The rhizosphere under pressure: abiotic stress, microbiome dynamics, and plant resilience

Plant-associated microbiomes play important roles in plant adaptation to changing environments, while environmental conditions simultaneously shape microbiome assembly and function. Drought, salinity, and unfavorable pH conditions represent major constraints to plant growth and agricultural productivity and can substantially restructure microbial communities across plant-associated compartments. In turn, these microbiome changes can influence plant resilience through regulation of nutrient and water acquisition, ion homeostasis, phytohormone signaling, antioxidant defense, and stress-responsive pathways. Importantly, environmentally induced microbiome restructuring can also influence plant disease outcomes by altering pathogen suppression, host immunity, and interactions between beneficial and pathogenic microorganisms. This review synthesizes recent advances in understanding the reciprocal interactions between plant-associated microbiomes and drought, salinity, and soil pH, with particular emphasis on the mechanisms underlying microbiome assembly and microbial contributions to plant adaptation. We further examine how these environmental constraints reshape microbiome-mediated disease suppression and discuss emerging strategies for engineering stress-resilient microbial communities. Synthetic microbial communities and top-down microbiome engineering provide complementary approaches for translating mechanistic knowledge of plant-microbiome interactions into agricultural applications. However, the context dependency of microbial functions, community stability, host compatibility, and interactions with resident microbiota remain major challenges. A deeper mechanistic understanding of plant-microbiome-environment interactions will be essential for developing robust microbiome-based strategies to enhance crop resilience and plant health under increasingly variable environmental conditions.