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从患病的彭泽鲫卵上分离3株丝状真菌,经人工感染试验证实其中1株丝状真菌JL1对彭泽鲫卵具有致病性,并进一步研究了其形态与生长特性,开展了ITS rDNA序列分析。实验结果表明,菌株JL1菌丝为透明管状结构,中间无横隔,分枝较少;游动孢子囊多数呈棒状,游动孢子呈多排排列,发育成熟后从孢子囊中释放出来,并迅速游离;藏卵器呈球形,与雄器同枝或异枝。菌株JL1的ITS rDNA序列与GenBank基因库中水霉属菌株自然聚类,同源性高达99%,与Saprolegnia sp.H(登录号:EF460351)的亲缘关系最近。结合形态特征与ITS序列鉴定的结果,判定菌株JL1为水霉菌(Saprolegnia sp.)。此外,菌株JL1在5°C-30°C、pH 4-11范围内均能生长,最适生长温度和pH范围分别为25°C-30°C和6-9。同时菌株JL1对NaCl敏感,质量分数为2%的NaCl即可抑制其生长,可以作为该病防治的依据。
Three filamentous fungi were isolated from the diseased Pengze crucian carp eggs. One of the filamentous fungi, JL1, was confirmed to be pathogenic by artificial infection test and further studied its morphological and growth characteristics ITS rDNA sequence analysis. The results showed that the mycelium of strain JL1 was a transparent tubular structure with no transversal septum and few branches. The majority of zoospores were rod-shaped and the zoospores were arranged in multiple rows. After mature, they were released from the sporangia Quickly free; Oviduct was spherical, with the same branch or heterophoria. The ITS rDNA sequence of strain JL1 is 99% homologous to that of the strain of M. Sibiricum in GenBank, and it has the closest genetic relationship with Saprolegnia sp. H (accession number EF460351). According to the results of morphological characteristics and ITS sequence identification, strain JL1 was identified as Saprolegnia sp. In addition, strain JL1 was able to grow at 5 ° C-30 ° C and pH 4-11. The optimum growth temperature and pH range were 25 ° C-30 ° C and 6-9, respectively. At the same time strain JL1 sensitive to NaCl, 2% NaCl can inhibit its growth, can be used as the basis for the prevention and treatment of the disease.