Precipitation-Driven Restructuring of Rhizosphere Microbiota Enhances Alpine Plant Adaptation

Chen Chao¹Dafeng Xu¹Benli Jiang¹Xianyong Lu¹Chun Yu¹Yujiao Wang¹Hongjuan Wang¹Jingna Li²Jiabao Zhu^1*

• ¹Anhui Academy of Agricultural Sciences (CAAS), Hefei, China
• ²Hefei Normal University, Hefei, China

Climate-driven precipitation changes threaten alpine ecosystems, yet the adaptation mechanisms of soil microbiomes to rainfall variability remain poorly understood. This study employed metagenomic sequencing and physicochemical analyses to investigate how precipitation events reshape the microbial communities in rhizosphere and bulk soils associated with Poa alpigena in the alpine sandy ecosystems of Qinghai Lake. Our results demonstrated that rainfall significantly reduced bacterial alpha diversity, especially in bulk soils, and drove a compositional transition from drought-resistant taxa (e.g., Geobacter, Pseudomonas) to moisture-adapted genera (e.g., Azospirillum, Methylobacterium). Notably, Actinobacteria remained consistently dominant (31.56-34.62%), while Proteobacteria abundance declined sharply in the rhizosphere after rain. Metabolic profiling revealed a shift from pre-rainfall carbohydrate catabolism to post-rainfall anaerobic energy production and carbon fixation pathways. Rhizosphere microbiomes uniquely exhibited drought-induced biofilm formation and rainfall-enhanced branched-chain amino acid metabolism. Soil moisture and total carbon were identified as key drivers of microbial restructuring in bulk soils, whereas root exudates buffered rhizosphere communities against hydrological fluctuations. These findings elucidate microbiome-mediated adaptive strategies to precipitation changes in alpine sandy ecosystems and provide a scientific basis for the restoration of climate-vulnerable wetlands under increasingly variable hydrological regimes.