菵草对ACCase抑制剂和ALS抑制剂的抗性机理研究

Due to much more demand for foods and high cost for labors, the chemical herbicides as the effective way to control weeds are applied increasingly, which has resulted in evolved resistance in key weeds infesting cropping systems worldwide. American sloughgrass (Beckmannia syzigachne) is one of the most common infested monocotyl weed species in rice-wheat and canola zones in China with populations that have evolved resistance to ACCase-inhibiting and ALS herbicides being the main two family herbicides in practice. It is very difficult to control this resistant weed which could reduce the yield of crops significantly. The American Sloughgrass (Beckmannia syzigachne) populations which are resistant to ACCase-inhibiting and ALS-inhibiting herbicides are used to detect the target enzymes, the ACCase and ALS. The bioactivities of ACCase and ALS, the mutation points of the resistant populations, the relation of the different chromosome ploidy with their resistant levels, are conducted to confirm the resistant mechanisms by the classical physical and chemical method and molecular method. The dispersal risk of resistant genes is also evaluated by the natural crossing between the resistant weed and susceptible weed. The research will be helpful to control and management of the complicate weedy resistances.

随着全球粮食需求增加，劳动力资源短缺，化学除草剂被广泛大量应用，农田杂草抗药性问题越来越突出，杂草抗药性机理及治理研究已成为全球研究的热点和难点问题。近年来我国长江流域稻茬麦和油菜田广泛危害的菵草对乙酰辅酶A羧化酶（ACCase）抑制剂和乙酰乳酸合成酶（ALS）抑制剂产生了抗性，菵草对这两类主打除草剂品种的抗性的发生，给菵草化学防除带来了极大的困难。本项目以对ACCase抑制剂和ALS抑制剂产生抗性的菵草为研究对象，针对靶标酶ACCase和ALS，采用生理生化和分子生物学手段，研究靶标酶活性、靶标酶突变位点、突变类型及染色体倍性差异与抗药性的关系，从而明确菵草对上述两类除草剂产生抗性的分子基础，并通过研究抗药性菵草个体间的自然杂交情况，明确菵草多抗性发生的风险和可能的一个途径，为日益复杂的抗药性菵草的有效治理提供科学依据。

菵草Beckmannia syzigachne (Steud.) Fern.是禾本科一年生或越年生杂草，主要危害我国长江中下游小麦和油菜田。ACCase抑制剂和ALS抑制剂类除草剂是其主要防除药剂，但这两类药剂长期使用后，抗药性问题非常突出，甚至有多抗性种群出现。本项目分析了采自安徽、江苏、湖北等7个省的61个菵草种群对ACCase抑制剂和ALS抑制剂的抗性情况，明确了抗性种群的分布和危害；通过生物测定和靶标酶基因分子检测，分离了不同抗药性生物型，包括单抗ACCase 抑制剂的不同位点发生突变的生物型，单抗ALS抑制剂的发生突变和未发生突变的生物型，对两类除草剂均表现抗性的生物型，并对这些不同的生物型进行繁殖；通过生物测定和靶标酶活性检测分析了不同生物型的交互抗性模式及抗性水平，明确了靶标酶基因不同突变类型对两类除草剂的交互抗性模式存在差异；通过转录组分析，筛选出非靶标抗性生物型中差异表达基因，初步明确P450、GST、酯酶、过氧化物酶、ABC转运蛋白等与WC10-10对ALS抑制剂产生非靶标抗性有关，GST、ABC转运蛋白、UDP-糖基转移酶、蛋白激酶等与WC11-48对ALS抑制剂产生抗性有关，GST、抗病蛋白、免疫蛋白、氧化酶等与WC11-48对ACCase抑制剂产生抗性有关；通过检测自然杂交率，明确了抗药性基因在种群间存在通过花粉扩散的风险。明确菵草对ACCase和ALS抑制剂这两类主要除草剂的抗性机制，能够为抗药性菵草的科学监测和治理提供依据。