METHYLOTROPHS AS PLANT RESCUERS: MECHANISTIC STRATEGIES FOR COMBATING ABIOTIC STRESS

Abstract

Climate change and environmental degradation have intensified the occurrence of abiotic stresses such as drought, salinity, extreme temperatures, heavy metal contamination, ultraviolet (UV) radiation, and nutrient deficiencies, posing major threats to global agricultural productivity and food security. Plants exposed to these stresses experience significant physiological, biochemical, and molecular disturbances, including impaired germination, reduced photosynthetic efficiency, oxidative damage, nutrient imbalance, growth inhibition, and yield losses. In recent years, plant-associated methylotrophic bacteria have emerged as promising microbial resources for enhancing plant resilience against diverse abiotic stresses. Methylotrophs, particularly members of the genera Methylobacterium and Methylorubrum, are ubiquitous colonizers of the phyllosphere, rhizosphere, and endosphere, where they utilize plant derived methanol and establish beneficial associations with host plants. This review comprehensively summarizes the biodiversity, ecological distribution, and functional characteristics of methylotrophic microbial communities, with special emphasis on their role in plant–microbe interactions and abiotic stress mitigation. The review discusses the detrimental effects of major abiotic stresses on plant growth, development, physiology, and productivity, and critically examines the underlying mechanisms through which methylotrophs confer stress tolerance. These mechanisms include phytohormone production, ACC deaminase activity, biological nitrogen fixation, phosphate solubilization, siderophore production, exopolysaccharide synthesis, osmotic adjustment, antioxidant enhancement, modulation of stress-responsive signaling pathways, and production of protective metabolites such as methylobamine. Overall, this review provides an integrated understanding of the ecological significance and biotechnological potential of methylotrophs in promoting climate-resilient and sustainable agricultural systems under increasingly challenging environmental conditions.