College of Agronomy, Northeast Agricultural University, Harbin 150030, Heilongjiang, PR China.
Lingnan Normal University, ZhanJiang 524048, Guang Dong, PR China.
Pestic Biochem Physiol. 2022 Mar;182:105031. doi: 10.1016/j.pestbp.2021.105031. Epub 2022 Jan 1.
Glyphosate is a broad-spectrum and nonselective organophosphorus herbicide that inhibits 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), an enzyme in the shikimate pathway in plants. A glyphosate-resistant fungus identified as Fusarium verticillioides was screened from soil subjected to long-term glyphosate application, and this fungus could grow in inorganic salt medium containing 90 mmol/L glyphosate. The optimum culture conditions identified via the response surface curve method were 28 °C and pH 7.0. The target gene epsps was cloned in this study, and the open reading frame contained 1170 nucleotides and putatively encoded 389 amino acid residues. Phylogenetic analysis showed that this gene belonged to class I, genes naturally sensitive to glyphosate. q-PCR confirmed that the relative expression level of the epsps gene was low, and no significant difference in expression was observed among different glyphosate concentrations at 12 h or 48 h. On day 28, the degradation by Fusarium verticillioides C-2 of sterilized soil and unsterilized soil supplemented with 60 mg/kg glyphosate reached 72.17% and 89.07%, respectively, and a significant difference was observed between the treatments with and without the glyphosate-degrading strain. The recovery of soil dehydrogenase activity after the addition of Fusarium verticillioides was significantly higher than that in the absence of the degrading fungus on the 28th day. The results showed that C-2 is a highly effective glyphosate-degrading strain with bioremediation potential for glyphosate-contaminated soil.
草甘膦是一种广谱、非选择性的有机磷除草剂，它抑制植物中莽草酸途径中的 5-烯醇丙酮酰莽草酸-3-磷酸合酶（EPSPS）。从长期施用草甘膦的土壤中筛选出一种抗草甘膦的真菌，鉴定为轮枝镰孢菌（Fusarium verticillioides），该真菌可以在含有 90mmol/L 草甘膦的无机盐培养基中生长。通过响应面曲线法确定的最佳培养条件为 28°C 和 pH 7.0。本研究克隆了靶基因 epsps，其开放阅读框包含 1170 个核苷酸，推测编码 389 个氨基酸残基。系统发育分析表明，该基因属于 I 类，对草甘膦天然敏感的基因。q-PCR 证实 epsps 基因的相对表达水平较低，在 12h 和 48h 时，不同草甘膦浓度下的表达水平没有显著差异。第 28 天时，轮枝镰孢菌 C-2 对添加 60mg/kg 草甘膦的灭菌土壤和未灭菌土壤的降解率分别达到 72.17%和 89.07%，添加和不添加草甘膦降解菌的处理之间存在显著差异。添加轮枝镰孢菌后，土壤脱氢酶活性的恢复明显高于不添加降解菌的情况。结果表明，C-2 是一种高效的草甘膦降解菌，具有修复草甘膦污染土壤的潜力。
