Dynamic changes in rhizosphere bacterial communities of Rhododendron simsii at different growth stages

Abstract

Rhododendron simsii plays important roles in maintaining ecological system stability in the north temperate zone. However, its natural growth is greatly affected by soil microorganisms, particularly rhizosphere microbes. In this study, a comparative analysis was conducted of the bacterial community structure in the rhizosphere of R. simsii at the old, adult, juvenile, and seedlings stages. The results showed that Proteobacteria (38.53%‒47.63%), Actinobacteria (23.45%‒34.03%), and Acidobacteria (10.33%‒17.79%) were the dominant phyla in the R. simsii rhizosphere. In particular, 3, 5, 42, and 33 OTUs were unique to the soil samples of ‘old trees’, ‘adult trees’, ‘juvenile trees’, and ‘seedlings’, respectively. Across four sets of R. simsii rhizosphere microbes sampled from seedlings to old trees, the OTUs first increased, then decreased, and finally increased. Overall, alpha diversity (Chao, ACE, and Sobs) revealed similar trends with the highest value i‒n recorded for the rhizosphere sample of ‘adult trees’ and the lowest for the ‘seedlings’ sample. The bacterial genera in the rhizosphere samples from ‘old trees’ and ‘adult trees’ exhibited close clustering. Notably, the R. simsii population of ‘juvenile trees’, demonstrating the highest genetic diversity, were rich in Bradyrhizobium and Streptomycetes. This research serves to benefit the domestication of wild R. simsii and other Rhododendron resources.

Keywords

• bacterial populations
• community structure
• high-throughput sequencing
• rhizosphere
• rhododendron species