Diversity and Predictive Functional of Caragana jubata Bacterial Community in Rhizosphere and Non-rhizosphere Soil at Different Altitudes

Abstract

Caragana jubata, as the main dominant plant in the alpine and subalpine regions of northern China, is an important component of the local ecosystem. However, few studies have paid attention to its impact on the soil ecosystem and its response to environmental changes. Thus, in this study, we used high-throughput sequencing technology to investigate diversity and predictive function of rhizosphere and bulk soil bacteria communities of C.jubata from different altitudes. The results indicated that 43 phyla, 112 classes, 251 orders, 324 families, and 542 genera were obtained from the soil. The dominant phyla in all sample sites were Proteobacteria, Acidobacteria, and Actinobacteria. There were significant differences in bacterial diversity index and community structure between the rhizosphere and bulk soil at the same altitude, whereas the differences across altitudes were insignificant. PICRUSt analysis showed that the functional gene families were mainly related to 29 sub-functions, including amino acid metabolism, carbohydrate metabolism, and metabolism of cofactors and vitamins, and the abundance of metabolism was highest. There were significant correlations between the relative abundances of genes involved in the level Ⅱ metabolic pathway of bacteria and phylum-level taxa, such as Proteobacteria, Acidobacteria, and Chloroflexi. The predicted functional compositions of soil bacteria also showed a significantly positive correlation with the dissimilarity in bacterial community structure, indicating that there was a strong relationship between bacterial community structure and functional genes. This study preliminarily discussed the characteristics and functional prediction analysis of bacterial communities in the rhizosphere and bulk soil of C.jubata at different altitudinal gradients, which provided data support for the ecological effects of constructive plants and their responses to environmental changes in high altitude areas.