Bacterial taxa regulate the soil functionality of halophyte rhizospheres in saline‒alkali grassland ecosystems

Soil health and function in saline‒alkali grassland ecosystems are threatened. Understanding the factors that influence the ability of soil to perform multiple functions (soil multifunctionality) is crucial for developing effective remediation strategies. However, which plant species can improve soil functionality, and their impact mechanisms remain unclear. Metagenomics sequencing was employed to investigate the microbial community of four halophyte rhizospheres and bulk soil, and soil multifunctionality were evaluated using the averaging approach to identify potential species facilitating soil remediation and their underlying mechanisms. The alpha diversity of fungal and bacterial communities was significantly higher in halophyte rhizospheres compared to bulk soil, whereas archaeal diversity decreased. Rhizosphere microbial networks had higher topological attributes and complexity, and Proteobacteria , Actinobacteriota , and Euryarchaeota were identified as core taxa in interaction networks. Microbial diversity and abundance were related to soil salinity and conductivity. Halophyte growth, particularly that of Salicornia europaea and Kalidium foliatum , improved soil ecological functions (e.g., N-available nutrients, C/N enzyme activities, C/N cycling functional indices, and multifunctionality). Bacterial taxa exhibited stronger and more positive association with soil functionality than fungal or archaeal taxa, and bacterial community was influenced by fungal diversity and other taxa. Overall, halophytes regulated soil microbial communities by influencing the rhizosphere soil environment, thereby enhancing soil multifunctionality; this positive effect was mainly driven by bacterial diversity and specific taxa abundance. Enriching bacterial communities may help maintain soil multifunctionality in saline‒alkali ecosystems, and microorganism-driven phytoremediation strategies should focus on these biotic features to improve saline‒alkali ecosystems.