不同生长季节黑果枸杞的根际细菌群落结构

The rhizosphere bacterial community dynamics of the halophyte Lycium ruthenicum in different growth stages

摘要:

[目的]黑果枸杞是一种耐盐植物，是我国西北干旱区盐渍土改良的优良植物物种，其根际土壤细菌群落结构在不同生长时期的变化特征尚不清楚。[方法]本研究采用Illumina MiSeq高通量测序研究了黑果枸杞3个生长阶段的根际土壤细菌群落结构的动态变化。[结果]所有样品中共获得317467条序列，对应于7028个细菌/古细菌OTUs。根际土壤细菌群落的α多样性显著高于非根际土壤。衰老期根际细菌的多样性和丰富度明显低于营养生长期和花/果期。变形菌门和酸杆菌门的相对丰度随生长时期的演变而逐渐降低，而蓝细菌门则相反。厚壁菌门的丰度在衰老期明显高于营养生长期和花/果期。优势属的组成也随生长期的演变而改变，营养生长期、花/果期、衰老期的优势属数量分别为17、16、4，且组成也具有差异。相似性分析表明营养生长期和花/果期的根际细菌群落具有很高的相似性，衰老期根际细菌群落组成与生长期和花/果期具有很高差异，然而与非根际土壤的群落结构具有较高的相似性。[结论]根际土壤细菌群落多样性和组成随生长期的改变而表现出明显的动态变异性，表明黑果枸杞生长时期对根际土壤细菌群落结构具有重要的影响。

关键词:盐生植物;根际土壤;细菌群落;生长阶段动态

Abstract:

[Objective] Lycium ruthenicum is a halophyte and used to improve saline lands in northwest China. However, little is known about the bacterial community structural dynamics with growth stage.[Methods] We investigated the dynamics of rhizosphere bacterial community structure in three growth stages using Illumina MiSeq high-throughput sequencing. [Results] We obtained a total of 317467 16S rDNA reads, corresponding to 7028 bacterial/archaeal operational taxonomic units. The alpha diversity was higher in the rhizosphere than in bulk soil. The diversity and richness of rhizosphere bacteria were much lower in senescence stage than that in vegetative and flowering/fruiting stages. The relative abundances of Proteobacteria and Acidobacteria gradually decreased, whereas the abundance of Cyanobacteria increased along with growth cycle. The phylum Firmicutes abundance was significantly higher in senescence stage than in other stages. The abundant genera composition also changed with growth stage. Seventeen genera (i.e. Corynebacterium, Acidovorax, Elizabethkingia, Albirhodobacter and Pseudomonas) were abundant at vegetative stage; Sixteen bacterial genera were enriched in flowering/fruiting stage, including Rhodoligotrophos, Geminicoccus, Gracilimonas and Thioprofundum. Four bacterial genera, Exiguobacterium, Citrobacter, Acinetobacter and Pseudomonas, were abundant in senescence stage. In vegetative and flowering/fruiting stages, the rhizosphere bacterial community was of high similarity, and the similarities between rhizosphere communities were higher than that between rhizosphere and bulk soil communities. However, in senescence stage, the rhizosphere bacterial community composition was more different from the communities in previous stages, but turned to be more similar with that of bulk soil. [Conclusion] The rhizosphere bacterial community diversity and composition were changing with growth stage, and great difference was found between senescence stage and previous two stages. Plant growth stage had important effects on structuring the rhizosphere bacterial community of L. ruthenicum.

Key words:halophyte;rhizosphere soil;bacterial community;growth stage dynamics