荠菜对乙酰乳酸合成酶抑制剂类除草剂的抗性水平及其分子机制

为明确荠菜种群对苯磺隆的抗性水平及其靶标抗性产生的分子机制，采用整株水平测定法测定了荠菜对苯磺隆及其他5种乙酰乳酸合成酶（ALS）抑制剂类除草剂的抗性水平，同时扩增和比对了荠菜抗性和敏感种群之间ALS基因的差异。结果显示:与敏感种群15-ZMD-1相比，抗性种群15-ZMD-5对苯磺隆产生了高水平抗性，抗性倍数为219.6；15-ZMD-5种群不同单株中共存在3种突变方式，分别为ALS基因197位点脯氨酸（CCT）突变为亮氨酸（CTT）、574位点色氨酸（TGG）突变为亮氨酸（TTG）以及单株同时发生上述197和574位点的氨基酸突变。15-ZMD-5抗苯磺隆种群对嘧草硫醚、啶磺草胺和氟唑磺隆均产生了高水平的交互抗性，抗性倍数分别为41.2、79.3和87.8；对双氟磺草胺和咪唑乙烟酸产生了低水平的交互抗性，抗性倍数分别为8.5和5.6。分析表明，荠菜抗性种群ALS基因发生的氨基酸突变可能是导致其对ALS抑制剂类除草剂产生抗性的重要原因之一。

Resistance to acetolactate synthase-inhibiting herbicides in Capsella bursa-pastoris and its molecular resistance mechanism

Whole-plant dose-response experiments were conducted to investigate the resistance levels to tribenuron-methyl and other five kinds of acetolactate synthase (ALS)-inhibiting herbicides of Capsella bursa-pastoris population. To identify its molecular resistance mechanism, ALS gene fragments were amplified, sequenced and compared with the susceptible population. The results showed that the resistant population 15-ZMD-5 had evolved high-level resistance to tribenuron-methyl compared with the susceptible population 15-ZMD-1, and the resistance index was 219.6. There were three different kinds of mutation at ALS sequence in the resistant population:CCT (Pro)-197-CTT (Leu), TGG (Trp)-574-TTG (Leu), and all of the mutations occur at the same time. The tribenuron-methyl-resistant 15-ZMD-5 population showed high-level cross-resistance to pyrithiobac sodium, pyroxsulam and flucarbazone-Na, with resistance index of 41.2, 79.3 and 87.8, respectively, and low-level crossresistance to florasulam and imazethapyr with resistance index of 8.5 and 5.6, respectively. This study demonstrated that the mutation in the ALS gene was one of main reasons for the resistance to LSinhibiting herbicides in shepherd''s purse populations.