Plant Growth Promoting Rhizobacteria in Amelioration of Salinity Stress: A Systems Biology Perspective

Abstract

Salinity affects plant growth and is a major abiotic stress that limits crop productivity. It is well-understood that environmental adaptations and genetic traits regulate salinity tolerance in plants, but imparting the knowledge gained towards crop improvement remain arduous. Harnessing the potential of beneficial microorganisms present in the rhizosphere is an alternative strategy for improving plant stress tolerance. This review intends to elucidate the understanding of salinity tolerance mechanisms attributed by plant growth promoting rhizobacteria (PGPR). Recent advances in molecular studies have yielded insights into the signaling networks of plant–microbe interactions that contribute to salt tolerance. The beneficial effects of PGPR involve boosting key physiological processes, including water and nutrient uptake, photosynthesis, and source-sink relationships that promote growth and development. The regulation of osmotic balance and ion homeostasis by PGPR are conducted through modulation of phytohormone status, gene expression, protein function, and metabolite synthesis in plants. As a result, improved antioxidant activity, osmolyte accumulation, proton transport machinery, salt compartmentalization, and nutrient status reduce osmotic stress and ion toxicity. Furthermore, in addition to indole-3-acetic acid and 1-aminocyclopropane-1-carboxylic acid deaminase biosynthesis, other extracellular secretions of the rhizobacteria function as signaling molecules and elicit stress responsive pathways. Application of PGPR inoculants is a promising measure to combat salinity in agricultural fields, thereby increasing global food production.

Inoculation of tomato plants with selected PGPR represents a feasible alternative to chemical fertilization under salt stress

“…). Our results confirmed that PGPR can minimize the negative effects of abiotic stresses, as previously indicated ( Qin et al, ; Ilangumaran and Smith , ). The rhizobacteria used in this study were resistant to salt stress (Tab.…”

“…Salt stress induces the accumulation of Na + ions and nutritional imbalance in plant tissues, water content loss, and finally growth suppression and yield reduction ( Cuartero and Fernández‐Muñoz , ). Multiple studies have reported that the use of selected PGPR strains may alleviate salt stress in crops ( Qin et al, ; Ilangumaran and Smith , ).…”

Pseudomonas knackmussiiMLR6, a rhizospheric strain isolated from halophyte, enhances salt tolerance inArabidopsis thaliana

“…). PGPR can induce salinity stress tolerance through the modulation of physiological and biochemical process (Ilangumaran and Smith ). They can also induce systemic resistance (Yang et al .…”

“…auxin, cytokinin, ethylene and gibberellins), nitrogen fixation, nutrient mobilization and siderophore production (Hayat et al 2010). PGPR can induce salinity stress tolerance through the modulation of physiological and biochemical process (Ilangumaran and Smith 2017). They can also induce systemic resistance (Yang et al 2009).…”

The combination of arbuscular mycorrhizal fungi inoculation (Glomus versiforme) and 28‐homobrassinolide spraying intervals improves growth by enhancing photosynthesis, nutrient absorption, and antioxidant system in cucumber (Cucumis sativus L.) under salinity

“…Plants in their natural environment are colonized by a wide array of microbes, including nitrogen-fixing bacteria, endophytes (Ilangumaran & Smith, 2017). Arbuscular mycorrhizal fungi are ubiquitous among the vast array of microbes inhabiting the rhizosphere of the plants (Egamberdieva, Wirth, Li, Abd-Allah, & Lindström, 2017).…”