Microbial transcriptome patterns highlight increased pedogenesis-related activity in arid soils under simulated humid...

In arid and semiarid environments, microbial activity is restricted by low water availability and high evapotranspiration rates, and soil development is limited. Under humid conditions, such limitations can be overcome, accelerating pedogenesis by microbial processes. Our study aims to broaden our understanding of soil development under a climate change scenario toward humid conditions and to identify the microorganisms that help transform initial soils from arid and semiarid sites. We characterized pedogenetic microbial processes and how their gene expression differs between soils from arid and semiarid sites under a sixteen-week climate simulation experiment using metagenomic and metatranscriptomic approaches.

We found that an intense functional response is triggered under humid climate conditions in the arid site compared to the semiarid site, which showed greater resilience. The arid site undergoes higher transcription of genes involved in soil aggregate formation, phosphorus metabolism, and weathering, potentially adapting the development of arid sites to climate change. Additionally, a transcriptional reconfiguration linked to soil carbon and nitrogen dynamics suggests that soil microorganisms use available organic resources alongside autotrophy in response to increased moisture. Pseudomonadota and Actinomycetota dominated the overall transcriptional profile and specific functions associated with the early stages of soil development in both sites.

Our findings highlight the rapid activation of pathways related to pedogenesis under humid conditions in arid sites, potentially driven by their metabolic requirements and environmental stressors, influencing soil development dynamics under global climate change.