Mechanisms of plant response to salt and drought stress and their alteration by rhizobacteria.

Background: Soil salinity and drought are an enormous worldwide problem for agriculture, horticulture and silviculture. The initial responses of plants to drought and salinity are similar; both are attributed to water deficit which inhibits plant growth and development. Scope: In this review, an overview of the major physiological and biochemical changes that occur in plants as a consequence of salt and drought stress is presented. In addition, the role of beneficial plant growth-promoting bacteria in ameliorating many of the deleterious consequences of salt and drought stress is discussed. Mechanisms used by plant growth-promoting bacteria to ameliorate the effects of these stresses include the production of cytokinin, indoleacetic acid, ACC deaminase, abscisic acid, trehalose, volatile organic compounds, and exopolysaccharides. Conclusion: Given the fundamental understanding of many of the mechanisms operating in plant-bacterial interactions, it is expected that the practical use of beneficial bacteria in agriculture, horticulture and silviculture will grow dramatically in the coming years. [ABSTRACT FROM AUTHOR]