Department of Agronomy, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, 4918943464, Iran.
Department of Agricultural Chemistry and Soil Science, University of Córdoba, 14014, Córdoba, Spain.
Plant Physiol Biochem. 2020 Jun;151:681-688. doi: 10.1016/j.plaphy.2020.03.037. Epub 2020 Apr 20.
Herbicides that inhibit acetyl-coenzyme A carboxylase (ACCase) are commonly used to control weedy grasses such as short-spike canarygrass (Phalaris brachystachys). Two resistant biotypes of P. brachystachys (R1 and R2) were found in different winter wheat fields in Iran. This study was done to confirm the suspected resistance observed in the field and to elucidate the resistance mechanisms involved. The results indicated that the both resistant biotypes showed cross-resistance to diclofop-methyl (DM), pinoxaden (PN) and cycloxydim (CD) herbicides. Based on the herbicide dose that inhibited 50% of the ACCase activity (I), the ACCase activity of the resistant biotypes was less sensitive than the S biotype to DM, CD, and PN. No differences in translocation were detected between biotypes; most of the herbicide remained in the treated leaves. The C-DM metabolites were identified using thin-layer chromatography. Pre-treatment with the cytochrome P450 inhibitor ABT inhibited C-DM metabolism in the R1 biotype, indicating that metabolism is involved in the DM resistance in the R1 biotype. DNA sequencing studies found an Ile-1781-Thr change in both resistant biotypes, conferring cross-resistance to ACCase inhibitors. In general, in the R1 biotype which showed a higher level of resistance than that of the R2 biotype, cross-resistance was observed because of mutation and DM metabolism, while in the R2 biotype, the mutation confers resistance to ACCase-inhibiting herbicides. This is the first reported evidence of the mechanisms responsible for the resistance to ACCase herbicides in P. brachystachys. These results could be useful for improved management of resistant biotypes carrying similar mutations.
乙酰辅酶 A 羧化酶（ACCase）抑制剂除草剂常用于控制杂草草，如短芒雀麦（Phalaris brachystachys）。在伊朗的不同冬麦田中发现了两种具有抗性的短芒雀麦生物型（R1 和 R2）。本研究旨在确认田间观察到的疑似抗性，并阐明涉及的抗性机制。结果表明，两种抗性生物型对氟吡草酮（DM）、吡氟草酮（PN）和环丙氧草酯（CD）除草剂表现出交叉抗性。基于抑制 50%乙酰辅酶 A 羧化酶活性（I）的除草剂剂量，与 S 生物型相比，抗性生物型的乙酰辅酶 A 羧化酶活性对 DM、CD 和 PN 的敏感性降低。在生物型之间未检测到转运差异；大部分除草剂仍留在处理叶片中。使用薄层层析法鉴定 C-DM 代谢物。在用细胞色素 P450 抑制剂 ABT 预处理后，R1 生物型中的 C-DM 代谢被抑制，表明代谢参与了 R1 生物型中 DM 抗性。DNA 测序研究发现两种抗性生物型都存在 Ile-1781-Thr 变化，赋予对乙酰辅酶 A 羧化酶抑制剂的交叉抗性。一般来说，在 R1 生物型中，由于突变和 DM 代谢，观察到交叉抗性，而在 R2 生物型中，突变赋予对乙酰辅酶 A 羧化酶抑制剂的抗性。这是首次报道短芒雀麦对乙酰辅酶 A 羧化酶抑制剂产生抗性的机制。这些结果可能有助于对携带类似突变的抗性生物型进行更好的管理。
