School of Plant Protection, Anhui Agricultural University, Hefei 230036, China; Key Laboratory of Integrated Crop Pest Management of Anhui Province, School of Plant Protection, Anhui Agricultural University, Hefei 230036, China; Key Laboratory of Agri-products Quality and Biosafety (Anhui Agricultural University), Ministry of Education, Hefei 230036, China; Anhui Province Laboratory for Green Pesticide Development and Application, School of Plant Protection, Anhui Agricultural University, Hefei 230036, China.
Shandong Peanut Research Institute, Qingdao 266100, China.
Pestic Biochem Physiol. 2024 Aug;203:106025. doi: 10.1016/j.pestbp.2024.106025. Epub 2024 Jul 15.
Peanut web blotch (PWB) caused by Phoma arachidicola, is one of the most serious foliar diseases of peanut. Although prochloraz is an active fungicide with broad anti-fungal spectrum, it has not been registered for the control of PWB in China. The activity of prochloraz against P. arachidicola and the risk of resistance to prochloraz in P. arachidicola are still unclear. In current study, the inhibitory activity of prochloraz against 96 P. arachidicola strains was determined with the average EC value of 1.2700 ± 0.7786 μg/mL. Prochloraz exhibited excellent protective and curative effect on detached peanut leaves, and the effect was obviously better than that of carbendazim and difenoconazole at the same concentration. After prochloraz treatment, the mycelium of P. arachidicola contorted, shrunk and ruptured, with shrinking of cell wall and membrane, enhanced cell membrane permeability, and reduced ergosterol content. Totally 80 prochloraz-resistant mutants were obtained by fungicide adaptation with the frequency of 6.7 × 10. All the selected 12 prochloraz-resistant mutants lost their resistance to prochloraz after 10 transfers on PDA plates. And these mutants exhibited decreased biological fitness in mycelial growth and pathogenicity. Moreover, there was positive cross-resistance between prochloraz and other demethylation inhibitor (DMI) fungicides, such as tebuconazole, triflumizole and difenoconazole, but no cross-resistance was found between prochloraz and other classes of fungicides, such as carbendazim, pydiflumetofen or fludioxonil. Overexpression of PaCYP51 and PaAtrB genes were detected in the resistant mutants. All the above results demonstrated that prochloraz has a great potential in management of PWB. The risk of P. arachidicola developing resistance to prochloraz is relatively low-to-medium. Overexpressing of PaCYP51 and PaAtrB might be linked to prochloraz resistance in P. arachidicola.
花生褐斑病（PWB）由 Phoma arachidicola 引起，是花生最严重的叶部病害之一。虽然咯菌腈是一种具有广谱抗真菌活性的杀菌剂，但尚未在中国登记用于防治 PWB。咯菌腈对 P. arachidicola 的活性和 P. arachidicola 对咯菌腈产生抗药性的风险尚不清楚。在本研究中，用平均 EC 值为 1.2700±0.7786μg/mL 测定了咯菌腈对 96 株 P. arachidicola 菌株的抑制活性。咯菌腈对离体花生叶片具有优异的保护和治疗效果，效果明显优于相同浓度的多菌灵和三唑酮。咯菌腈处理后，P. arachidicola 的菌丝扭曲、收缩和破裂，细胞壁和膜收缩，细胞膜通透性增强，麦角甾醇含量降低。用杀菌剂适应性共获得 80 株咯菌腈抗性突变体，频率为 6.7×10-6。从 PDA 平板上选择的 12 个咯菌腈抗性突变体在 10 次传代后均失去了对咯菌腈的抗性。这些突变体在菌丝生长和致病性方面的生物适应性降低。此外，咯菌腈与其他脱甲基抑制剂（DMI）杀菌剂如戊唑醇、三氟咪啶和三唑酮之间存在正交互抗性，但与其他类别的杀菌剂如多菌灵、吡氟酰草胺或氟啶胺之间不存在交叉抗性。在抗性突变体中检测到 PaCYP51 和 PaAtrB 基因的过表达。所有这些结果表明咯菌腈在防治 PWB 方面具有很大的潜力。P. arachidicola 对咯菌腈产生抗药性的风险较低至中等。PaCYP51 和 PaAtrB 的过表达可能与 P. arachidicola 对咯菌腈的抗性有关。
