浙江省西(甜)瓜蔓枯病菌对甲基硫菌灵和啶酰菌胺的抗性检测及抗性机制

Resistance monitoring and mechanism of Stagonosporppsis citrulli to thiophanate methyl and boscalid in Zhejiang Province

从浙江省5地采集了112株西(甜)瓜蔓枯病菌Stagonosporppsis citrulli,采用区分剂量法检测其对苯并咪唑类杀菌剂甲基硫菌灵(以下简称Ben)和琥珀酸脱氢酶抑制剂类(SDHIs)杀菌剂啶酰菌胺(简称Bos)的抗性。结果显示:112株西(甜)瓜蔓枯病菌对Ben和Bos的抗药性频率分别为100%和28.6%,其中对甲基硫菌灵产生高水平抗性(Ben^(HR))的菌株达100%,对啶酰菌胺产生低水平抗性(Bos^(LR))和高水平抗性(BosHR)的菌株分别为18.8%和9.8%。抗药性分子机制研究表明:Ben^(HR)菌株中β-tubulin的第198位氨基酸由Glu(E)突变成了Ala(A);BosHR菌株中Sdh B的第277位氨基酸由His(H)突变成了Tyr(Y),但Bos^(LR)的抗性机制还需进一步研究。研究结果表明,浙江省西(甜)瓜蔓枯病菌对苯并咪唑类杀菌剂甲基硫菌灵的抗性已十分严重,尽管大多数菌株对啶酰菌胺仍表现敏感,但在一些地区已存在高水平抗性菌株,应在加强抗药性监测的同时,注意SDHIs类杀菌剂的科学使用。

A total of 112 isolates of Stagonosporppsis citrulli were collected from 5 locations in Zhejiang Province.The resistance to thiophanate-methyl(Ben)and boscalid(Bos)was detected by the method of differentiated doses.The results showed that the respective resistance frequencies were 100%and 28.6%to Ben and Bos,respectively.The high-level resistance(Ben^(HR))of thiophanate-methyl reached 100%,and the low-level resistance(Bos^(LR))and high-level resistance(BosHR)of boscalid were 18.8%and 9.8%,respectively.Further studies on the molecular mechanism of resistance showed that the Ben^(HR) of S.citrulli was caused by the E198A point mutation inβ-tubulin,which was the mutation of 198th amino acid of from Glu(E)to Ala(A).The mechanism of BosHR was the point mutation in 277th amino acid of Sdh B from His(H)to Tyr(Y),but the mechanism of low-level resistance(Bos^(LR))still needs to be studied.To sum up,the resistance of S.citrulli population to benzimidazole fungicides in Zhejiang Province was very serious.Most isolates were sensitive to boscalid,but the high-level resistance has occurred in some regions.Therefore,attention should be paid to the scientific use of SDHIs and resistance monitoring should be strengthened.