重庆地区辣椒疫霉对氟吡菌胺的敏感性及抗性突变体的生物学性状

为明确重庆地区辣椒疫霉对氟吡菌胺的抗性风险，采用菌丝生长速率法测定了采自重庆未使用过氟吡菌胺地区的110株辣椒疫霉菌株对氟吡菌胺的敏感性，并对辣椒疫霉抗氟吡菌胺突变体的诱导方法及抗性突变体的主要生物学性状进行了研究。结果表明:110株辣椒疫霉对氟吡菌胺的EC₅₀平均值为(0.32 ± 0.11) μg/mL，不同菌株的敏感性频率呈连续单峰曲线分布，未出现敏感性明显下降的亚群体，因此可将该EC₅₀平均值作为重庆地区辣椒疫霉对氟吡菌胺田间抗性监测的敏感基线。通过紫外诱导菌丝体的方法，共获得3株可稳定遗传的抗氟吡菌胺突变体，抗性倍数介于69.5~98.5之间，突变频率为0.86%；抗性突变体BS11-5-1与亲本菌株BS11-5在菌丝生长速率、温度适应性、产孢子囊能力及致病力方面均无显著差异，而抗性突变体JLP11-4-2和JLP11-4-3在菌丝生长速率、温度适应性、产孢子囊能力及致病力方面均显著低于亲本菌株JLP11-4；不同抗性突变体对渗透压的敏感性与亲本菌株之间均存在不同程度差异；3个抗性突变体对Biolog PM1中95种碳源的利用情况与亲本菌株基本相似。交互抗性测定表明，辣椒疫霉抗氟吡菌胺突变体对甲霜灵、霜脲氰、烯酰吗啉、丁吡吗啉及嘧菌酯之间均不存在交互抗性，建议可将氟吡菌胺与上述几种杀菌剂交替或混合使用。

Sensitivity to fluopicolide and biological characteristics of resistant mutants of Phytophthora capsici in Chongqing

In order to clarify sensitivity of Phytophthora capsici to fluopicolide in Chongqing, the sensitivities of 110 isolates of P. capsici collected from areas in Chongqing without a history of fluopicolide appilication were determined by mycelial growth rate method. Resistance induction methods were conducted and main biological characters of the laboratory-induced fluopicolide-resistant mutants of P. capsici were studied. The results showed that the sensitivity frequency of isolates to fluopicolide distributed as a unimodal curve, and no sub-group with declining sensitivity was detected. The mean EC₅₀ value was (0.32 ± 0.11) μg/mL, which could be considered as the sensitivity baseline of P. capsici to fluopicolide and could be used for the field resistance monitoring. Three stable genetic fluopicolide-resistant mutants were acquired by UV irradiating mycelia. The resistance ratio ranged from 69.5 to 98.5 and the mutation frequency was 0.86%. It was found that the resistant strain BS11-5-1 showed similarity in mycelial growth rate, temperature adaptability, sporulation, pathogenicity, compared with its sensitive parent BS11-5. But biological characteristics of resistant mutants JLP11-4-2 and JLP11-4-3 were significantly lower than their parental isolate JLP11-4. The sensitivities of different resistant mutants to osmotic pressure were different from that of their parents. Utilization of 95 kinds of carbon sources of 3 resistant mutants was similar with their respective parents. No cross resistance existed between fluopicolide and metalaxyl, cymoxanil, dimethomorph, pyrimorph and azoxystrobin. It is suggested that the fluopicolide should be used alternately or as a mixture with other not cross-resistant fungicides.