Wang Guangfei, Ma Yan
Wei Sheng Wu Xue Bao. 2015 May 4;55(5):627-34.
The environmental fitness of metalaxyl-resistant isolate of Phytophthora capsici was studied for assessing the risk of metalaxyl-resistant P. capsici.
We studied the main biological characteristics, competitive ability on plate, pathogenicity on pepper plant and adaptability in soil of the laboratory-induced metalaxyl-resistant isolate of P. capsici (Pc2-3 strain), with the metalaxyl-sensitive isolate (Pc2 strain, the wild-type) as the control.
The zoosporangia production, releasing rate of zoosporangia and germination rate of zoospores of Pc2-3 were less than that of Pc2. The temperature range, optimum temperature range and initial pH range for mycelia growth of Pc2-3 were consistent with that of Pc2, but mycelia growth rate of Pc2-3 was lower than that of Pc2. Pc2-3 exhibited significantly weak competitive ability compared with Pc2 on carrots plate. Disease incidence of pepper inoculated with Pc2-3 (14.3%) was significantly lower than that of Pc2 (88. 6% ). When pepper plant was inoculated by mixtures of zoospore suspension of Pc2-3 and Pc2 at same ratio, the disease incidence, closing to that by Pc2 strain, was 75.7% . And all the strains isolated from diseased plants in the treatment were metalaxyl-sensitive. The density of P. capsis Pc2-3 was 0.28 times of Pc2 after the soil inoculated with Pc2-3 and Pc2 respectively at same zoospores density was incubated for 20 days. Otherwise, the ratio of Pc2-3 to Pc2 was 0.42 if the metalaxyl concentration in the soil was 300 mg/kg dry soil. No matter the soil temperature and humidity were beneficial to survival of P. capsici or not, Pc2-3 showed lower soil adaptability than Pc2.
The environmental fitness of metalaxyl-resistant P. capsis Pc2-3 was weaker than the metalaxyl- sensitive strain Pc2 (the wild-type).
研究辣椒疫霉甲霜灵抗性菌株的环境适合度，以评估辣椒疫霉甲霜灵抗性菌株的风险。
以甲霜灵敏感菌株（Pc2菌株，野生型）为对照，研究了实验室诱导的辣椒疫霉甲霜灵抗性菌株（Pc2-3菌株）的主要生物学特性、平板竞争能力、对辣椒植株的致病性及在土壤中的适应性。
Pc2-3的游动孢子囊产量、游动孢子囊释放率和游动孢子萌发率均低于Pc2。Pc2-3菌丝生长的温度范围、最适温度范围和初始pH范围与Pc2一致，但Pc2-3的菌丝生长速率低于Pc2。在胡萝卜平板上，Pc2-3与Pc2相比表现出明显较弱的竞争能力。接种Pc2-3的辣椒发病率（14.3%）显著低于接种Pc2的发病率（88.6%）。当以相同比例混合Pc2-3和Pc2的游动孢子悬浮液接种辣椒植株时，发病率为75.7%，接近接种Pc2菌株的发病率。且处理中从病株上分离的所有菌株对甲霜灵敏感。在相同游动孢子密度下分别接种Pc2-3和Pc2的土壤培养20天后，辣椒疫霉Pc2-3的密度是Pc2的0.28倍。否则，当土壤中甲霜灵浓度为300mg/kg干土时，Pc2-3与Pc2的比例为0.42。无论土壤温度和湿度是否有利于辣椒疫霉的生存，Pc2-3在土壤中的适应性均低于Pc2。
辣椒疫霉甲霜灵抗性菌株Pc2-3的环境适合度弱于甲霜灵敏感菌株Pc2（野生型）。
