Halophytes Increase Rhizosphere Microbial Diversity And Network Complexity In Inland Saline Ecosystem

Abstract

Background: Salinization is an important global environmental problem influencing sustainable development of terrestrial ecosystems. Salt-tolerant halophytes are often used as a promising approach to remedy the saline soils. Yet, how halophytes affect rhizosphere microbial diversity, and microbes’ association and functions in saline ecosystems remains unclear, restricting our ability to assess plant fitness to salt stress and to remediate saline ecosystems. Herein, we examined bacterial and fungal diversities, compositions, and co-occurrence networks in the rhizospheres of six halophytes and bulk soils in a semiarid inland saline ecosystem. We also established the relationship of microbial structure and network complexity to microbial functions.Results: The microbial communities in rhizospheres were more diverse and complex than those the bulk soils. The connections of taxa in the rhizosphere microbial communities increased with fungi-fungi and bacteria-fungi connections and fungal diversity, but decreased with bacteria-bacteria connections and bacterial diversity. The proportion of the fungi-related central connections were larger in the rhizospheres (13-73%) than the bulk soils (3%). Additionally, fungi accounted for 27-63% of the keystone taxa identified in the microbial co-occurrence networks present in the rhizospheres, whereas the keystone taxa identified in the bulk soils were all bacteria/archaea. Moreover, microbial activity and residues were significantly higher in the halophyte rhizospheres than the bulk soils, and were significantly correlated with microbial composition and co-occurrence network complexity.Conclusions: These results indicated that halophytes shaped rhizosphere microbiomes and increased microbial diversity and network complexity in inland saline ecosystem, while fungi enhanced rhizosphere microbiota associations. The increased microbial network complexity contributed to the higher microbial functions in rhizosphere soils.