稗JS12种群对噁唑酰草胺的抗性水平及机理分析

    Analysis of the resistance level and its resistant molecular mechanism of Echinochloa crus-galli population JS12 to metamifop

    • 摘要:Echinochloa crus-galli是中国水稻产区发生严重的恶性杂草之一,严重威胁水稻的产量和品质。为明确江苏省稻田稗JS12种群对噁唑酰草胺的抗性水平及抗性机理,本研究采用整株水平测定法测定了稗种群对噁唑酰草胺的敏感性;通过乙酰辅酶A羧化酶(acetyl-CoA carboxylase,ACCase)靶标基因测序和表达量测定,以及代谢酶抑制剂增效试验,阐明其产生抗性的靶标抗性机制和非靶标抗性机制;最后测定了稗JS12种群对ACCase抑制剂和其他不同作用机理除草剂的敏感性,以明确抗性种群的交互抗性和多抗性情况。结果表明:江苏省稻区稗JS12种群对噁唑酰草胺产生了13.71倍的高水平抗性;稗JS12种群ACCase基因的6个拷贝序列中均未发生氨基酸突变,药剂处理后其ACCase基因表达量显著低于敏感种群;细胞色素P450抑制剂马拉硫磷和谷胱甘肽-S-转移酶(glutathione-S-transferase,GST)抑制剂NBD-Cl均可显著提高JS12种群对噁唑酰草胺的敏感性,其鲜重抑制中量GR50由227.90 g/hm2分别降至77.51和137.93 g/hm2;抗性稗种群JS12对ACCase抑制剂氰氟草酯、精噁唑禾草灵、烯草酮和炔草酯,以及ALS抑制剂五氟磺草胺和激素类除草剂二氯喹啉酸均产生了不同程度的交互抗性和多抗性,但对新型除草剂氯氟吡啶酯和三唑磺草酮仍较为敏感。本研究表明,细胞色素P450和GST介导的代谢增强可能是稗JS12种群对除草剂产生抗性的重要原因,氯氟吡啶酯和三唑磺草酮可以用作治理该抗性种群。

       

      Abstract: Barnyardgrass (Echinochloa crus-galli) is one of the most problematic weeds infesting rice fields and causes huge crop yield losses. To clarify the resistance pattern and possible mechanisms of resistance in barnyardgrass population JS12 in Jiangsu Province, whole-plant dose-response experiments were conducted to determine the sensitivity to metamifop, and its target- and non-target-based mechanisms were clarified by gene sequencing and expression analysis of ACCase gene, as well as synergistic effects on resistance of two metabolic enzyme inhibitors. Finally, the sensitivities of JS12 population to ACCase inhibitors and other herbicides with different modes of action were analyzed to determine the cross- and multi-resistance patterns. Results showed that the JS12 population exhibited 13.71 times high-level resistance to metamifop. No amino acid substitutions conferring metamifop resistance were detected in six copies of ACCase genes in JS12 population, and the gene expression levels of ACCase were significantly lower than that of the susceptible population after herbicide treatment. Both cytochrome P450 inhibitor malathion and glutathione-S-transferase (GST) inhibitor NBD-Cl could significantly increase the susceptibility of JS12 population to metamifop, causing the GR50 (herbicide rate causing growth reduction by 50%) value to decrease from 227.90 g/hm2 to 77.51 g/hm2 and 137.93 g/hm2, respectively. In addition, the resistant population JS12 had evolved cross-resistance to ACCase inhibitors cyhalofop-butyl, fenoxaprop-p-ethyl, clethodim, and pindoxaden, and multi-resistance to acetolactate synthase (ALS)-inhibiting herbicide penoxsulam and auxin herbicide quinclorac. Nevertheless, it was still susceptible to the new herbicides florpyrauxifen-benzyl and triadimefon. This study suggested that the enhanced herbicide metabolism mediated by cytochrome P450 and GST might be an important reason for herbicide resistance in JS12 population. Florpyrauxifen-benzyl and triadimefon can be used to control the resistant population.

       

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