College of Plant Protection, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
College of Plant Protection, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
Pestic Biochem Physiol. 2018 Apr;146:80-89. doi: 10.1016/j.pestbp.2018.03.001. Epub 2018 Mar 7.
Cyprodinil belongs to the chemical class of anilinopyrimidines fungicides. In this study, baseline sensitivity of Sclerotinia sclerotiorum (Lib.) de Bary to cyprodinil was determined using 100 strains collected from the fields in Jiangsu Province of China. The EC (50% effective concentration) values ranged from 0.0636-0.8163 μg/ml with a mean value of 0.1869 (±0.1118) ug/ml for mycelial growth. Nine cyprodinil-resistant mutants (Range of resistance factor: 20.22-271.59) were obtained from sensitive strains exposed on PDA medium amended with cyprodinil and the resistance was stable after their ten transfers on PDA without the fungicide or stored at 4 °C for two months. There was positive cross-resistance between cyprodinil and pyrimethanil but not to fludioxonil, dimetachlone, procymidone, carbendazim and boscalid in S. sclerotiorum. Compared with the parental strains, all of the nine cyprodinil-resistant mutants decreased in sclerotial production. The dry weight of mycelia, pathogenicity and cell membrane permeability of most resistant mutants decreased. The mycelial growth, oxalic acid content, and the response to various stress for resistant mutants were almost the same as the sensitive parental strains. Sequencing alignment results showed that there was no alteration of amino acid in cystathionine γ-synthase (MetB) and cystathionine β-lyase (MetC) between cyprodinil-resistant mutants and their sensitive parental strains, which indicated that MetB or MetC was not the molecular target of cyprodinil in S. sclerotiorum. The addition of amino acids L-methionine, L-cystine or L-cysteine decreased the inhibition of cyprodinil against mycelial growth of S. sclerotiorum, which indicated that cyprodinil could not only inhibited methionine biosynthesis but also suppressed cystine and cysteine biosynthesis. These results will contribute to evaluating the resistance risk of cyprodinil for management of the plant diseases of Sclerotinia stem rot caused by S. sclerotiorum and further increase our understanding about the mode of action of cyprodinil.
腐霉利属于嘧啶胺类杀菌剂。本研究采用菌丝生长速率法，测定了采自中国江苏省的 100 株核盘菌对腐霉利的敏感性。结果表明，供试菌株对腐霉利的 EC50 值在 0.0636-0.8163μg/ml 之间，平均值为 0.1869(±0.1118)μg/ml。从敏感菌株经腐霉利处理的 PDA 平板上筛选获得了 9 株抗腐霉利突变株（抗性倍数范围：20.22-271.59），突变株在不含腐霉利的 PDA 平板上连续传代 10 次或在 4℃下保存 2 个月后，其抗性仍稳定。在核盘菌中，腐霉利与嘧啶胺之间存在正交互抗性，但与氟啶胺、二甲噻草酮、丙森锌、多菌灵和肟菌酯之间无交互抗性。与亲本菌株相比，9 株腐霉利抗性突变株的菌核产量均降低。其中，大部分抗性突变株的菌丝干重、致病性和细胞膜通透性降低。抗性突变株的菌丝生长、草酸含量以及对各种胁迫的响应与敏感亲本菌株几乎相同。测序比对结果表明，腐霉利抗性突变株与其敏感亲本菌株的半胱氨酸γ-合酶（MetB）和半胱氨酸β-裂合酶（MetC）的氨基酸均未发生改变，这表明 MetB 或 MetC 不是核盘菌中腐霉利的作用靶标。添加氨基酸 L-蛋氨酸、L-胱氨酸或 L-半胱氨酸降低了腐霉利对核盘菌菌丝生长的抑制作用，这表明腐霉利不仅能抑制蛋氨酸的生物合成，还能抑制胱氨酸和半胱氨酸的生物合成。这些结果将有助于评估腐霉利对核盘菌引起的植物病害（如菌核病）的抗性风险，并进一步提高我们对腐霉利作用方式的认识。
