Metagenomic insights into the response of rhizosphere microbial to precipitation changes in the alpine grasslands of northern Tibet

Water changes caused by precipitation may affect the elemental cycle of ecosystems by influencing soil microorganisms. In this study, precipitation control experiment was conducted in semi-arid alpine grasslands in northern Tibet, and plots were set up and divided into increased water (IW) and decreased water (DW) plots. Moreover, the link between functional genes and soil environmental factors, and the responses of the microbial community functions to precipitation-induced water variations were studied using metagenomic sequencing. To clarify the roles of various proteins and metabolites in the semi-arid alpine grasslands of northern Tibet, functional annotations of clusters of orthologous groups of proteins, Kyoto Encyclopedia of Genes and Genomes, and carbohydrate-active enzyme of the sequencing data were conducted. The results showed that the absolute abundance of microbial functional genes in IW was significantly higher than that in the control check (CK, natural precipitation) and DW. However, the absolute abundance did not significantly differ between CK and DW. There was no significant difference among the four plant species (Stipa purpurea, Carex moocroftii, Othropis microphylla, and Artemisia capillaris) considered in this study. These results indicated that microbial functions were mainly affected by water and do not depend on the species, and that the effect of IW was greater than that of DW. Further, we found that soil C, N, K, and other nutrients play vital roles in microbial growth, microbial functional genes were not affected by pH; however, soil C, N, and K nutrients and functional genes were negative correlated. Overall, this study enhances our understanding of the responses of microorganisms to precipitation and can be used as a valuable reference for understanding the drought resistance of soil microorganisms in semi-arid and alpine regions.