Kuk Yong In, Jung Ha Il, Kwon Oh Do, Lee Do Jin, Burgos Nilda R, Guh Ja Ock
Biotechnology Research Institute, Chonnam National University, Gwangju 500-757, Korea.
Pest Manag Sci. 2003 Sep;59(9):949-61. doi: 10.1002/ps.722.
Nine Monochoria vaginalis Pres1 accessions from Chonnam province, Korea were tested for resistance to the sulfonylurea herbicide, imazosulfuron, in whole-plant response bioassay. All accessions were confirmed resistant (R) to imazosulfuron. The GR50 (imazosulfuron concentration that reduced shoot dry weight by 50%) values of R accessions were 1112-3172 (accession #9) times higher than that of the standard susceptible (S) accession. Accession #9 exhibited cross-resistance to other sulfonylurea herbicides, bensulfuron-methyl, cyclosulfamuron and pyrazosulfuron-ethyl, but not to the imidazolinone herbicides, imazapyr and imazaquin. The R biotype could be controlled by other herbicides with different modes of action, such as mefenacet and pyrazolate, applied to soil at recommended rates. Foliar-applied herbicides, 2,4-D and bentazone, also controlled both the R and S biotypes. Sulfonylurea-based mixtures, except ethoxysulfuron plus fentrazamide, did not control resistant M. vaginalis. Rice yield was reduced 70% by resistant M. vaginalis that escaped pyrazosulfuron-ethyl plus molinate, compared with hand weeding in direct-seeded rice culture. In contrast, rice yield was reduced 44% by resistant M. vaginalis that survived the pyrazosulfuron-ethyl plus molinate treatment, compared with pyrazolate plus butachlor in transplanted rice culture. In vitro acetolactate synthase (ALS) activity of the R biotype was 183, 35, 130 and 31 times more resistant to imazosulfuron, bensulfuron-methyl, cyclosulfamuron and pyrazosulfuron-ethyl, respectively, than the S biotype. Imidazolinone herbicides, imazapyr and imazaquin had similar effect on in vitro ALS activity of the R and S biotypes. The in vivo ALS activity of the R biotype was also less affected than the S biotype by the sulfonylurea herbicides imazosulfuron and pyrazosulfuron-ethyl. Results of in vitro and in vivo ALS assays indicate that the resistance mechanism of M. vaginalis to sulfonylurea herbicides may be due, in part, to an alteration in the target enzyme, ALS. Since the level of resistance in the enzyme assay was much lower than that in the whole-plant assay, other mechanisms of resistance, such as herbicide metabolism, may be involved.
对来自韩国全罗南道的9个雨久花（Monochoria vaginalis Presl）种质进行了磺酰脲类除草剂咪唑磺隆的整株抗性生物测定。所有种质均被确认为对咪唑磺隆具有抗性（R）。抗性种质的GR50（使地上部干重降低50%的咪唑磺隆浓度）值比标准敏感（S）种质高1112 - 3172倍（种质编号9）。种质编号9对其他磺酰脲类除草剂苄嘧磺隆、环丙嘧磺隆和吡嘧磺隆表现出交叉抗性，但对咪唑啉酮类除草剂咪草烟和咪唑喹啉酸不具有交叉抗性。抗性生物型可以通过以推荐剂量施用于土壤中的其他具有不同作用方式的除草剂来控制；例如苯噻酰草胺和吡唑特。叶面喷施的除草剂2,甲4氯和灭草松也能控制抗性和敏感生物型。除乙氧嘧磺隆加嗪草酸酰胺外，基于磺酰脲的混剂不能防除抗性雨久花。在直播水稻栽培中，与人工除草相比，逃避了吡嘧磺隆加杀草丹处理的抗性雨久花使水稻产量降低了70%。相比之下，在移栽水稻栽培中，与吡唑特加丁草胺相比，在吡嘧磺隆加杀草丹处理中存活下来的抗性雨久花使水稻产量降低了44%。抗性生物型的体外乙酰乳酸合成酶（ALS）活性对咪唑磺隆、苄嘧磺隆、环丙嘧磺隆和吡嘧磺隆的抗性分别比对敏感生物型高183、35、130和31倍。咪唑啉酮类除草剂咪草烟和咪唑喹啉酸对抗性和敏感生物型的体外ALS活性具有相似的影响。磺酰脲类除草剂咪唑磺隆和吡嘧磺隆对抗性生物型体内ALS活性的影响也小于对敏感生物型的影响。体外和体内ALS测定结果表明，雨久花对磺酰脲类除草剂的抗性机制可能部分归因于靶标酶ALS的改变。由于酶测定中的抗性水平远低于整株测定中的抗性水平，可能涉及其他抗性机制，如除草剂代谢。
