Rooting for microbes: Impact of root architecture on the microbial community and function in top- and subsoil

Background and Aims Climate change and associated weather extremes pose major challenges to agricultural food production, necessitating the development of more resilient agricultural systems. Adapting cropping systems to cope with extreme environmental conditions is a critical challenge. This study investigates the influence of contrasting root system architectures on microbial communities and functions in top- and subsoil. Methods A column experiment was performed to investigate the effects of different root architectures, specifically deep (DRS) and shallow (SRS) root systems of wheat ( Triticum aestivum L.) on microbial biomass, major microbial groups, and extracellular enzyme activities in soil. It focused on β-glucosidase (BG) during different plant growth stages, using destructive and non-destructive approaches. Results We found that the DRS promoted formation of microbial hotspots in subsoil leading to an increase in microbial biomass and enzyme activity, while the SRS favored formation of hotspots in topsoil. In-situ soil zymography provided fine-scale spatial insights, highlighting distinct patterns of BG activity near root centers and formation of enzymatic hotspots. Temporal changes in BG activity further underscored the dynamic nature of root-microbe interactions. Extracellular enzyme activities indicated varying carbon, nitrogen and phosphorus acquisition strategies of rhizosphere microorganisms between top- and subsoil. Conclusion This study underscores the need to consider root system architecture in agricultural strategies, as it plays a crucial role in influencing microbial communities and enzyme activities, ultimately affecting carbon and nutrient cycling processes in top- and subsoil.