Precipitation changes reshape desert soil microbial community assembly and potential functions.

Understanding the responses of desert microbial communities to escalating precipitation changes is a significant knowledge gap in predicting future soil health and ecological function. Through a five-year precipitation manipulation experiment, we investigated the contrasting eco-evolutionary processes of desert bacteria and fungi that manifested in changes to the assembly and potential functions of the soil microbiome. Elevated precipitation increased the alpha diversity and network complexity of bacteria and fungi, proportion of non-dominant phyla, and abundance of carbon- and nitrogen-fixing bacteria and saprophytic, symbiotic, and pathogenic fungi. Conversely, decreased precipitation reduced the alpha diversity and network complexity of bacteria and fungi while increasing the proportion of non-dominant phyla, stability of the network, and abundance of functional genes related to carbon and nitrogen degradation, nitrification, and ammonification. This suggests that soil microbes may attenuate the negative effects of reduced precipitation by streamlining communities, enhancing carbon and nitrogen acquisition, and promoting nitrogen cycling. Furthermore, we revealed that soil properties and vegetation attributes explained approximately 27.86%-37.75% and 17.76%-22.84% of the variation in bacterial and fungal communities, respectively. Finally, we demonstrated that precipitation-driven soil nutrient content and vegetation attributes are the potentially critical factors in shaping the soil microbial assembly and functions. These findings provide a foundation for understanding the response of desert soil microbes to escalating climate change.