黄河三角洲盐碱地花生根层土壤菌群结构多样性

花生属豆科固氮作物,具较强的抗旱耐盐性,土壤微生物在盐碱土生态系统中具有重要的生态功能。以花生平作、花生/棉花间作为对象,通过16S rRNA基因克隆文库技术分析了黄河三角洲滨海盐碱地花生旺盛生长期不同含盐量盐碱地和非盐碱地0—40cm根层非培养土壤微生物群落组成及其多样性,分析了盐碱地花生根层土壤细菌群落与非盐碱地花生根层土壤细菌群落的差异,为揭示盐碱地花生根层土壤微生物的多样性以及土地利用变化与生态环境效应间的关系奠定基础。利用免培养技术直接从土壤样品提取总DNA,针对细菌基因组16S rRNA基因的V3高变区进行PCR扩增;利用焦磷酸测序的方法对V3高变区PCR产物进行高通量测序,并对测序数据进行生物信息学分析。结果表明,(1)黄河三角洲滨海盐碱土较高含盐量土壤中根层土壤微生物种类、优势种群数量和群落功能多样性较非盐碱土壤较为丰富。(2)盐碱土花生平作或花生//棉花间作两种种植方式基本不影响二者0—40cm根层土壤微生物优势类群;不同土壤类型和种植模式下,花生和棉花根层土壤中优势菌群均为变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、绿弯菌门(Chloroflexi)和酸杆菌门(Acidobacteria) 4种菌群,其总丰度为80%—90%。非盐碱土壤中花生根层的酸杆菌门(Acidobacteria)丰度是盐碱土壤中的3倍以上,嗜热油菌纲(Thermoleophilia)和放线菌纲(Actinomycetales)丰度远高于各种盐碱土壤花生平作和花生//棉花间作两种植模式下的花生根层土壤;非盐碱土平作花生0—40cm土层中Rubellimicrobium、Pontibacter和Lamia细菌则显著缺失。(3)土壤类型对土壤微生物菌群类型影响较大,聚类分析表明,10个土壤样本依据土壤含盐量高低和根系分布深度聚为3类,即非盐碱土壤归为1类,盐碱土壤根系密集分布层0—20cm、20—40cm各归为1类。

Comparison of the microbial community in the rhizosphere of peanuts between saline-alkali and non-saline soil at different soil depths and intercropping cultivation in the Yellow River Delta

The peanut or groundnut (Arachis hypogaea L.) is an important nitrogen fixing legume worldwide, which is strongly drought and salt resistant. Soil microbiomes play an important ecological role in the saline-alkaline soil ecosystem. Many factors could shape the rhizosphere microbiome, but the effects of soil salinity, intercropping patterns, and soil depth on the composition of bacterial communities for peanuts are largely unknown. In this study, to compare and analyze the difference in rhizosphere bacterial communities between saline-alkali and non-saline soil, the soil in which the peanuts were grown, under single cropping and intercropping, were used as experimental materials. The different soil bacterial community compositions and diversities from 0-40 cm soil of saline-alkali and non-saline land in the saline-alkali coastal areas of the Yellow River Delta were analyzed using 16S rRNA gene clone library technology. Thus, our study has laid a solid foundation for further functional investigation into the diversity of soil rhizosphere microbiomes from different soil types and the relationship between land use change and ecological environmental effects. The total DNA was extracted from the soil samples using free culture technology, and PCR amplification was performed on the high variation area of V3 in the 16S rRNA gene of the bacterial genome. Pyrosequencing was used to analyze the high variation area of V3, and a bioinformatics analysis was performed to further analyze the sequencing data. All analyzed samples were characterized by diverse bacterial communities, and the relative proportions of phylum, family, and genus. The results showed:(1) Rhizospheres grown in saline-alkali soils contained more bacterial diversity, dominant species, and community functional diversity than non-saline grown ones. (2) Single cropping or intercropping patterns appeared to not affect the dominant bacterial communities in the 0-40 cm rhizosphere soil. Proteobacteria, Actinobacteria, Chloroflexi, and Acidobacteria were significantly abundant rhizosphere microbiomes in all soil types, and accounted for more than 80%-90% of the community. In addition, the abundance of Acidobacteria in non-saline soils were more than three times of these in saline-alkali land, and Thermoleophilia and Actinomycetales were more abundant in non-saline soil than those in single cropping and intercropping of saline-alkali land. However, Rubellimicrobium, Pontibacter, and Lamia were relatively less in the 0-40 cm soil of signaling cropping non-saline land. (3) Soil types appeared to affect the types of microbiomes in the rhizospheres. All the samples were largely divided into three classes:non-saline land, 0-20 cm, and 20-40 cm rhizospheres according to the soil salinity and depth of root distribution by clustering analysis.