Bioaugmentation Improves Phytoprotection in Halimione Portulacoides Exposed to Mild Salt Stress: Perspectives for Salinized Soil Restoration

Rhizosphere bacteria have a decisive influence on plant ionic adjustment, as well as in ameliorating plant growth under an array of stress situations. Plant growth-promoting rhizobacteria (PGPR) colonize the rhizosphere of plants and promote plant growth through mechanisms such as solubilization of mineral phosphates, biological N2 fixation, production of siderophores and phytohormones, and can induce systemic resistance in the plant. This can be of extreme importance when considering the restoration of salinized grounds by halophytic species. This present work aims to evaluate the physiological fitness and phytoprotection improvement by salt marsh PGPR in Halimione portulacoides under mild and severe salt stress. Plants inoculated with PGPR-consortium showed higher photochemical performances, improved antioxidant response, and promotion of osmotic balance traits, that boosted the individual’s ability to cope with mild salt stress. All these changes are also in line with the differential elemental profiles (Na, K, and Ca) observed in the different plant tissues. Even under severe salt stress, some physiological traits were improved when compared to the non-inoculated individuals. The results developed under this work, point out an important role of bioaugmentation in promoting plant fitness and improving salt tolerance, with a great potential for applications in seawater agriculture, restoration, and bio-reclamation of salinized soils.