Department of Environment, College of Environment and Resources, Xiangtan University, Xiangtan 411105, China.
College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China.
Environ Sci Technol. 2023 Mar 28;57(12):4852-4862. doi: 10.1021/acs.est.2c09352. Epub 2023 Mar 16.
Inappropriate application of pesticides not only causes sub-lethal effects on ecosystem service providers but also reduces crop yield and quality. As a xenobiotic signal molecule, pesticides may interact with signal transduction receptors in crops, resulting in oxidative damage and even metabolic perturbations. We discovered that three neonicotinoid insecticides (NIs), namely, imidacloprid, thiamethoxam, and clothianidin, at 0.06-0.12 kg ai/ha significantly inhibited the auxin signal pathway in rice leaves, thereby reducing the intracellular auxin (IAA) content. Molecular simulation further confirmed that NIs occupied the binding site where auxin transporter-like proteins 1 (LAX11) and 2 (LAX12), in which Thr253 and Asn66 of LAX11, as well as Thr244 and Asn57 of LAX12, were bound to the nitroguanidine of NIs via H-bonds. Meanwhile, Asn66 of LAX11 and Asn57 of LAX12 interacted with nitroguanidine via aromatic H-bonds. Moreover, phenylpropanoid biosynthesis was significantly disturbed because of the inhibited auxin signal pathway. Notably, peroxidase-coding genes were downregulated with a maximum value greater than 10-fold, resulting in decreased antioxidant metabolites flavone (37.82%) and lignin content (20.15%). Ultimately, rice biomass was reduced by up to 25.41% due to the decline in IAA content and antioxidant capacity. This study deeply explored the molecular mechanism of metabolic perturbations in crops stressed by pesticides, thus providing a scientific basis for pesticide environmental risk assessment and agricultural product safety.
不合理使用农药不仅会对生态系统服务提供者造成亚致死效应，还会降低作物的产量和质量。作为一种外源性信号分子，农药可能与作物中的信号转导受体相互作用，导致氧化损伤，甚至代谢紊乱。我们发现，三种新烟碱类杀虫剂（NIs），即吡虫啉、噻虫嗪和噻虫胺，在 0.06-0.12 kg ai/ha 显著抑制了水稻叶片中的生长素信号通路，从而降低了细胞内生长素（IAA）的含量。分子模拟进一步证实，NIs 占据了生长素转运蛋白 1（LAX11）和 2（LAX12）的结合位点，其中 LAX11 的 Thr253 和 Asn66 以及 LAX12 的 Thr244 和 Asn57 通过氢键与 NIs 的硝胍基团结合。同时，LAX11 的 Asn66 和 LAX12 的 Asn57 通过芳族氢键与硝胍相互作用。此外，由于生长素信号通路受阻，苯丙烷生物合成受到显著干扰。值得注意的是，过氧化物酶编码基因被下调，最大下调值大于 10 倍，导致抗氧化代谢物黄酮（37.82%）和木质素含量（20.15%）减少。最终，由于 IAA 含量和抗氧化能力下降，水稻生物量减少了 25.41%。本研究深入探讨了农药胁迫下作物代谢紊乱的分子机制，为农药环境风险评估和农产品安全提供了科学依据。
