Effect of tree age on community diversity of the endophytic and rhizospheric bacteria in Catalpa bungei.

Catalpa bungei is one of important economic tree species for widespread cultivation in China, but little is known about the endophytic and rhizospheric bacteria especially how tree age affects their community diversity. The research assessed tree ages of 2, 4, 8, and 12 years, respectively, affect the community diversity of endophytic and rhizospheric bacteria in C. bungei using high-throughput 16S rRNA gene sequencing. Findings revealed that the diversity and abundance of rhizospheric bacteria were significantly higher than that of endophytic bacteria, and both endophytic and rhizospheric bacterial flora, especially the dominant bacteria, showed a certain degree of regular variations with the tree age increasing. The dominant endophytic and rhizospheric bacteria were Cyanobacteria and Proteobacteria, respectively, at a phylum level, which were Streptophyta, Acidobacterium or Flavobacterium at a genus level. Correspondingly, photophosphorylation was a dominant ecological function for the endophytic bacteria, while chemoheterotrophy and aerobic chemoheterotrophy were important ecological functions for the rhizospheric bacteria. This study highlights dynamic changes in the endophytic and rhizospheric bacterial communities of C. bungei and provides references for the follow-up development of agricultural inputs.