Halotolerant PGPR: A hope for cultivation of saline soils

Salt stress is one of the rapidly growing environmental stresses all over the world. Globally, 22% of the total cultivated and 33% of the total irrigated agricultural area is subjected to salt stress, which is increasing rapidly by an average of 10% per year. Due to this reason, 50% of cultivatable area will be salt-affected in coming years. On the other hand, demand for food is increasing with the rise in population. Salts have detrimental effects on plants such as damage to photosynthetic machinery, growth retardation and ultimately yield loss. However, the rhizosphere of plants harbors a diverse community of microbes known as halo-tolerant plant growth-promoting rhizobacteria (PGPR), which have the potential to cope with salinity problem. These PGPR assist plants to withstand the increased concentration of salts by the production of different organic and inorganic compounds such as Indole Acetic Acid (IAA), ethylene, 1-Amino Cyclopropane-1-Carboxylate (ACC) deaminase, volatile organic compounds (VOC), antioxidants etc.. The present review demonstrates the mechanisms of halo-tolerant PGPR that help plants to survive under saline conditions. We also highlighted some of the bacterial strains, which are successfully used in different forms on agriculturally important crops in salt affected soils. These halo-tolerant PGPR have the potential to work as defensive agents of plants by enhancing growth, productivity, tolerance and defense system under saline environments. (C) 2019 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University.