The Root Nodule Microbiome of Cultivated and Wild Halophytic Legumes Showed Similar Diversity but Distinct Community Structure in Yellow River Delta Saline Soils

Symbiotic associations between leguminous plants and their nodule microbiome play a key role in sustainable agriculture by facilitating the fixation of atmospheric nitrogen and enhancing plant stress resistance. This study aimed to decipher the root nodule microbiome of two halophytic legumes, and , which grow in saline soils of the Yellow River Delta, China, using PacBio's circular consensus sequencing for full-length bacterial 16S rRNA gene to obtain finer taxonomic information. The cultivated legume was used for comparison. We identified 18 bacterial genera and 55 species in nodule samples, which mainly classified to , and rhizobial genus was the predominant group. The three legumes showed similarity in operational taxonomic unit (OTU) diversity but distinction in OTU richness, indicating that they harbor similar bacterial species with different relative contents. The results of principal coordinates analysis and ANOSIM tests indicated that and have similar nodule bacterial communities, and these communities differ from that of . Wild legumes and both harbored a higher number of rhizobia, while possessed more non-rhizobial bacteria. These differences could be associated with their adaptability to saline-alkali stress and revealed clues on the nodule endophytes with relative importance of culturable rhizobial symbionts.