Department of Crop Sciences, University of Illinois, Urbana, IL, USA.
USDA-ARS Global Change and Photosynthesis Research Unit, Urbana, IL, USA.
Pest Manag Sci. 2018 Feb;74(2):293-301. doi: 10.1002/ps.4706. Epub 2017 Sep 28.
The fitness cost of herbicide resistance (HR) in the absence of herbicide selection plays a key role in HR evolution. Quantifying the fitness cost of resistance, however, is challenging, and there exists a knowledge gap in this area. A synthetic (artificially generated) Amaranthus tuberculatus population segregating for five types of HR was subjected to competitive growth conditions in the absence of herbicide selection for six generations. Fitness costs were quantified by using a combination of phenotyping and genotyping to monitor HR frequency changes over generations.
In the absence of herbicide selection, a significant fitness cost was observed for resistance to acetolactate synthase-inhibiting herbicides, but not for resistances to atrazine (non-target-site resistance mechanism), protoporphyrinogen oxidase inhibitors, 4-hydroxyphenylpryuvate dioxygenase inhibitors or glyphosate. Glyphosate resistance was conferred by multiple mechanisms in the synthetic population, and further analysis revealed that one mechanism, amplification of the 5-enolypyruvylshikimate-3-phosphate synthase gene, did decrease in frequency.
Our results indicate that herbicide-resistance mitigation strategies (e.g. herbicide rotation) that rely on the existence of fitness costs in the absence of herbicide selection likely will be largely ineffective in many cases. © 2017 Society of Chemical Industry.
在没有除草剂选择的情况下，除草剂抗性（HR）的适应代价在 HR 进化中起着关键作用。然而，量化抗性的适应代价具有挑战性，并且在这方面存在知识差距。一个人工（人为产生的）马齿苋种群，分离出五种类型的 HR，在没有除草剂选择的情况下，经过六代的竞争生长条件。通过表型和基因型的组合来监测 HR 频率随世代的变化，从而量化适应代价。
在没有除草剂选择的情况下，观察到对乙酰乳酸合酶抑制剂除草剂的抗性存在显著的适应代价，但对莠去津（非靶标位点抗性机制）、原卟啉原氧化酶抑制剂、4-羟苯基丙酮酸双加氧酶抑制剂或草甘膦的抗性则没有适应代价。草甘膦抗性在人工种群中存在多种机制，进一步分析表明，一种机制，即 5-烯醇丙酮酸莽草酸-3-磷酸合酶基因的扩增，其频率降低。
我们的结果表明，依赖于没有除草剂选择时存在适应代价的除草剂抗性缓解策略（如除草剂轮作）在许多情况下可能基本无效。 © 2017 化学工业学会。
