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

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.