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【目的】研究抗甲霜灵辣椒疫霉菌的环境适合度,对于评估甲霜灵防治辣椒疫霉的抗药性风险具有重要意义。【方法】以室内药剂驯化的抗甲霜灵辣椒疫霉菌株Pc2-3为研究对象,分析比较其与原始敏感菌株Pc2的主要生物学特性、生长竞争力、致病力及土壤适合度等环境适合度指标。【结果】Pc2-3孢子囊产生量(3 d后)、孢子囊释放率(24 h后)和游动孢子萌发率(8 h后)分别是Pc2的0.44、0.09和0.54倍。Pc2-3可生长温度和p H范围及最适生长温度与Pc2基本一致,但菌丝生长速率低于Pc2。竞争力测定显示,在胡萝卜(CA)平板培养条件下,Pc2-3生长极显著弱于Pc2。盆栽致病试验显示,Pc2-3对辣椒植株的致病率为14.3%,明显低于Pc2(88.6%)。两者等量混合后接种,辣椒植株的发病率为75.7%,接近单独接种Pc2时的发病率,且所有病株分离出的辣椒疫霉菌均为甲霜灵敏感型。分别将Pc2-3和Pc2游动孢子加入自然土壤培养20 d后,实时定量PCR检测显示Pc2-3数量是Pc2的0.28倍,当土壤中含有300 mg/kg干土的甲霜灵,则前者为后者的0.42倍。此外,2个菌株最适存活土壤温度和湿度基本一致,当土壤温度和湿度利于辣椒疫霉存活时,Pc2-3土壤适合度显著低于Pc2,不利于辣椒疫霉存活时,Pc2-3土壤适合度略低于Pc2。【结论】抗甲霜灵菌株Pc2-3环境适合度弱于原始敏感菌株Pc2。
【Objective】 To study the environmental fitness of Phytophthora capsici resistant to metalaxyl is important for evaluating the resistance of metalaxyl to Phytophthora capsici. 【Method】 Pc2-3 resistant to metalaxyllammonium chloride was used as an object of study. The main biological characteristics, growth competitiveness, pathogenicity and soil fitness of Pc2-3 were analyzed and compared. Fitness index. 【Result】 The results showed that Pc2-3 sporulation volume (after 3 days), sporangial release rate (24 h) and zoospore germination rate (8 hrs) were 0.44, 0.09 and 0.54 times of Pc2, respectively. Pc2-3 growth temperature and pH range and the optimal growth temperature are basically the same with Pc2, but mycelial growth rate is lower than Pc2. Competitiveness measurements showed that Pc2-3 growth was significantly weaker than Pc2 under carrot (CA) plate culture conditions. The pathogenicity test of pot plants showed that the pathogenicity of Pc2-3 to pepper plants was 14.3%, which was significantly lower than that of Pc2 (88.6%). The two were inoculated by the same amount and then inoculated. The incidence of pepper plants was 75.7%, which was close to the incidence of Pc2 when inoculated alone. All P. capsici isolated from the diseased plants were metalaxyl sensitive. Pc2-3 and Pc2 spores were added to the soil after 20 days of culture, real-time quantitative PCR showed Pc2-3 Pc2 0.28 times, when the soil contains 300 mg / kg of metalaxyl, then the former 0.42 times for the latter. In addition, the optimum temperature and humidity of the two strains were basically the same. When soil temperature and humidity were favorable to the survival of Phytophthora capsici, the soil fitness of Pc2-3 was significantly lower than that of Pc2, which was unfavorable for the survival of P. capsici. The fitness is slightly lower than Pc2. 【Conclusion】 The environmental adaptability of metalaxyl-resistant strain Pc2-3 was weaker than that of the original sensitive strain Pc2.