Interaction between rhizobacterial community and host root determines poplar salt tolerance

Abstract Rhizosphere microbes play important roles in plant tolerance to abiotic stresses. Plants of different genetic backgrounds acquire stress resistance by assembling specific rhizosphere microbial communities or typical beneficial microbiota. However, the molecular mechanisms by which plants recruit microbiota during plant acclimation to environmental stresses are unclear. Here, we investigated transcription pattern in three poplar genotypes, namely Populus davidiana × P. bolleana Loucne (SXY), P. deltoides × P. euramericana ‘Nanlin 895’ (NL895) and P. alba × P. glandulosa ‘84K’ (84K), and their effect on the rhizosphere microbial community under salinity. The results showed that SXY exhibited salt tolerance characterized by the best performance of photosynthesis and antioxidant system upon salt stress, while salt stress severely damaged the growth and membrane system of 84K. 16S rRNA sequencing revealed the lowest rhizobacterial community diversity associated with SXY compared to 84K and NL895, implying strong enrichment of certain bacterial taxa by the salt tolerant cultivar. Specifically, SXY recruited higher abundances of Hydrogenophaga and Pseudomonas . Furthermore, RNA‐seq analysis of roots combined with weighted gene co‐expression network analysis (WGCNA) identified module eigengene (ME)yellow, a module positively correlated to the SXY‐enriched OTUs. KEGG analysis revealed significant enrichment of lipid metabolic and amino acid biosynthetic pathways in MEyellow. Twenty‐four genes selected from the pathways enriched in MEyellow showed the highest expression levels in SXY. Our results suggest a “gene expression‐rhizosphere‐microbiota‐salt tolerance” regulatory process in the poplar under salinity and provide new insights into the mechanisms by which plants shape the soil microbiome to improve salt tolerance.