硫化氢对水分逆境胁迫下大豆叶际和根内微生物群落结构的影响

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

摘要:

【目的】 研究硫化氢(hydrogen sulfide, H2S)对水分逆境胁迫下大豆叶际和根内微生物群落结构的影响。【方法】 利用16S rRNA基因进行高通量测序，并结合生物信息学分析(α多样性、β多样性、物种组成、共现网络分析等)对NaHS处理前后大豆叶际和根内微生物群落进行分析。【结果】 在大豆正常水分情况下，NaHS的添加会降低叶际微生物生境内的多样性，增加其特有物种，并提高根内微生物的多样性，但在重度干旱下NaHS的添加并未表现出类似的效应。此外，外源添加NaHS会改变细菌共现网络属性，由于叶际和根内区域的微生物群落的聚集度都很高，接种根瘤菌和添加NaHS对其无显著影响。NaHS的添加对叶际操作分类单元(operational taxonomic unit, OTU)的相对丰度影响较小，但是导致了根内OTU的相对丰度减少，而在重度干旱下，这种现象尤为明显。无论是在叶际区域还是在根内区域，不同的微生物类群在接种根瘤菌和添加NaHS下均得到了富集。【结论】 在水分逆境胁迫下，H₂S的调控对大豆叶际微生物群落结构影响不明显，但是对根内微生物群落结构的影响较为明显，通过改变细菌共现网络属性，降低根内总OTU的相对丰度，进而影响大豆对水分逆境环境的适应性。

关键词:硫化氢;逆境胁迫;高通量测序;微生物群落结构

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.

Key words:hydrogen sulfide;stress;high-throughput sequencing;microbial community structure