Soil microbial diversity analysis of four typical halophytes in coastal saline-alkali land

Rhizosphere microorganisms are key functional mediators for regulating the soil microecology of saline-alkali lands. This study aimed to explore the microbial community structure, diversity characteristics, and functions in the rhizosphere and non-rhizosphere soils of halophytes grown in coastal saline land including Limonium bicolor (Bag.) Kuntze, Suaeda glauca (Bunge) Bunge, Suaeda salsa (L.) Pall., and Apocynum venetum L. by utilizing Illumina sequencing techniques. The results indicated that halophytes significantly increased soil microbial diversity. With the exception of Suaeda salsa (L.) Pall., the Chao1 and Shannon indices of bacteria in both the rhizosphere and non-rhizosphere soils of all plant groups were significantly higher than those of the control group. LEfSe analysis indicated that different halophytes enriched specific microbial taxa in their rhizosphere soils. A total of 27 bacterial taxa and 18 fungal taxa with significant differences were identified. Suaeda glauca significantly enriched Gemmatimonadota and Alphaproteobacteria, while Apocynum venetum significantly enriched Basidiomycota. The core metabolic functions of microorganisms were different that chemoheterotrophy and aerobic chemoheterotrophy were the core functions of rhizosphere bacteria (with their combined proportion accounting for >50%), and the rhizosphere of Apocynum venetum L. was significantly enriched in predatory or ectoparasitic functions; rhizosphere fungi were dominated by undefined saprotrophs and plant pathogens, among which the abundance of plant pathogens in the rhizosphere of Suaeda glauca reached as high as 45.5%, while arbuscular mycorrhizal fungi (AMF) were significantly enriched in the non-rhizosphere soil of Apocynum venetum L.. The study provides the basic information for screening functional microbial resources to improve soil quality of coastal saline lands.