Vol. 11, Issue 6 (2022)

Author(s):
Nadiya Hasan and Suchit A John

Abstract:
Salinity is one of the most dreadful environmental factors limiting the productivity of crop plants because most of the crop plants are susceptible to salinity caused by high concentrations of salts in the soil, and the area of land affected by it is increasing day by day. Plant growth-promoting rhizobacteria (PGPR) are the rhizosphere bacteria that can increase plant growth by a extensive variety of mechanisms like phosphate solubilization, siderophore production, biological nitrogen fixation, rhizosphere engineering, production of 1 Aminocyclopropane-1- carboxylate deaminase (ACC), quorum sensing (QS) signal interference and inhibition of biofilm formation, phytohormone production, exhibiting antifungal activity, creation of volatile organic compounds (VOCs), induction of systemic resistance, promote beneficial plant-microbe symbioses etc. Growth promoting substances are probable to be produced in large quantities by these rhizosphere microorganisms that influence indirectly on the generally morphology of the plants. Bacterial inoculates have been applied as biofertilizers and can amplify the effectiveness of phytoremediation. Inoculating plants with non-pathogenic bacteria can provide ‘bioprotection’ against biotic stresses, and some root-colonizing bacteria increase tolerance against abiotic stresses such as salinity. Systematic identification of bacterial strains given that cross-protection against multiple stressors would be highly valuable for agricultural production in changing environmental conditions however, recent work shows that PGPR also elicit so-called ‘induced systemic tolerance to salt. As we discuss here, PGPR might also increase nutrient uptake from soils, thus reducing the need for fertilizers and prevent the accumulation of nitrates and phosphates in agricultural soils. The progress to date in using the rhizosphere bacteria in a variety of applications related to agricultural improvement along with their mechanism of action with special reference to plant growth-promoting traits are summarized and discussed in this review.