Altitudinal variation in rhizosphere microbial communities of the endangered plant and the environmental factors driving this variation.

Unlabelled: The rhizosphere soil properties and microbial communities of , an endangered wild plant, have not been examined in previous studies. Here, we characterized spatial variation in soil properties and microbial communities in the rhizosphere of . We measured the abundance of at different altitudes and collected rhizosphere and bulk soils at three representative altitudes. The results showed that was more abundant, and the rhizosphere soil was richer in nitrogen, phosphorus, potassium, water content, and organic matter and more acidic at high altitudes than at lower altitudes. The diversity and richness of rhizosphere bacteria and fungi increased with altitude and were higher in rhizosphere soil than in bulk soil. In addition, ectomycorrhizal fungi, endophytic fungi, and nitrogen-fixing bacteria were more abundant, and plant-pathogenic fungi were less abundant at high altitudes. Co-occurrence network analysis identified four key phyla (Bacteroidota, Proteobacteria, Ascomycota, and Basidiomycota) in the microbial communities. We identified a series of microbial taxa (Acidobacteriales, Xanthobacteraceae, and Chaetomiaceae) and rhizosphere soil metabolites (phosphatidylcholine and phosphatidylserine) that are crucial for the survival of . Correlation analysis and random forest analysis showed that some environmental factors were closely related to the rhizosphere soil microbial community and played an important role in predicting the distribution and growth status of . In sum, the results of this study revealed altitudinal variation in the rhizosphere microbial communities of and the factors driving this variation. Our findings also have implications for habitat restoration and the conservation of this species.

Importance: Our study highlighted the importance of the rhizosphere microbial community of the endangered plant . We found that soil pH plays an important role in the survival of . Our results demonstrated that a series of microbial taxa (Acidobacteriales, Xanthobacteraceae, Aspergillaceae, and Chaetomiaceae) and soil metabolites (phosphatidylcholine and phosphatidylserine) could be essential indicators for habitat. We also found that some environmental factors play an important role in shaping rhizosphere microbial community structure. Collectively, these results provided new insights into the altitudinal distribution of and highlight the importance of microbial communities in their growth.