Understanding the potential of root microbiome influencing salt-tolerance in plants and mechanisms involved at the transcriptional and translational level.

Abstract

Soil salinity severely affects plant growth and development and imparts inevitable losses to crop productivity. Increasing the concentration of salts in the vicinity of plant roots has severe consequences at the morphological, biochemical, and molecular levels. These include loss of chlorophyll, decrease in photosynthetic rate, reduction in cell division, ROS generation, inactivation of antioxidative enzymes, alterations in phytohormone biosynthesis and signalling, etc. The association of microorganisms, viz. plant growth-promoting rhizobacteria, endophytes, and mycorrhiza, with plant roots constituting the root microbiome can confer a greater degree of salinity tolerance in addition to their inherent ability to promote growth and induce defence mechanisms. The mechanisms involved in induced stress tolerance bestowed by these microorganisms involve the modulation of phytohormone biosynthesis and signalling pathways (including indole acetic acid, gibberellic acid, brassinosteroids, abscisic acid, and jasmonic acid), accumulation of osmoprotectants (proline, glycine betaine, and sugar alcohols), and regulation of ion transporters (SOS1, NHX, HKT1). Apart from this, salt-tolerant microorganisms are known to induce the expression of salt-responsive genes via the action of several transcription factors, as well as by post-transcriptional and post-translational modifications. Moreover, the potential of these salt-tolerant microflorae can be employed for sustainably improving crop performance in saline environments. Therefore, the This review will briefly focus on the key responses of plants under salinity stress and elucidate the mechanisms employed by the salt-tolerant microorganisms in improving plant tolerance under saline environments. This article is protected by copyright. All rights reserved.