Potential Role of Plant Growth Promoting Rhizobacteria in Alleviation of Biotic Stress

Plant growth promoting rhizobacteria (PGPR) are well known to ameliorate the plant health. A large number of rhizobacteria possess the growth promoting activities. Some of them are very common and has been also commercialised to large/industrial scale. Plant growth regulators have been found to induce the growth and development of various crop plants. Some hormones like auxin, cytokinin, IAA, etc. are the key hormones in the plant growth promotion. However, their ratio of auxin to cytokinin may be determinant in the lateral root or root hair formation. The root surface area and root lengths are also conceived to play very important role in the accumulation of nutrient and are significantly influenced by the application of PGPR. Moreover, PGPR also have the biocontrol activities against a wide range of soil-borne plant pathogens. Some organic molecules such as siderophores, antibiotics, and bacteriocins producing PGPR arrest the pathogen populations and improve the plant health indirectly. Presence of more PGPR in rhizosphere exhibits more vigour plant health. Therefore, PGPR is considered as an alternative and effective way in the management of plant pathogens and plant growth promotion.