玉米田反枝苋对烟嘧磺隆的抗性水平及靶标抗性分子机理

Resistance level and target-resistance molecular mechanism to nicosulfuron in Amaranthus retroflexus

为明确玉米田主要杂草反枝苋对烟嘧磺隆的抗性水平及靶标抗性分子机理,采用整株水平测定法检测了黑龙江省玉米田反枝苋对烟嘧磺隆的抗性水平,通过靶标酶离体活性测定,分析了抗性和敏感种群反枝苋乙酰乳酸合成酶（ALS）对烟嘧磺隆的敏感性,并通过靶标ALS基因克隆测序进行了序列比对分析。结果显示：黑龙江省反枝苋疑似抗性种群（HLJ-R）对烟嘧磺隆已产生较高水平抗性,其抗性倍数达13.7;酶活性测定结果表明：烟嘧磺隆对HLJR种群ALS活性的抑制中浓度（IC50）值是对敏感种群（TA-S） IC50值的43.9倍;与TA-S种群相比,HLJ-R种群ALS基因205位丙氨酸突变为缬氨酸,574位色氨酸突变为亮氨酸。研究表明,黑龙江省玉米田反枝苋对烟嘧磺隆已产生较高水平抗性,且靶标ALS基因的突变可能是其抗性产生的主要原因之一。

To investigate the molecular basis of resistance to nicosulfuron in Amaranthus retroflexus L.,the whole-plant dose-response assays were conducted to determine the level of resistance. And the in vitro acetolactate synthase（ALS） inhibition assay and ALS gene sequence analysis were conducted to clarify the target-site based resistance mechanism. Results of whole-plant dose-response experiments showed that the resistant population（HLJ-R） had evolved high-level（13.7-fold） of resistance to nicosulfuron. The in vitro ALS activity assay showed that the IC50 value of nicosulfuron in the resistant population（HLJ-R） was 43.9-folds higher than that of the sensitive population（TA-S）. The ALS gene sequence analysis showed that two ALS resistance mutation occurred in the resistant plants, including the alanine acid（Ala） at the position 205 substituted by valine acid（Val）, and tryptophan acid（Trp） at the position 574 substituted by leucine acid（Leu）. These findings indicated that the reduced ALS sensitivity to nicosulfuron resulted from Ala-205-Val and Trp-574-Leu, which was the molecular basis for the target-site based resistance to nicosulfuron in A. retroflexus.