宁夏地区稗草种群对五氟磺草胺的抗性机制研究

Resistance mechanism of Echinochloa crus-galli to penoxsulam in the rice field in Ningxia province

为了明确宁夏稻区稗草对五氟磺草胺抗性水平及抗性机制。采用整株生物测定法测定了宁夏地区6个稗的原变种Echinochloa crus-galli var.crus-galli种群对五氟磺草胺的抗性水平,并测定了每个种群的乙酰乳酸合酶基因(ALS)序列和ALS酶离体活性,以及P450抑制剂马拉硫磷对稗草种群抗性水平的影响。结果显示,与敏感种群相比,5个疑似抗性种群对五氟磺草胺表现出不同程度的抗性(10.18倍~32.71倍),其中抗性种群N14,N22,N27和N51的ALS 574位色氨酸突变为亮氨酸,N53的197位脯氨酸突变为亮氨酸,敏感种群N43没有发现突变位点,五氟磺草胺对抗性种群ALS酶的IC_(50)均明显高于敏感种群,马拉硫磷对五氟磺草胺有增效作用,可提高稗草种群对五氟磺草胺的敏感性。综上所述,稗草种群对五氟磺草胺产生抗性是由于靶标基因ALS突变,同时稗草种群对五氟磺草胺的抗性也可能与细胞色素P450介导的代谢增强有关。

In order to determine the resistance level and mechanism of Echinochloa crus-galli var.crus-galli to penoxsulam in Ningxia province,we detected the resistance levels of six populations to penoxsulam by whole-plant pot experiments.The sequence of acetolactate synthase gene and the activity of ALS were also detected in vitro.We investigated the effect of malathion,a P450 inhibitor,on the resistance level of these populations to penoxsulam.Five populations showed various resistance levels to penoxsulam(10.18-fold to 32.71-fold).The resistant populations N14,N22,N27 and N51 had mutations at the position 574 of ALS(W574L),and N53 had mutation at position 197(P197L).No mutation was found in the sensitive population N43.The IC_(50) values of penoxsulam to ALS from the resistant populations were obviously higher than that from the sensitive population.Malathion had synergistic effects on penoxsulam,which could increase the sensitivity of the resistant populations to penoxsulam.Thus,the resistance of E.crus-galli populations to penoxsulam was caused by the target-site mutation of ALS gene.Meanwhile,the resistance might be related to the enhanced metabolism mediated by cytochrome P450.