College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China.
Pest Manag Sci. 2011 Feb;67(2):191-8. doi: 10.1002/ps.2050.
The efficacy of benzimidazole fungicides is often limited by resistance, and this is the case with the use of carbendazim for controlling Fusarium head blight caused by Gibberella zeae (Schwein.) Petch (anamorph Fusarium graminearum). Recent studies have shown that carbendazim resistance in field strains of G. zeae is associated with mutations in the β(2)-tubulin gene. The aims of the present study were to validate this mechanism and research the binding sites of carbendazim on β(2)-tubulin.
This work used site-directed mutagenesis followed by gene replacement to change the β(2)-tubulin gene of a carbendazim-sensitive field strain of G. zeae at residues 50, 167, 198 or 200. The transformants were confirmed and tested for their sensitivity to carbendazim. All the mutants were resistant to carbendazim, but the level of resistance differed depending on the mutation. Biological characteristics did not differ between the field strain and the site-directed mutants. A three-dimensional model of β(2)-tubulin was constructed, and the possible carbendazim binding site was analysed.
Mutations at codons 50, 167, 198 and 200 of G. zeae β(2)tub could cause resistance to carbendazim, and these codons may form a binding pocket.
苯并咪唑类杀菌剂的功效常常受到抗药性的限制，这也是使用多菌灵来防治由禾谷镰刀菌（Gibberella zeae (Schwein.) Petch，无性型为禾谷镰孢菌（Fusarium graminearum））引起的小麦赤霉病的情况。最近的研究表明，禾谷镰刀菌田间菌株对多菌灵的抗药性与β（2）-微管蛋白基因的突变有关。本研究旨在验证这一机制，并研究多菌灵在β（2）-微管蛋白上的结合位点。
本工作使用定点突变和基因替换，在多菌灵敏感的禾谷镰刀菌田间菌株的β（2）-微管蛋白基因的 50、167、198 或 200 位氨基酸处发生突变。转化子被确认并进行多菌灵敏感性测试。所有突变体对多菌灵均有抗性，但抗性水平因突变而异。田间菌株和定点突变体的生物学特性没有差异。构建了β（2）-微管蛋白的三维模型，并分析了可能的多菌灵结合位点。
禾谷镰刀菌β（2）-微管蛋白的密码子 50、167、198 和 200 发生突变可能导致对多菌灵的抗性，这些密码子可能形成一个结合口袋。
