Figure 2.

Proposed model of PGPR and AM against abiotic stress in plants: Microorganisms colonize roots by using different mechanisms such as triggering an ionic and osmotic response. Microbial inoculation, such as PGPR indicated in brown on the plants’ roots, AM, and EM, indicated with a green solid arrow, are often reported to protect plants against water drought stress, thus increasing dehydration intolerance. PGPR, AM, and EM have shown to produce antioxidant activities (yellow arrow) such as catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), which improves osmotic adjustment in plants and secondary metabolites (broken blue arrows) such as cytokinin (CKs), gibberellins (GAs), ethylene (ET), and auxins (IAA), which elicit stress tolerance in plants, resulting in root surface area, root length, and the number of root tips. Antioxidants and secondary metabolites help in enhancing the uptake of nutrients from the soil by the roots to produce a high yield of plant crops [58].