Engineering the Rhizomicrobiome for Drought-Resilient Soil and Sustainable Agriculture

Depleting freshwater reservoirs and worsening droughts are major threats to global agricultural productivity. Water unavailability contributes to significant yield losses by inducing physiological changes in plants and damaging root and shoot architecture. Current farming practices are unsustainable and cannot address the challenges posed by droughts. Hence, consistent and sustainable approaches are required to develop climate-resilient, high-yielding crops with improved drought tolerance. The rhizomicrobiome comprises plant-associated bacterial communities that regulate plant productivity through nutrient uptake, induction of systemic immune resistance, conferment of stress tolerance against abiotic and biotic stressors, and secretion of growth-stimulating compounds. Rhizobacteria can impart drought tolerance through the production of phytohormones, exopolysaccharides (EPS), aminocyclopropane-1-carboxylate (ACC) deaminase, volatile organic compounds (VOCs), accumulation of osmolytes, and the regulation of plant stress-responsive genes. Engineering plant-associated bacterial communities is a viable, less resource-intensive, and eco-friendly approach for mitigating the damaging effects of drought in plants. Although several plant growth-promoting bacteria have been shown to combat drought stress, the effects of these individual strains are limited, and many have not been promising in field trials. Therefore, a holistic approach is required to engineer rhizobacterial communities that can systematically compete with drought. Contemporary strategies for rhizomicrobiome modulation include “omics” techniques, enrichment of desirable microbial populations in the rhizosphere, engineering of microbial pathways to overproduce drought-fighting compounds, and improvisation of bacterial signaling systems. Consistent efforts to engineer rhizosphere bacterial communities for drought mitigation and the development of unique bioinocula can catalyze the achievement of global food security in the face of a changing climate.