MOE Key Laboratory of Environmental Remediation & Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
College of Science and Technology, Ningbo University, Ningbo 315211, China.
J Agric Food Chem. 2022 May 11;70(18):5516-5525. doi: 10.1021/acs.jafc.1c07727. Epub 2022 Apr 27.
The responses of trace elements and secondary metabolites to stress can reflect plant adaptation to the environment. If and how the imperative trace element Fe and the defensive secondary metabolite 2,4-dihydroxy-7-methoxy-2-1,4-benzoxazine-3(4)-one (DIMBOA) mediate the toxicity of chiral herbicides to nontarget plants remains inconclusive. We found that the herbicidal-active imazethapyr enantiomer [()-IM] stimulated heme oxygenase-1 activity, triggered the release of the catalytic product Fe, increased reactive oxygen species production, decreased the DIMBOA content, and increased the DIMBOA-Fe content. XAFS analyses and Fenton assays demonstrated that DIMBOA could relieve phytotoxicity by chelating excessive Fe to restore Fe homeostasis. The free radical scavenging ability of the chelate of DIMBOA and Fe was also involved. This work refines the dual role of DIMBOA and Fe in mediating the enantioselective phytotoxicity of chiral herbicides, which provides a new direction for improving the herbicide resistance of crops.
微量元素和次生代谢物对胁迫的响应可以反映植物对环境的适应。必需微量元素 Fe 和防御性次生代谢物 2,4-二羟基-7-甲氧基-2-[1,4]苯并恶嗪-3(4)-酮（DIMBOA）如何以及是否介导手性除草剂对非靶标植物的毒性尚不清楚。我们发现，具有除草活性的咪唑乙烟酸对映体[()-IM] 刺激血红素加氧酶-1 活性，引发催化产物 Fe 的释放，增加活性氧的产生，降低 DIMBOA 含量，增加 DIMBOA-Fe 含量。XAFS 分析和 Fenton 测定表明，DIMBOA 通过螯合过量的 Fe 来缓解植物毒性，以恢复 Fe 平衡。铁与 DIMBOA 形成的螯合物的自由基清除能力也与之相关。这项工作细化了 DIMBOA 和 Fe 在介导手性除草剂对映选择性植物毒性中的双重作用，为提高作物的除草剂抗性提供了新的方向。
