Anhui Province Key Laboratory of Integrated Pest Management On Crops, School of Plant Protection, Anhui Agricultural University, Hefei, 230036, China.
College of Plant Protection, Shandong Agricultural University, Tai'an, 271018, China.
Cell Mol Life Sci. 2022 Mar 25;79(4):205. doi: 10.1007/s00018-022-04171-y.
Multiple herbicide resistance in diverse weed species endowed by enhanced herbicide detoxification or degradation is rapidly growing into a great threat to herbicide sustainability and global food safety. Although metabolic resistance is frequently documented in the economically damaging arable weed species shortawn foxtail (Alopecurus aequalis Sobol.), relevant molecular knowledge has been lacking. Previously, we identified a field population of A. aequalis (R) that had evolved metabolic resistance to the commonly used acetolactate synthase (ALS)-inhibiting herbicide mesosulfuron-methyl. RNA sequencing was used to discover potential herbicide metabolism-related genes, and four cytochrome P450s (CYP709C56, CYP71R18, CYP94C117, and CYP94E14) were identified with higher expressions in the R vs. susceptible (S) plants. Here the full-length P450 complementary DNA transcripts were each cloned with identical sequences between the S and R plants. Transgenic Arabidopsis overexpressing CYP709C56 became resistant to the sulfonylurea herbicide mesosulfuron-methyl and the triazolo-pyrimidine herbicide pyroxsulam. This resistance profile generally but does not completely in accordance with what is evident in the R A. aequalis. Transgenic lines exhibited enhanced capacity for detoxifying mesosulfuron-methyl into O-demethylated metabolite, which is in line with the detection of O-demethylated herbicide metabolite in vitro in transformed yeast. Structural modeling predicted that mesosulfuron-methyl binds to CYP709C56 involving amino acid residues Thr-328, Thr-500, Asn-129, Gln-392, Phe-238, and Phe-242 for achieving O-demethylation. Constitutive expression of CYP709C56 was highly correlated with the metabolic mesosulfuron-methyl resistance in A. aequalis. These results indicate that CYP709C56 degrades mesosulfuron-methyl and its up-regulated expression in A. aequalis confers resistance to mesosulfuron-methyl.
多种杂草物种对不同除草剂的解毒或降解能力增强而产生的抗药性，正迅速成为除草剂可持续性和全球食品安全的巨大威胁。虽然在经济上具有破坏性的耕地杂草物种节节麦（Alopecurus aequalis Sobol.）中经常记录到代谢抗性，但相关的分子知识却一直缺乏。先前，我们鉴定了节节麦（R）的一个田间种群，该种群对常用的乙酰乳酸合成酶（ALS）抑制剂除草剂甲磺隆-甲基产生了代谢抗性。使用 RNA 测序发现了潜在的除草剂代谢相关基因，并且在 R 与敏感（S）植物相比，有 4 个细胞色素 P450（CYP709C56、CYP71R18、CYP94C117 和 CYP94E14）表达更高。在此，从 S 和 R 植物中克隆了具有相同序列的全长 P450 cDNA 转录本。过表达 CYP709C56 的拟南芥转基因植株对磺酰脲类除草剂甲磺隆-甲基和三唑嘧啶类除草剂吡氟草胺具有抗性。这种抗性谱与 R 节节麦中明显的抗性谱一般相符，但不完全相符。转基因品系表现出增强的将甲磺隆-甲基解毒为 O-去甲基代谢物的能力，这与转化酵母中体外检测到的 O-去甲基除草剂代谢物相符。结构建模预测，甲磺隆-甲基与 CYP709C56 结合涉及 Thr-328、Thr-500、Asn-129、Gln-392、Phe-238 和 Phe-242 等氨基酸残基，以实现 O-去甲基化。CYP709C56 的组成型表达与节节麦中甲磺隆-甲基的代谢抗性高度相关。这些结果表明，CYP709C56 降解甲磺隆-甲基，其在节节麦中的上调表达赋予对甲磺隆-甲基的抗性。
