Composition and diversity of root-inhabiting bacterial microbiota in the perennial sweet sorghum cultivar at the maturing stage

The bacterial microbiota inhabiting the endosphere and rhizoplane regulate plant growth. The mutualistic interaction between sweet sorghum and soil bacteria has drawn increasing research attention. Nevertheless, the root-inhabiting bacterial microbiota of sweet sorghum’s perennial analog have rarely been characterized. Here, the root-inhabiting bacterial microbiota of the perennial sweet sorghum cultivar NaPBS778 (N778 simply) and its control TP60 were discovered at the flowering and maturing stages under field growth by high-throughput amplicon sequencing of the 16S rRNA gene via Illumina MiSeq. Nearly all alpha diversity indices of aerial and primary root samples of N778 were not significantly distinct from those of TP60 at the maturing stage, except for the observed species (Sobs) and phylogenetic diversity indices. The beta diversity of aerial and primary root samples showed no significant differences between N778 and its control TP60 at the maturing stage. Moreover, the bacterial microbiota in N778 aerial and primary roots was not only predominated by Proteobacteria, Actinobacteria, and Bacteroidetes at the phylum level but also strikingly distinct from the bacterial microbiota in rhizosphere soil at the genus level. Additionally, the root samples of N778 at the maturing stage were considerably enriched with OTU1262 being a potential cold-adapted bacterium belonging to Pseudarthrobacter , OTU434 plus OTU1304 belonging to Streptomyces and associated with crop nitrogen stress-tolerance, and OTU836 belonging to the family Oxalobacteraceae and potentially promoting crop growth. Our findings suggest that the perennial sweet sorghum cultivar N778 may recruit potentially cold-tolerant, plant growth-promoting, and nitrogen stress-tolerant bacterial taxa into roots at the maturing stage.