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High salt tolerant plant growth promoting rhizobacteria from the common ice-plant Mesembryanthemum crystallinum L

Mahmood, Ahmad, Amaya, Rio, Turgay, Oğuz Can, Yaprak, Ahmet Emre, Taniguchi, Takeshi, Kataoka, Ryota
Rhizosphere 2019 v.9 pp. 10-17
1-aminocyclopropane-1-carboxylate deaminase, Mesembryanthemum crystallinum, energy requirements, enzyme activity, halophytes, host plants, indole acetic acid, land restoration, microbiome, nitrogen fixation, phosphorus, plant growth-promoting rhizobacteria, rhizosphere, rhizosphere bacteria, root growth, saline soils, salinity, salt tolerance, siderophores, sodium chloride, solubilization, vegetation
Prevalent salinity hinders the plant growth, and efforts for vegetation are limited due to excessive concentration of salts. The microbiome associated with extreme habitats has the potential of inducing stress avoidance, tolerance, and resistance strategies in the host plants for energy requirements. Manipulation of such interactions offers the potential revegetation, and utilization of saline soils, and with the similar objectives, the rhizosphere of Common ice-plant was explored for incident bacteria helping the plant grow better. The isolation resulted in 152 isolates, and above 50% isolates were observed tolerant to 513 mM of NaCl, and the two, PR-3 and PR-6, most promising even showed tolerance up to 1250 mM salinity. Both the strains showed indole acetic acid production, and 1-aminocyclopropane-1-carboxylate deaminase activity, but neither of them had nitrogen fixation ability. Phosphorus solubilization, and siderophore production was shown by either of them. Plant growth promoting (PGP) assay showed significant root elongation when compared with control, which was further confirmed by the pot experiment where the above-ground part of the Common ice-plant also showed significant growth over control. Concluding, rhizosphere bacteria from the halophyte plant showed different PGP abilities, and thus can be applied for improving the growth of associated plant in saline conditions.