Phylogenetic Diversity of Endophytic Bacteria Communities from marama bean Tylosema esculentum (Burchell.) A. Schreiber

Abstract

Tylosema esculentum is a nutritious drought-avoiding and climate change contender plant for future agriculture. It is endemic to the Kalahari Desert. This study assessed the density, diversity and distribution of endophytic microbial community structures associated with leaves, stems and tuberous roots of T. esculentum in Eastern Namibia using culture-dependent methods. Analysis of
Variance with pairwise comparison revealed differences in bacterial density between below and above ground. Endophytic bacterial isolates were identified and grouped into 24 genera and three phyla. Proteobacteria were the most represented (67.4%) followed by Firmicutes (23.7%) and Actinobacteria (4.3%). Shannon diversity index revealed a significant difference between the tuberous roots and
leaves (p = 0.005) and stems (p = 0.006) microbial communities. The PCA confirmed these findings. Our results suggested that the microbial community composition was mainly governed by the plant parts rather than the location or sampling time. The 16S rDNA based phylogenetic analysis showed that all these microbial communities fell into two clades distinct from known cultivated bacteria from NCBI. Our sequences have shown similarities with the ones occurring in water-stressed environments with plant growth promoting traits. In conclusion, T. esculentum bean lives in community with a large diversity of potentially plant growth-promoting bacteria