Root-inhabiting bacterial microbiota of the perennial sweet sorghum cultivar at the maturing stage under cold stress

Abstract The bacterial microbiota inhabiting the endosphere and rhizoplane play numerous important functions in improving plant growth. The mutualistic interaction between sweet sorghum and soil bacteria has drawn increasing attention. However, the bacterial microbiota inhabiting the roots 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. Almost all alpha diversity indices of aerial and primary root samples of N778 were not significantly different from those of TP60 at the maturing stage, except for the observed species (Sobs) and phylogenetic diversity indices. Next, 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 was 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, OTU434, OTU1304, and OTU836, which belonged to the genera Pseudarthrobacter, Streptomyces, and an unclassified genus of the family Oxalobacteraceae, respectively. Our findings imply that the perennial sweet sorghum cultivar N778 may recruit not only potentially cold-tolerant but also plant growth-promoting and nitrogen stress-tolerant bacterial taxa into roots at the maturing stage.