugates were recognized within metabolic pathways, including acetylation, hydrolysis, dealkylation, glycosylation, malonylation, and methylation suggesting the involvement of multiple pathways in BNTZ-degradative metabolism.

CONCLUSION

This study proved that exogenous PUT application could enhance rice tolerance to BNTZ by activating the antioxidant systems and up-regulating Phases I, II and III detoxification enzyme genes, which reduces phytotoxicity and BNTZ bioaccumulation in rice. These findings highlight the role of PUT in facilitating BNTZ degradation and reducing its accumulation in rice and paddy fields. © 2026 Society of Chemical Industry.