Department of Biosciences, Durham University, South Road, Durham, DH1 3LE, United Kingdom.
Sci Rep. 2017 Feb 15;7:42565. doi: 10.1038/srep42565.
Emergence of glyphosate-resistant horseweed (Conyza canadensis) biotypes is an example of how unrelenting use of a single mode of action herbicide in agricultural weed control drives genetic adaptation in targeted species. While in other weeds glyphosate resistance arose from target site mutation or target gene amplification, the resistance mechanism in horseweed uses neither of these, being instead linked to reduced herbicide uptake and/or translocation. The molecular components underpinning horseweed glyphosate-resistance remain unknown. Here, we used an in vitro leaf disc system for comparative analysis of proteins extracted from control and glyphosate-treated tissues of glyphosate-resistant and glyphosate-susceptible biotypes. Analysis of shikimic acid accumulation, ABC-transporter gene expression, and cell death were used to select a suitable glyphosate concentration and sampling time for enriching proteins pivotal to glyphosate resistance. Protein gel analysis and mass spectrometry identified mainly chloroplast proteins differentially expressed between the biotypes before and after glyphosate treatment. Chloroplasts are the organelles in which the shikimate pathway, which is targeted by glyphosate, is located. Calvin cycle enzymes and proteins of unknown function were among the proteins identified. Our study provides candidate proteins that could be pivotal in engendering resistance and implicates chloroplasts as the primary sites driving glyphosate-resistance in horseweed.
抗草甘膦的加拿大飞蓬生物型的出现，就是一个例子，说明了在农业杂草防治中，持续单一作用模式的除草剂的使用，如何导致目标物种的遗传适应性。虽然在其他杂草中，草甘膦抗性是由于靶标位点突变或靶标基因扩增引起的，但在飞蓬中，抗性机制既不依赖于靶标位点突变，也不依赖于靶标基因扩增，而是与减少除草剂吸收和/或转运有关。目前仍不清楚与飞蓬抗草甘膦相关的分子组成。在这里，我们使用体外叶片圆盘系统，对来自抗草甘膦和敏感生物型的对照和草甘膦处理组织中提取的蛋白质进行比较分析。分析莽草酸的积累、ABC 转运蛋白基因的表达和细胞死亡，以选择合适的草甘膦浓度和采样时间，从而富集与抗草甘膦相关的关键蛋白质。蛋白凝胶分析和质谱分析鉴定了草甘膦处理前后生物型之间差异表达的主要是质体蛋白。质体是莽草酸途径的细胞器，而草甘膦就是靶向该途径。鉴定出的蛋白包括卡尔文循环酶和功能未知的蛋白。我们的研究提供了可能在产生抗性方面具有关键作用的候选蛋白，并表明质体是驱动飞蓬抗草甘膦的主要部位。
