河南省部分地区麦田荠菜对苯磺隆的抗性水平及抗性靶标分子机制
Resistance of Capsella bursa-pastoris to tribenuron-methyl in winter wheat fields in some areas of Henan Province and its molecular mechanism

为明确河南省部分地区麦田荠菜Capsella bursa-pastoris对苯磺隆的抗性水平及抗性靶标分子机制，采用整株生物法测定了12个荠菜种群的抗性水平，并对乙酰乳酸合成酶（acetolactate synthase，ALS）离体活性和ALS基因突变进行了测定分析。结果表明，商丘市民权县花园村（MQ）、周口市西华县小于楼村（XH）、平顶山市叶县穆寨村（YX）、许昌市长葛市董庄村（CG）采集的荠菜种群对苯磺隆产生了较高的抗性，GR50分别为129.14、110.67、62.91和85.29 g/hm2，抗性倍数分别为215.23、184.45、104.85和142.15倍；ALS离体活性测定所得I50分别为5.85、4.87、1.38和3.83 μmol/L，抗性倍数分别为83.57、69.57、19.71和54.71倍；其余8个种群的GR50在0.60~2.86 g/hm2之间，抗性倍数在1.00~4.77之间；I50在0.07~0.37 μmol/L之间，抗性倍数在1.00~5.29之间。荠菜种群MQ、XH的ALS基因Domain A区域第197位脯氨酸（CCT）均突变为丝氨酸（TCT），荠菜种群CG的第197位脯氨酸（CCT）突变为亮氨酸（CTT），表明靶标ALS基因突变是荠菜对苯磺隆产生抗性的重要原因之一，但荠菜种群YX的ALS基因保守区内暂未发现突变位点，其抗药性可能由其它原因造成。
To investigate the resistance levels of Capsella bursa-pastoris to tribenuron-methyl in winter wheat fields in some areas of Henan Province and its molecular mechanism,12 C.bursa-pastoris populations were assessed with three methods:whole-plant bioassay,acetolactate synthase (ALS) activity in vitro assay and analysis of ALS mutation.The results showed that C.bursa-pastoris populations from Huayuan Village,Minquan County in Shangqiu City,Xiaoyulou Village,Xihua County in Zhoukou City,Muzhai Village,Ye County in Pingdingshan City and Dongzhuang Village,Changge City in Xuchang City had higher level of resistance than other populations.The GR50 values determined with the method of whole-plant bioassay were 129.14,110.67,62.91 and 85.29 g/hm2,respectively,and the corresponding relative resistance indexes were 215.23,184.45,104.85 and 142.15,respectively.The I50 values determined with in vitro assay of ALS activity were 5.85,4.87,1.38 and 3.83 μmol/L,respectively,and the corresponding relative resistance indexes were 83.57,69.57,19.71 and 54.71,respectively.The GR50 of other eight populations ranged from 0.60 g/hm2 to 2.86 g/hm2,and the corresponding resistance indexes ranged from 1.00 to 4.77;the I50 values were in the range of 0.07-0.37 μmol/L and the calculated resistance indexes in the range of 1.00-5.29.ALS sequence analysis indicated that proline (CCT) at position 197 in Domain A of the ALS gene was substituted by serine (TCT) in the populations MQ and XH,and leucine (CTT) in the population CG.The Pro197 mutation in ALS could be one of important reasons for the observed high resistance to tribenuron-methyl.In contrast,no point mutations were indentified in the ALS gene from the population YX,indicating other mechanisms might be responsible for its resistance.