Goh Sou Sheng, Vila-Aiub Martin M, Busi Roberto, Powles Stephen B
Australian Herbicide Resistance Initiative, School of Plant Biology, University of Western Australia, WA, Australia.
IFEVA-CONICET, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina.
Pest Manag Sci. 2016 Jan;72(1):67-73. doi: 10.1002/ps.4005. Epub 2015 Apr 8.
A population of Echinochloa colona infesting agricultural fields in the northern region of Western Australia evolved glyphosate resistance after 10 years of glyphosate selection. This study identified two phenotypic (susceptible S versus resistant R) lines from within a segregating glyphosate-resistant population. Estimation of survival, growth and reproductive rates of the phenotypes in response to glyphosate selection helped to characterise the level of resistance, fitness and the selection intensity for glyphosate in this species.
Estimations of LD(50) (lethal dose) and GR(50) (growth rate) showed an eightfold glyphosate resistance in this population. The resistant index based on the estimation of seed number (SY(n50)) showed a 13-fold resistance. As a result of linear combination of plant survival and fecundity rates, plant fitness values of 0.2 and 0.8 were estimated for the S and R phenotypes when exposed to the low dose of 270 g glyphosate ha(-1). At the recommended dose of 540 g glyphosate ha(-1) , fitness significantly decreased (fivefold) in S plants but remained markedly similar (0.7) in plants of the R phenotype. Thus, the calculated selection intensity (SI) at 540 g glyphosate ha(-1) was much greater (SI = 17) than at 270 g glyphosate ha(-1) (SI = 4).
The assessment of plant survival and fecundity in response to glyphosate selection in the S and R phenotypes allowed a greater accuracy in the estimation of population fitness of both phenotypes and thus of glyphosate selection intensity in E. colona. The estimation of seed number or mass of phenotypes under herbicide selection is a true ecological measure of resistance with implications for herbicide resistance evolution.
在西澳大利亚北部地区，侵染农田的一群马唐在经过10年草甘膦选择后进化出了草甘膦抗性。本研究从一个分离的抗草甘膦群体中鉴定出两个表型品系（敏感型S与抗性型R）。评估这些表型在草甘膦选择下的存活、生长和繁殖率，有助于确定该物种对草甘膦的抗性水平、适合度以及选择强度。
半数致死剂量（LD(50)）和半数生长率（GR(50)）的估算表明，该群体对草甘膦具有8倍抗性。基于种子数量估算的抗性指数（SY(n50)）显示出13倍抗性。由于植物存活率和繁殖率的线性组合，当暴露于270 g草甘膦·ha⁻¹的低剂量时，S型和R型表型植物的适合度值分别估计为0.2和0.8。在540 g草甘膦·ha⁻¹的推荐剂量下，S型植物的适合度显著下降（5倍），而R型表型植物的适合度仍显著相似（0.7）。因此，在540 g草甘膦·ha⁻¹时计算出的选择强度（SI）比在270 g草甘膦·ha⁻¹时大得多（SI = 17）（SI = 4）。
评估S型和R型表型对草甘膦选择的植物存活和繁殖情况，能够更准确地估计两种表型的群体适合度，进而更准确地估计马唐中草甘膦的选择强度。在除草剂选择下对表型种子数量或质量的估算，是一种真正的抗性生态测量方法，对除草剂抗性进化具有重要意义。
