Plant Growth Promoting Rhizobacteria to Mitigate Biotic and Abiotic Stress in Plants

Abstract

Plant growth promoting rhizobacteria are microbes that promote plant growth and alleviate plant stress such as salinity, flooding, heavy metals, drought, cold, soil compaction, mechanical impedance, and nutrient deficiency. This chapter reviews mechanisms that alleviate plant stress using microorganisms. Mechanisms include the production of phytohormones such as auxin, of volatiles such as hydro- gen cyanide and ammonia, of osmolytes such as proline and sugars, of exopolysac- charides, and the activation of antioxidant defence systems in plants. Under stress, the ethylene concentration increases in plants, leading to senescence and plant death. Here, plant growth promoting rhizobacteria favors the activity of 1- aminocy clopropane- 1-carboxylate deaminase, which indirectly reduce ethylene concentration.