Plant Growth-Promoting Rhizobacteria (PGPR) as Biofertilizers and Biopesticides

Plant growth-promoting rhizobacteria (PGPR) play an important role in sustainable agriculture through the improvement of plant growth via different processes like biological nitrogen fixation, phosphate solubilization, siderophore production, and phytohormone synthesis. The use of PGPR is potentially increased in sustainable farming due to its ecofriendly and efficient nature. It is being used as an alternative source to minimize the increasing use of synthetic fertilizers and pesticides. Biofertilizers are the substances containing living microbes, helping to improve plant growth and development. These living microorganisms enhance the nutrient status of soil through the expansion of root surface area, nitrogen fixation, phosphate solubilization, and combination of all these mechanisms. The market of the biofertilizers is expected to reach 3.8$ billion by 2025 from 2$ billion in 2019. Some Pseudomonas species also improve the plant growth through the production of water-soluble vitamins like niacin. PGPR have the potential to work as phytostimulators through the production of various phytohormones like indole acetic acid (IAA), cytokinin, gibberellins, and ethylene. But some bacteria and fungi have ability to improve plant growth by restricting the growth of plant pathogens are known as biopesticides. Cyanide biosynthesis, siderophore production, and induction of systemic resistance genes in plants are the different mechanisms for the PGPR to work against the plant pathogens. PGPR can also work as biocontrol agents providing protection to the plants, enhancing the plant growth through the synthesis of antibiotics. The use of the biopesticides is increasing slowly at a rate of 8% annually based on the different types of microbial pesticides.