Chacra Experimental Integrada Barrow (MDA-INTA), National Scientific and Technical Research Council (CONICET), Faculty of Agronomy, National University of La Pampa, La Pampa, Argentina.
Department of Agroforestry, Plant Biochemistry and Molecular Biology, University of Cordoba, Cordoba, Spain.
Pest Manag Sci. 2022 Jul;78(7):3135-3143. doi: 10.1002/ps.6940. Epub 2022 May 9.
Digitaria sanguinalis has been identified as a species at high risk of evolving herbicide resistance, but thus far, there are no records of resistance to glyphosate. This weed is one of the most common weeds of summer crops in extensive cropping areas in Argentina. It shows an extended period of seedling emergence with several overlapping cohorts during spring and summer, and is commonly controlled with glyphosate. However, a D. sanguinalis population was implicated as a putative glyphosate-resistant biotype based on poor control at recommended glyphosate doses.
The field-collected D. sanguinalis population (Dgs R) from the Rolling Pampas has evolved glyphosate resistance. Differences in plant survival and shikimate levels after field-recommended and higher glyphosate doses were evident between Dgs R and the known susceptible (Dgs S) population; the resistance index was 5.1. No evidence of differential glyphosate absorption, translocation, metabolism or basal EPSPS activity was found between Dgs S and Dgs R populations; however, a novel EPSPS Pro-106-His point substitution is probably the primary glyphosate resistance-endowing mechanism. EPSPS in vitro enzymatic activity demonstrated that an 80-fold higher concentration of glyphosate is required in Dgs R to achieve similar EPSPS activity inhibition to that in the Dgs S population.
This study reports the first global case of glyphosate resistance in D. sanguinalis. This unlikely yet novel transversion at the second position of the EPSPS 106 codon demonstrates the intensity of glyphosate pressure in selecting unexpected glyphosate resistance alleles if they retain EPSPS functionality. © 2022 Society of Chemical Industry.
狗尾草已被确定为一种具有高进化为抗除草剂风险的物种，但迄今为止，尚未有其对草甘膦产生抗性的记录。这种杂草是阿根廷广泛种植区夏季作物中最常见的杂草之一。它具有较长的幼苗出土期，并在春季和夏季有几个重叠的群体，通常用草甘膦进行控制。然而，由于在推荐的草甘膦剂量下控制效果不佳，一个狗尾草种群被认为是具有潜在抗草甘膦的生物型。
从滚动潘帕斯草原采集的田间狗尾草种群（Dgs R）已经进化出了对草甘膦的抗性。在田间推荐剂量和更高剂量的草甘膦处理后，Dgs R 和已知的敏感（Dgs S）种群之间的植物存活率和莽草酸水平存在差异；抗性指数为 5.1。在 Dgs S 和 Dgs R 种群之间未发现草甘膦吸收、转运、代谢或基础 EPSPS 活性的差异；然而，可能是一种新的 EPSPS Pro-106-His 点取代是赋予草甘膦抗性的主要机制。体外酶活实验表明，Dgs R 中需要 80 倍更高浓度的草甘膦才能达到与 Dgs S 种群相似的 EPSPS 活性抑制。
本研究报告了全球首例狗尾草对草甘膦的抗性。EPSPS 106 密码子第二位的这种不太可能但新颖的颠换表明，如果它们保留 EPSPS 功能，草甘膦压力会选择出意想不到的草甘膦抗性等位基因。 © 2022 化学工业协会。
