关键词: 内生细菌, 群落特征, 环境因子

Abstract: To explore dynamics and influencing factors of endophytic bacterial community in leaves of Lycium barbarum at different growth stages, endophytic bacterial community in young, mature and old leaves of Lycium barbarum were examined using the high-throughput sequencing. Canonical correspondence analysis and variance partitioning canonical correspondence analysis were used to analyze the effects of three environmental factors on the dynamics of endophytic bacteria community, including the living conditions of host plants represented by climatic factors, the physiological status of host plant’s organs represented by photosynthesis parameters, and the endophytic bacteria living micro-environmental condition in host plants represented by nutrients that can be utilized by microorganisms. The results showed that 28 phyla, 52 classes, 118orders, 249 families, 503 genera, 738 species and 978 OTUs of endophytic bacteria were found during three growth periods. The alpha diversity and richness of OTU were the highest in the young leaves, decreased with the ages of leaves, and being at a relatively low level in mature and old leaves. The class γProteobacteria of phylum Proteobacteria dominated the endophytic bacteria in the leaves. In addition, genus Stenotrophomonas in family Xanthomonas, genus Pseudomonas in family Pseudomonadaceae, and genusPantoea in family Enterobacter were dominant in young, mature, and old leaves, respectively. The endophytic bacteria OTUs in mature and old leaves were mainly inherited from the preceding growth period. The function of endophytic bacteria changed slightly with the growth stage of leaves. The environmental factors affecting the composition of endophytic bacterial community differed across growth stages, with foliar nutrients having the greatest impact. The endophytic bacteria in leaves of Lycium barbarum responded to the changes of in vivo and in vitro environment during different growth stages based on each characteristic of endophytic bacterial community. The living micro-environmental condition of endophytic bacteria in host plants was the main factor affecting the dynamics of endophytic bacterial community in leaves of Lycium barbarum.

Key words: endophytic bacteria, community characteristics, environmental factor.