Soil holobiont interplay and its role in protecting plants against salinity stress

Abstract

Salinity poses a significant challenge to global agricultural productivity, impacting plant growth, yield, soil fertility, and the composition of soil microbial communities. Moreover, salinity has a significant impact in shifting soil microbial communities and their functional profiles. Therefore, we explored and analyzed the intricate relationships among plant-associated microbes/microbiome, including plant growth-promoting bacteria, arbuscular mycorrhizal fungi (AMF), archaea, and viruses in alleviating salinity stress in plants. In this review, we have highlighted that salinity stress selectively enhances the growth of certain microbes such as Gammaproteobacteria, Bacteroidetes, Firmicutes, Acidobacteria, Euryarchaeota, Thaumarchaeota, Crenarchaeota, and lysogenic viruses, while decreasing the abundances of others (Alphaproteobacteria and Betaproteobacteria) and AMF root colonization. These microbes regulate water and nutrient uptake, decrease ionic and osmotic toxicity, enhance the syntheses of antioxidant enzymes (catalase and glutathione S-transferases) and osmolytes (erythrose and galactinol), increase phytohormone (indole-3 acetic acid) production, and activate salinity stress tolerance genes (SOD, APX, and SKOR) in plants. Furthermore, we meticulously examined the significance of soil microbiome and the need for multidisciplinary omics studies on the changes in soil microbiome composition and the relationships of synergistic holobiont in mitigating salinity stress in plants. Such studies will provide insights into the use of microbial components as a sustainable and eco-friendly approach to modulate salinity stress and enhance agricultural productivity.