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为鉴定1株分离自口红吊兰叶部病斑上的疑似核盘菌菌株,利用柯赫氏法则验证其致病性并通过形态观察和ITS序列分析对该病原菌进行分类鉴定,结合温度、酸碱度等生理指标研究其生物学特性,并利用菌丝生长速率法测定了扑海因、多菌灵、苯醚甲环唑、腐霉利4种药剂对该病原菌的抑制作用。结果显示:在PDA平板上该病原菌菌丝为白色,均匀生长;约7 d后开始产生菌核,直径3~5 mm;菌核萌发后可产生1~3个子囊盘,内含8个大小为8.0~12.0μm×4.0~5.5μm的子囊孢子。该菌株ITS序列系统进化分析结果显示,其与核盘菌的同源性高达99%。综上所述,初步确定该菌株为核盘菌Sclerotinia sclerotiorum。该病原菌在PDA培养基上的最适生长温度为20~25℃、最适生长p H为5~7。室内毒力测定发现供试4种药剂中扑海因对该病原菌菌丝生长有较好的抑制效果,且其EC_(50)最小,仅为0.62 mg/L,证明扑海因对核盘菌毒力最强。
In order to identify a strain of S. sclerotiorum isolated from the leaf spot of Portulaca lipra, its pathogenicity was tested by Koch’s law and the pathogen was identified by morphological observation and ITS sequence analysis. The temperature, pH, etc. Physiological indicators of its biological characteristics, and the use of mycelial growth rate method for the determination of the puihin, carbendazim, difenoconazole, pyrethrin four kinds of agents on the pathogenic bacteria inhibition. The results showed that the mycelium of the pathogen was white and grew evenly on the PDA plate. The sclerotia began to produce sclerotiorum with a diameter of 3 to 5 mm after about 7 days. The sclerotia of the sclerotia produced 1 to 3 ascus plates with 8 sizes Is 8.0 to 12.0 μm × 4.0 to 5.5 μm ascospores. Phylogenetic analysis of the ITS sequence showed that the homology of the ITS was 99%. In summary, preliminary identification of the strain Sclerotinia sclerotiorum. The optimal growth temperature of the pathogen on PDA medium is 20 ~ 25 ℃, and the optimum growth pH is 5 ~ 7. The results of indoor toxicity test showed that mepivacaine had a good inhibitory effect on the mycelial growth of the pathogen in four kinds of medicaments, and its EC50 was the lowest (0.62 mg / L) Most virulent.