Spatial Niche Differentiation and Growth-Promoting Functions of Bacterial Microbiota in Smilax china L

An extremely crucial role is exerted by bacteria in plant growth and development. To investigate the specific distribution patterns of bacteria from control check soil (CK) to rhizosphere soil (RS), plant roots (R), stems (T) and leaves (L), as well as their effects on plant growth and development, Smilax china L. with typical rhizomes was selected as the research material in this study. Samples of CK, RS, R, T and L were collected from 10 sampling sites of plants that had been transplanted and established for 3 years. On the basis of determining the conventional physicochemical properties and culturable microbial contents of the soil, the V5-V7 regions of the bacterial 16S rRNA gene were amplified from the total DNA of each sample, followed by high-throughput sequencing. Subsequently, bioinformatics analysis was conducted using QIIME2. Results : Significant differences were observed in the changes of soil physicochemical properties and culturable microorganisms induced by the growth of S. china L. The highest species richness and α-diversity level were detected in RS, whereas more dominant taxa were identified in R. The community composition was stable in each spatial niche, and the taxa with high abundance in T and L were basically consistent with the dominant taxa. The top 10 genera mainly played the role of "connectors" in the entire network system, and no obvious network core taxa or peripheral taxa were found in the system. The endophytes in the above-ground parts of S. china L. supplemented nutrients for the plant through metabolism. The endophytes in rhizomes degraded harmful substances via metabolic processes and produced certain plant growth regulators to promote cell division. Conclusion : The growth of S. china L. causes changes in soil physicochemical properties, which in turn induce alterations in the spatial distribution of bacterial communities. These changes enable endophytic bacteria in the plant to supplement nutrients for different plant parts and degrade harmful components through metabolism, thereby enhancing the plant's competitiveness in diverse environments. In addition, some endophytes produce growth regulators to promote cell division, which may be one of the reasons for rhizome enlargement and the improvement of its commercial value.