Medicinal plant‐associated rhizobacteria enhance the production of pharmaceutically important bioactive compounds under abiotic stress conditions

Interest in cultivating valuable medicinal plants to collect bioactive components has risen extensively over the world to meet the demands of health care systems, pharmaceuticals, and food businesses. Farmers commonly use chemical fertilizers to attain maximal biomass and yield, which have negative effects on the growth, development, and bioactive constituents of such medicinally important plants. Because of its low cost, environmentally friendly behavior, and nondestructive impact on soil fertility, plant health, and human health, the use of beneficial rhizobial microbiota is an alternative strategy for increasing the production of useful medicinal plants under both standard and stressed conditions. Plant growth-promoting rhizobacteria (PGPR) associated with medicinal plants belong to the genera Azotobacter, Acinetobacter, Bacillus, Brevibacterium, Burkholderia, Exiguobacterium, Pseudomonas, Pantoea, Mycobacterium, Methylobacterium, and Serratia. These microbes enhance plant growth parameters by producing secondary metabolites, including enzymes and antibiotics, which help in nutrient uptake, enhance soil fertility, improve plant growth, and protect against plant pathogens. The role of PGPR in the production of biomass and their effect on the quality of bioactive compounds (phytochemicals) is described in this review. Additionally, the mitigation of environmental stresses including drought stress, saline stress, alkaline stress, and flooding stress to herbal plants is illustrated.