Seasonal variations and assembly patterns of endophytic communities of Rheum palmatum.

The endophytes are closely associated with the growth and development, stress resistance and active ingredients synthesis of medicinal plants. However, seasonal succession and assembly process of endophyte is still unclear. In this study, we used amplicon sequencing to analyze seasonal succession and the assembly processes of endophyte of Rheum palmatum under different season, and the driving factors of community differences were explored. The results show that the diversity and connectivity and complexity of co-occurrence network of endophytic communities were affected by seasonality, Proteobacteria and Ascomycota were the dominant endophytic phyla, dominant fungal genus of various tissues existed differences, while Delftia were dominant bacterial genus of various tissues under different season. Mantel analysis indicated that the influence of environmental factors on the differences of endophytic community differ under different seasons. Null model and neutral community model showed that the assembly process of endophytic communities was dominated by deterministic process under different seasons. Source tracker analysis found that the sources of endophytes of varous tissues existed differences under different seasons. These results illustrate the clear season heterogeneity of endophytic communities and provide new insights into revealing the effects of seasonal succession on endophytic assembly processes of medicinal plant.