In this paper traditional bacterial isolation and culture techniques,combined with 16S rDNA sequence analysis,were used to investigate diversity of community structure and seasonal dynamics of endophytic bacteria in cortex tissues of Populus tomentosa and P.× euramericana cv.Robusta 94.A total of 532 isolates were obtained from the two poplars and their 16S rDNAs were sequenced and analyzed.Results showed that the isolates were classified into 26 genera and 47 species.There was difference in the isolate composition between two poplars.The number of bacteria genera and species isolated from P.tomentosa and P.× euramericana cv.Robusta 94 was much different.There were 18 genera and 30 species isolated from P.tomentosa,and Rhizobium and Bacillus were the most predominant,while there were 16 genera and 22 species from P.× euramericana cv.Robusta 94,Rhizobium and Microbacterium were the most widely distributed and predominant.The results indicated that the community structure of plant endophytic bacteria was diverse in the poplars.The seasonal variation in the number of bacterial isolates from the two poplars exhibited that endophytic bacteria isolated in summer and autumn were more than in winter and spring.The dominant species of the bacterial communities changed significantly with the seasonal fluctuation.%为了解三倍体毛白杨和健杨94树干皮层组织中内生细菌的群落多样性和季节动态变化,利用传统的细菌分离培养,结合16S rDNA序列分析等方法对其进行分析.从2种杨树干部皮层中共计分离纯化细菌菌株5 32株,分属于26属47种,2种杨树内生细菌组成存在较大差异.其中,从三倍体毛白杨中分离得到1 8属30个种,以根瘤菌属和芽孢杆菌属为优势菌群；健杨94中分离得到16属22个种,以根瘤菌属、微杆菌属为优势菌群.杨树干部皮层植物内生细菌的多样性丰富.2种杨树内生细菌数量季节变化规律总体表现为夏秋2季均高于冬春2季.2种杨树在4个季节的优势菌群各不相同,随季节变化而变化.
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