Composition and functions of soil bacterial communities of wild Glycyrrhiza uralensis Fisch. in habitats with different degrees of salinization

Abstract:

[Objective] We investigated the diversity, composition, and functions of soil bacterial communities of wild Glycyrrhiza uralensis Fisch., a typical halophyte and medicinal plant, in the habitats with different degrees of salinization. The study can help to reveal the linkage between soil salinity and microbiome related to the growth, development, and quality formation of G. uralensis, being essential for improving the quality of cultivated G. uralensis. [Methods] Soil samples were collected from six main habitats of wild G. uralensis. High-throughput sequencing was employed to compare the diversity, composition, and functions of soil bacterial communities among the habitats of un-salinization (US), light salinization (LS), moderate salinization (MS), and heavy salinization (HS) and to excavate the dominant bacteria in different habitats. [Results] The soil bacterial richness and diversity of wild G. uralensis were higher in LS and MS habitats than in US and HS habitats and were the lowest in the HS group. The principal component analysis (PCA) revealed differences in the composition and functions of soil bacterial communities between groups with different degrees of salinization (P<0.05). The redundancy analysis (RDA) showed that total salinity (TS) was an important factor influencing the composition and functions of the soil bacterial community in the native habitat. The dominant bacterial genera in the US and LS groups were the same, all of which were plant-beneficial bacteria, including Nocardioides, Streptomyces, and Marmoricola. The significantly dominant genera in the MS group included both the beneficial bacteria unidentified_Acidobacteria and the halophilic bacteria Halomonas and Marinobacter. The soil bacteria in the HS group were dominated by salinophilic or salinity-tolerant bacteria, including Halomonas, Marinobacter, Truepera, Alifodinibius, Salinimicrobium, and Salegentibacter. The PICRUSt prediction results underlined the potential of soil bacteria in interactions with plants in US, LS, and MS groups, suggesting that beneficial bacteria in the three habitats influenced the growth, development, and quality formation of wild G. uralensis. Moreover, the prediction results emphasized that the soil bacteria endowed the HS group with the potential of self-repairing for adaptation to highly saline environments and improving the salt tolerance of wild G. uralensis. This result suggested that halophilic and salt-tolerant bacteria in the HS habitat played a key role in the salt tolerance of wild G. uralensis. The MS habitat had both kinds of bacteria, being worthy of attention. [Conclusion] The soil bacterial diversity and richness of wild G. uralensis were remarkably higher in LS and MS habitats than in US and HS habitats. The composition and functions of soil bacterial communities in US and LS habitats were similar and differed significantly from those of the HS habitat, and the MS habitat had characteristics of both the above.