Molecular Diversity and Functional Prediction of Foliar Endophytic Bacteria in Tectona grandis (Teak) Estimated by 16S rDNA Sequence Analysis

Abstract

The multi-layer structure of leaves supports endophyte colonization facilitating compatible plant-microbe interactions. Endophytic microbiota, including bacteria, influence the vital activities of plants. Yet, information on bacterial communities in leaves of forest trees largely remains unknown. This study describes the bacterial endophytes observed in Tectona grandis (Teak) identified by high-throughput sequencing of 16S rDNA sequences. The paper also provides details on the functional prediction of the bacterial community. Nine teak samples sequenced with 98% genome coverage provided 24,833–42,892 bacterial sequence reads, which aligned to 2827 operational taxonomic units (OTUs) of the V3–V4 conserved region with more than 97% sequence identity. Shannon Index ranged from 4.56–5.02 revealing high bacterial diversity. We identified 21 phyla, 39 classes, 65 orders, 226 families, and 127 genera. The phyla in abundance were Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. The identified genera include Lactobacillus (12.12%), Prevotella (9.78%), and Bacteroides (9.68%) and the category under unclassified genus constituted for 65.8% providing opportunities for identification of new species. The functions of the genes were studied using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis. It revealed the possible involvement of the bacteria in various metabolic processes with top-most functions related to transporters, DNA repair and recombination proteins, and the ribosome. Further studies on these gene interactions would help to understand the potential of bacterial endophytes in promoting growth and conferring protection.