Structure and composition variation of the root-microbiota of Rhododendron delavayi

Abstract:

[Objective] The aim of this study was to understand the structure variation and assembly of root-microbiota of wild Rhododendron delavay. The spatial resolution of the study distinguished three niches of Rhododendron delavayi root, the endosphere, rhizoplane, and rhizosphere. Here we compared the microbial community structure and composition variation between the three niches. [Methods] A detailed characterization of the root-microbiota of the Rhododendron delavayi by deep sequencing, using 16S rRNA V4 and ITS1 regions of microorganisms. The diversity and composition of microbial community from three niches were compared. In addition, we discussed the relationship between differential microbial genera based on co-occurrence network.[Results] In the constrained unconstrained principal coordinate analyses of Bray-Curtis distances between samples, microbial communities vary significantly between three niches. Moreover, the separation of root-microbiota from rhizosphere to rhizoplane is larger. The bacterial α-diversity between three niches is considered as statistically significant difference. 41 bacterial phyla and 6 fungal phyla abundance in the root-microbiota. The dominant bacterial phyla included Proteobacteria, Acidobacteria and Actinobacteria, which occupied more than 80% of the total abundance of bacterial communities. The dominant fungal phyla included Zygomycota, Basidiomycota and Ascomycota, which account for more than 99% of the total abundance of fungal communities. 589 bacterial genera and 390 fungal genera abundance in the root-microbiota. Moreover, the abundance of 25 bacterial and 10 fungal genera varied between three niches. Furthermore, analyzing the co-occurrence network of the differential genera showed the interaction between fungi and bacteria in the root-microbiota. Eight differential fungi was significantly correlated to differential bacteria, except Waitea. As the core genera in the co-occurrence network, Bryobacter, Nocardia, Rhizomicrobium and Telmatobacter played a very important regulation.[Conclusion] Dynamic changes observed during root-microbiota, as well as compositions of three niches, support a hypothesis for root microbiome assembly correlated with the root. At the same time, co-occurrence network analysis revealed bacteria and fungi interacted with each other among the three niches.