Plant–Soil Microbial Interaction: Differential Adaptations of Beneficial vs. Pathogenic Bacterial and Fungal Communities to Climate-Induced Drought

Climate change and the increasing frequency and severity of drought events pose significant challenges for sustainable agriculture worldwide. Soil microorganisms, both beneficial and pathogenic, play a crucial role in mediating plant–environment interactions and shaping the overall functioning of agroecosystems. This review summarizes current knowledge on the adaptive mechanisms used by different groups of plant-beneficial soil microorganisms—rhizobacteria and arbuscular mycorrhizal fungi (AMF)—as well as phytopathogenic bacteria and fungi, in response to drought. The review focuses on identifying the commonalities and differences in the survival strategies of these groups of beneficial and pathogenic soil microorganisms under drought conditions. Additionally, it reviews and compares the plant defence mechanisms under drought conditions facilitated by rhizobacteria and AMF. Special attention is given to the genetic exchange between beneficial and pathogenic soil microorganisms through horizontal gene transfer (HGT), which allows them to exchange traits. It is observed that drought may favor enhanced genetic exchange and the spread of pathogenic traits in the soil microbiome. This review will be useful for a wide range of readers to better understand the dynamics of the soil microbiome under climate change and to apply this knowledge to sustainable agricultural practices.