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首次应用通用引物ITS1与 ITS4从杨树叶枯病菌中扩增出目的片段为601bp 的rDNA ITS序列(登录号为DQ011257).与GenBank核酸序列数据库进行比对表明:本菌株与Alternaria alternata(AY787684)及Alternaria alternate(AY354228) 相似率为98%,验证为Alternaria alternate.杨树叶枯病菌生物学特性如下:分生孢子萌发最适温度25℃,最适pH为6.菌丝生长最适温度为25℃,在10℃与30℃时生长极其缓慢,高于35℃时,生长停止;菌丝生长最适pH 为6,在PDA+杨树煎汁培养基上生长最好.图5表4参11.“,”DNA was extracted from the strain of pathogen of poplar leaf blight using a modified CTAB method. ITS sequence (601bp) was initially amplified from the pathogen by using the universal primers ITS1 and ITS4 (registered No. DQ011257). Comparing to the nucleotide sequences acquired from GenBank database, the strain is clustered into the homogeneity with Alternaria alternate (AY787684) and Alternaria alternate (AY354228), with a homology of 98%, thus the strain was checked as Alternaria alternata (Fr.) Keissler. The optimal conditions for conidia germination and mycelium growth of the pathogen were tested. The optimal temperature for conidia germinating and mycelium growth is 25oC, and the optimal pH value is 6. Mycelium grows rather slowly at 10 oC and 30 oC and growth stops at above 35 oC. Among the six culture mediums tested, PDA + poplar leaf juice medium is most favorable for mycelium growth.