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为评价西瓜蔓枯病菌对啶酰菌胺的抗性风险,了解其抗性机理,室内通过药剂驯化方法获得2株啶酰菌胺的抗性突变体XF21-3和YC60-1,测定了抗性突变体的生物学特性,并通过对Sdh B基因片段的测序比对,分析了西瓜蔓枯病菌对啶酰菌胺的抗性机理。生物测定结果表明:啶酰菌胺对2株抗性突变体的EC_(50)值分别为108和124μg/m L,抗性倍数(RR)分别为1 007和1 347,均为高抗菌株;抗性突变体的菌丝生长速率和产孢量均大于亲本菌株,但其致病性与亲本菌株无显著差异,对外界环境渗透压的敏感性低于亲本菌株;此外,啶酰菌胺与萎锈灵、戊唑醇、乙霉威及醚菌酯之间均不存在交互抗性,但与噻呋酰胺之间存在交互抗性。Sdh B基因片段测序及比对结果表明,高抗性突变体中Sdh B亚基277位上的氨基酸所对应的碱基由CAC突变为TAC,即由组氨酸(His)突变为酪氨酸(Tyr)。研究表明,西瓜蔓枯病菌在药剂选择压力下容易形成啶酰菌胺的抗性群体,且抗性突变体的离体适合度高于亲本菌株,此外,啶酰菌胺与同类型杀菌剂噻呋酰胺之间存在交互抗性,因此认为西瓜蔓枯病菌对啶酰菌胺具有中等抗性风险;同时进一步验证了Sdh B亚基277位上的氨基酸突变(His→Tyr,CAC→TAC)是西瓜蔓枯病菌对啶酰菌胺产生抗性的原因。
To evaluate the resistance risk of Boscalid to boscalid and to understand the mechanism of its resistance, two Boscalid-resistant mutants XF21-3 and YC60-1 were obtained indoors through chemical domestication, The biological characteristics of the mutants were analyzed. The resistance mechanism of Boscalid against boscalid was analyzed by sequencing the Sdh B gene fragment. The results of bioassay showed that the EC50 values of boscalid against two resistant mutants were 108 and 124 μg / m L, respectively. The resistance multiples (RRs) were 1007 and 1 347, respectively, . The mycelial growth rate and sporulation of resistant mutant were greater than that of the parental strain, but the pathogenicity of the resistant mutant was not significantly different from that of the parental strain, but less sensitive to the external environment osmotic pressure than the parental strain. In addition, There was no cross-resistance with auristatin, tebuconazole, diethylmethoxine and kresoxim-methyl, but there was interaction resistance with thifluzamide. Sequencing and alignment of the Sdh B gene fragment showed that the base corresponding to the amino acid at position 277 of the Sdh B subunit in the highly resistant mutant was changed from CAC to TAC, that is, the mutation from histidine (His) to tyrosine (Tyr). The results showed that the resistant population of boscalid could easily form the resistant population of boscalid, and the adaptability in vitro of the resistant mutant was higher than that of the parental strain. In addition, boscalid and the same fungicide thiophene Therefore, it is considered that there is a risk of intermediate resistance to boscalid in watermelon. At the same time, it is further verified that the amino acid mutation (His → Tyr, CAC → TAC) at position 277 of Sdh B subunit is The reason of resistance to boscalid in watermelon germ bacterium.