黄瓜霜霉病菌抗氟吗啉菌株的适合度研究

 采用离体叶盘法和活体植株法,测定了从田间分离获得的对氟吗啉具有抗药性的黄瓜霜霉病菌菌株和通过室内紫外线诱变获得的对氟吗啉及对照药剂烯酰吗啉和嘧菌酯产生抗药性的突变菌株的生存适合度。试验结果表明,室内诱导获得的氟吗啉和烯酰吗啉抗药性突变菌株的适合度明显低于敏感菌株和嘧菌酯抗药性突变体及田产氟吗啉抗药性菌株,主要表现在菌株的侵染率、产孢能力和致病力的减弱。室内获得的氟吗啉和烯酰吗啉抗药性突变体和敏感菌株混合接种、继代培养后,其抗药菌株的检出率在混合群体中逐渐降低,其中抗性突变体FR4和敏感菌株以2:8的比例混合接种、培养7代后,其无性后代中检测不到抗药性菌株的存在,表明室内氟吗啉抗药性突变体竞争力弱于敏感菌株;而田间氟吗啉抗药性菌株和室内嘧菌酯抗药性突变体则表现出和敏感菌株相似或更强的竞争力,预示田间自然情况下抗药性菌株存在着可能形成优势菌群而导致药剂防治失败的潜在风险。

Study on fitness of flumorph-resistant strains of Pseudoperonospora cubensis

The fitness of flumorph-resistant (FR) , dimethomorph-resistant (DR), azoxystrobin-resistant (AR) mutants, which all induced by ultraviolet irradiation, and field flumorph-resistant strains were compared with the methods of cucumber leaf discs or intact plant. The fitness of FR and DR mutants were decreased compared with that of their parent, AR mutants, and field FR strains, because of their lower infection frequency, lesion area and sporulation capacity.When mixtures of AR mutant or field flumorph-resistant strain with wild sensitive strain were inoculated onto leaf discs, all resistance mutant or strain exhibited a strong or similar competitive ability compared with sensitive strains: their proportion increased in the sporangial populations after 7 to 10 sporulation cycles. In contrast, FR and DR mutants showed weak competitive ability compared with sensitive strains. After seven successive transfers of an initial 2 :8 mixtures of FR4 mutant + sensitive strain, no FR4 resistant mutant were detected. The present results showed that there is the potential resistant risk for flumorph.