蒙古沙冬青根际土壤细菌群落组成及多样性与生态因子相关性研究

蒙古沙冬青（Ammopiptanthus mongolicus）是中国西北荒漠唯一的常绿阔叶灌木，耐干旱、抗逆性强，在水土和荒漠化防治方面发挥着重要作用。为了探究蒙古沙冬青根际微生物多样性与生态因子互作机制，采用高通量测序技术测定了26个自然种群根际土壤细菌多样性；利用冗余分析（Redundancy analysis，RDA）探讨了根际细菌群落组成和多样性与生态因子之间的关系。结果表明：蒙古沙冬青根际土壤细菌隶属于15门、43纲、68目、123科、185属；主要优势细菌群为蓝菌门（Cyanobacteria）65.74%、变形菌门（Proteobacteria）21.72%、放线菌门（Actinobacteria）6.28%（相对丰度>2%）；优势菌纲为α-变形菌纲（Alphaproteobacteria）17.48%、放线菌纲（Actinobacteria）4.76%、γ-变形菌纲（Gammaproteobacteria）3.28%。RDA分析显示：生态因子能够解释蒙古沙冬青根际土壤细菌群落多样性52.69%的方差，其中年均降雨量（F=12.8，P=0.002）、纬度（F=5.1，P=0.016）、太阳辐射（F=5，P=0.02）是影响土壤细菌多样性的主要因素。研究结果可为深入认识荒漠生态系统中根际土壤细菌的群落结构和影响因素提供理论依据。

Correlations between the composition and diversity of bacterial communities and ecological factors in the rhizosphere of Ammopiptanthus mongolicus

Ammopiptanthus mongolicus is the unique evergreen broad-leaved shrub in the desert of northwest China. It is drought tolerant, strong resistance and plays an important role in soil and water conservation and desertification control. In order to investigate the rhizospheric microbial diversity of A. mongolicus and interaction mechanism with ecological factors, the bacterial diversity of rhizosphere soil of 26 populations was determined by high-throughput sequencing technology. Redundancy analysis (RDA) was applied to analyze the correlation between rhizosphere bacterial community diversity and ecological factors. The results showed that 15 phylum, 43 classes, 68 orders, 123 families and 185 genera were detected in the 78 rhizosphere soil samples. The main dominant bacteria phylum in all sample sites were Cyanobacteria(65.74%), Proteobacteria(21.72%), Actinobacteria(6.28%) (relative abundance>2%). The dominant bacteria class were Alphaproteobacteria(17.48%), Actinobacteria(4.76%) and Gammaproteobacteria(3.28%). RDA indicated that 52.69% rhizosphere bacterial community diversity variation of A.mongolicus could be explained by environmental variables. Among factors, annual rainfall (F=12.8, P=0.002), latitude (F=5.1, P=0.016), and solar radiation (F=5, P=0.02) were the main influencing factors for dominant bacteria in rhizosphere soil of in A.mongolicus. The results of this study provided a theoretica basis for further understanding the community structure and affecting factors of rhizospheric soil bacteria in desert ecosystems.