Iwakami Satoshi, Endo Masaki, Saika Hiroaki, Okuno Junichi, Nakamura Naoki, Yokoyama Masao, Watanabe Hiroaki, Toki Seiichi, Uchino Akira, Inamura Tatsuya
Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan (S.I., T.I.);Plant Genome Engineering Research Unit, Agrogenomics Research Center, National Institute of Agrobiological Sciences, Tsukuba 305-8602, Japan (M.E., H.S., S.T.);The Japan Association for Advancement of Phyto-Regulators, Ushiku 300-1211, Japan (J.O., N.N., M.Y.); andCrop Production Systems Division, NARO Agricultural Research Center, Tsukuba 305-8666, Japan (H.W., A.U.).
Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan (S.I., T.I.);Plant Genome Engineering Research Unit, Agrogenomics Research Center, National Institute of Agrobiological Sciences, Tsukuba 305-8602, Japan (M.E., H.S., S.T.);The Japan Association for Advancement of Phyto-Regulators, Ushiku 300-1211, Japan (J.O., N.N., M.Y.); andCrop Production Systems Division, NARO Agricultural Research Center, Tsukuba 305-8666, Japan (H.W., A.U.)
Plant Physiol. 2014 Jun;165(2):618-629. doi: 10.1104/pp.113.232843. Epub 2014 Apr 23.
Previous studies have demonstrated multiple herbicide resistance in California populations of Echinochloa phyllopogon, a noxious weed in rice (Oryza sativa) fields. It was suggested that the resistance to two classes of acetolactate synthase-inhibiting herbicides, bensulfuron-methyl (BSM) and penoxsulam (PX), may be caused by enhanced activities of herbicide-metabolizing cytochrome P450. We investigated BSM metabolism in the resistant (R) and susceptible (S) lines of E. phyllopogon, which were originally collected from different areas in California. R plants metabolized BSM through O-demethylation more rapidly than S plants. Based on available information about BSM tolerance in rice, we isolated and analyzed P450 genes of the CYP81A subfamily in E. phyllopogon. Two genes, CYP81A12 and CYP81A21, were more actively transcribed in R plants compared with S plants. Transgenic Arabidopsis (Arabidopsis thaliana) expressing either of the two genes survived in media containing BSM or PX at levels at which the wild type stopped growing. Segregation of resistances in the F2 generation from crosses of R and S plants suggested that the resistance to BSM and PX were each under the control of a single regulatory element. In F6 recombinant inbred lines, BSM and PX resistances cosegregated with increased transcript levels of CYP81A12 and CYP81A21. Heterologously produced CYP81A12 and CYP81A21 proteins in yeast (Saccharomyces cerevisiae) metabolized BSM through O-demethylation. Our results suggest that overexpression of the two P450 genes confers resistance to two classes of acetolactate synthase inhibitors to E. phyllopogon. The overexpression of the two genes could be regulated simultaneously by a single trans-acting element in the R line of E. phyllopogon.
先前的研究已证明，加利福尼亚州稻田中的有害杂草长芒稗（Echinochloa phyllopogon）种群具有多种除草剂抗性。有人提出，对两类抑制乙酰乳酸合酶的除草剂——苄嘧磺隆（BSM）和五氟磺草胺（PX）的抗性，可能是由除草剂代谢细胞色素P450活性增强所致。我们研究了最初从加利福尼亚州不同地区采集的长芒稗抗性（R）系和敏感（S）系中BSM的代谢情况。R植株通过O-去甲基化代谢BSM的速度比S植株更快。基于水稻中有关BSM耐受性的现有信息，我们分离并分析了长芒稗中CYP81A亚家族的P450基因。与S植株相比，CYP81A12和CYP81A21这两个基因在R植株中的转录更活跃。表达这两个基因之一的转基因拟南芥（Arabidopsis thaliana）能在含有BSM或PX的培养基中存活，而在这种培养基中野生型植株停止生长。R植株和S植株杂交产生的F2代抗性分离表明，对BSM和PX的抗性均受单个调控元件控制。在F6重组自交系中，BSM和PX抗性与CYP81A12和CYP81A21转录水平的升高共分离。在酵母（Saccharomyces cerevisiae）中异源产生的CYP81A12和CYP81A21蛋白通过O-去甲基化代谢BSM。我们的结果表明，这两个P450基因的过表达赋予了长芒稗对两类乙酰乳酸合酶抑制剂的抗性。这两个基因的过表达可能由长芒稗R系中的单个反式作用元件同时调控。
