Effects of hydrogen sulfide on the structures of phyllosphere and rhizosphere microbial communities of soybean plants under drought stress

Abstract:

[Objective] To investigate the effects of hydrogen sulfide (H₂S) on the structures of phyllosphere and rhizosphere microbial communities of soybean plants under drought stress. [Methods] High-throughput sequencing of the 16S rRNA gene was combined with bioinformatics analyses (α and β diversity, species composition, co-occurrence networks analysis, etc.) to study the phyllosphere and rhizosphere microbial communities of soybean plants before and after NaHS treatment. [Results] For the soybean plants under normal moisture conditions, the addition of NaHS decreased the diversity and increased the endemic species of phyllosphere microbial community. The addition of NaHS increased the diversity of rhizosphere microbial community of soybean plants under normal moisture conditions but not under severe drought. In addition, exogenous addition of NaHS altered the bacterial co-occurrence network, and the microbial communities in both phyllosphere and rhizosphere were so aggregated that neither rhizobium inoculation nor NaHS addition had significant influences on them. The addition of NaHS mildly affected the relative abundance of operational taxonomic unit (OTU) in the phyllosphere and decreased the relative abundance of OTU in the rhizosphere, which was particularly pronounced under severe drought. Rhizobium inoculation and NaHS addition enriched different microbial taxa in both phyllosphere and rhizosphere. [Conclusion] Under drought stress, H₂S had an insignificant modulating effect on the microbial community structure in the phyllosphere but a pronounced effect on the microbial community structure in the rhizosphere of soybean plants. H₂S reduced the relative abundance of total OTU in the rhizosphere and altered the bacterial co-occurrence network, thus influencing soybean adaptation to drought stress.