The effect of plant growth-promoting bacteria application on rhizospheric microbial community and cadmium related regulatory network of Chrysopogon zizanioides in mining soil

AimsPlant growth-promoting bacteria (PGPB) associated with hyperaccumulator plant species have been widely proposed to remediate metal contaminated mining soil, while the impacts of PGPB on rhizospheric bacterial communities, and the interaction mechanisms of PGPB and hyperaccumulators are little known. Here, this study investigated the response of rhizospheric microbial community and the cadmium (Cd) related regulatory network in Chrysopogon zizanioides with the application of Serratia marcescens SNB6 in mining soil.MethodsThe bacterial diversity and community in rhizospheric soil were analyzed by the 16S RNA sequencing. The roots of C. zizanioides were analyzed using transcriptome sequencing.ResultsThe colonization of SNB6 in rhizospheric soil significantly (P < 0.05) increased the Cd accumulation in C. zizanioides roots by 13.75%, and enhanced the rhizospheric bacterial diversity. The up-regulated genes related to cell wall biosynthesis and antioxidation system were enriched in the Cd treatment. However, The up-regulated genes connected to transporter activity were enriched in the Cd_SNB6 treatment, which participating in Cd efflux such as ABC transporter were down-regulated, whereas Nramp5 responsible for Cd transport was markedly up-regulated.ConclusionThe colonization of SNB6 enhanced the rhizospheric bacterial diversity. The expression of cell wall biosynthesis coding-genes and antioxidant coding-genes was up-regulated to reduce the toxicity of Cd, while the inoculation of SNB6 activated the expression of Nramp5, thus enhancing the Cd fixation in root cells. Our study could provide theoretical basis for the industry practice of SNB6 in the phytoremediaiton. These findings, however, need to be verified under field conditions in the further studies.