Department of Evolution, Ecology, and Organismal Biology; Ohio State University, Columbus, OH, 43210, USA.
Department of Horticulture and Crop Science; Ohio State University, Columbus, OH, 43210, USA.
Sci Rep. 2020 May 5;10(1):7577. doi: 10.1038/s41598-020-64458-7.
Documenting the diversity of mechanisms for herbicide resistance in agricultural weeds is helpful for understanding evolutionary processes that contribute to weed management problems. More than 40 species have evolved resistance to glyphosate, and at least 13 species have a target-site mutation at position 106 of EPSPS. In horseweed (Conyza canadensis), this p106 mutation has only been reported in Canada. Here, we sampled seeds from one plant (= biotype) at 24 sites in Ohio and 20 in Iowa, screened these biotypes for levels of resistance, and sequenced their DNA to detect the p106 mutation. Resistance categories were based on 80% survival at five glyphosate doses: S (0×), R1 (1×), R2 (8×), R3 (20×), or R4 (40×). The p106 mutation was not found in the19 biotypes scored as S, R1, or R2, while all 25 biotypes scored as R3 or R4 had the same proline-to-serine substitution at p106. These findings represent the first documented case of target-site mediated glyphosate resistance in horseweed in the United States, and the first to show that this mutation was associated with very strong resistance. We hypothesize that the p106 mutation has occurred multiple times in horseweed and may be spreading rapidly, further complicating weed management efforts.
记录农业杂草中除草剂抗性机制的多样性有助于理解导致杂草管理问题的进化过程。超过 40 种杂草已经对草甘膦产生了抗性，至少有 13 种杂草在 EPSPS 的第 106 位发生了靶位突变。在加拿大，已经报道了豚草（Conyza canadensis）中存在这种 p106 突变。在这里，我们从俄亥俄州的 24 个地点和爱荷华州的 20 个地点的一个植株（=生物型）中采集了种子，筛选了这些生物型的抗性水平，并对其 DNA 进行测序以检测 p106 突变。抗性类别基于 5 种草甘膦剂量下 80%的存活率：S（0×）、R1（1×）、R2（8×）、R3（20×）或 R4（40×）。在被评为 S、R1 或 R2 的 19 个生物型中没有发现 p106 突变，而在被评为 R3 或 R4 的 25 个生物型中都在第 106 位发生了脯氨酸到丝氨酸的取代。这些发现代表了美国豚草中靶标介导的草甘膦抗性的首例有记录案例，也是首例表明这种突变与很强的抗性有关的案例。我们假设 p106 突变已经在豚草中多次发生，并且可能正在迅速传播，这进一步增加了杂草管理的难度。
