Abstract: We investigated the effects of Ulva prolifera outbreak on growth characteristics of Suaeda salsa in Weihai, Shandong during the extinction period of U. prolifera in October 2019. We analyzed diversity of phosphate-solubilizing bacteria community in rhizosphere soil of S. salsa by Illumina Miseq high-throughput sequencing. The results showed that after the outbreak of U. prolifera, water content and electrical conductivity of S. salsa rhizosphere soil covered by U. prolifera were significantly higher than those of uncovered by U. prolifera. Plant height and root length of S. salsa covered by U. prolifera were significantly lower than those of uncovered. The outbreak of U. prolifera did not affect richness of phosphate-solubilizing bacteria community of S. salsa rhizosphere, but affected its evenness and increased the community diversity. Compared with normally growing S. salsa, the abundance of phosphate-solubilizing bacteria including Proteobacteria, Actinobacteria, Labrenzia, Mesorhizobium, Pseudomonas, Rhodobacter,Xanthomonas and Streptomyces were all different in the rhizosphere soil of S. salsa covered by U. prolifera. Available potassium, available phosphate and alkali-hydrolyzed nitrogen were significantly positively correlated with the diversity of phosphate-solubilizing bacteria. Our results provided a basis for revealing the mechanism for driving the effect of U. prolifera outbreak on rhizosphere functional microbial diversity of dominant halophytes in coastal wetlands.

Key words: Suaeda salsa, Ulva prolifera, rhizosphere phosphate-solubilizing bacteria, high-throughput sequencing.