Analysis of fungal diversity and community structure in rhizosphere soil of three coastal halophytes at Laizhou bay, China

Halophytes harbor distinct microbial diversity and communities around their roots, which play a crucial ecological role on stress adaptation. However, there is limited knowledge about the fungi in rhizosphere soil of coastal halophytes at Laizhou bay in China. Thus, we aimed to explore the fungal diversity, composition, co-occurrence network and fungal functions in the rhizosphere soil of halophytes including Suaeda glauca (S. glauca, SG), Phragmites australis (P. australis, PA), Setaria viridis (S. viridis, SV) and bulk soil (CK), by utilizing Illumina sequencing techniques. A total of 1,867,704 reads and 2024 amplicon sequencing variants (ASVs) were found in all samples. We showed higher richness in fungal communities of halophyte rhizosphere soil (P. australis and S. viridis) than bulk soil, and SV group had more alpha diversity relative to SG group. The analysis of beta diversity showed clear separation across all groups except significant crossover between PA and SV groups. The more unique ASVs were found among all groups, PA and SV shared about three times number of ASVs than PA&SG or SV&SG group. Ascomycota was the most dominant phylum in all samples. In addition, the abundance of Ascomycota in the PA and SG groups, and Rozellomycota in the SV group, were higher than that in the CK group (p < 0.05). Interestingly, Monosporascus as fungal pathogen was the predominant fungal genus in the CK group, but decreased in rhizosphere soil of halophytes. Some genera including Talaromyces, Zopfiella, Exserohilum and Neocamarosporium had higher abundance in halophyte rhizosphere soil than that in bulk soil, and the genera with different abundance among groups depend on halophyte species. In addition, the halophyte rhizosphere soil had higher network size, modularity and similar fungal co-occurring network complexity comparing with bulk soil. Lastly, the fungal functionality showed decreased abundance of fungal pathogen, but higher saprotrophic functional guilds in halophyte rhizosphere than that in bulk soil. The study may contribute to understanding of the interactions between halophytic plants and their rhizosphere microbiota in saline-alkali soils, which may provide insights into potential microbial-based strategies for improving crop resilience and productivity in saline environments.