Halotolerant Plant Growth-Promoting Rhizobacteria Isolated From Saline Soil Improve Nitrogen Fixation and Alleviate Salt Stress in Rice Plants

Abstract

Salinity is one of the most damaging abiotic stresses due to climate change impacts that affect the growth and yield of crops, especially in lowland rice fields and coastal areas. This research aimed to isolate potential halotolerant plant growth-promoting rhizobacteria from different rhizo-microbiome and use them as effective bioinoculants to improve rice growth under salinity stress conditions. Bioassay using rice seedlings was performed in a randomized block design consisting of 16 treatments (control and 15 bacterial isolates) with three replications. Results revealed that isolates S3, S5, and S6 gave higher shoot height, root length, and plant dry weight compared with control (without isolates). Based on molecular characteristics, isolates S3 and S5 were identified as Pseudomonas stutzeri and Klebsiella pneumonia. These isolates were able to promote rice growth under salinity stress conditions as halotolerant plant growth-promoting rhizobacteria. These three potent isolates were found to produce indole-3-acetic acid and nitrogenase.

Insight into Recent Progress and Perspectives in Improvement of Antioxidant Machinery upon PGPR Augmentation in Plants under Drought Stress: A Review

“…The inoculation of native PGPR strains enhances the growth of autochthonous shrubs strongly associated with nutrient acquisition from the soil without altering microbial diversity in the rhizosphere [ 107 , 108 , 109 ]. Moreover, the PGPR properly supplements the mineral nutrients to crop plants that can help to minimize drought stress by actively participating in defensive processes, such as antioxidant systems and osmoregulation [ 33 , 90 , 110 ]. Therefore, the evidence suggests that PGPR-mediated uptake and enrichment of essential nutrients in plants play a pivotal role in enhancing their growth and drought resistance.…”

Evaluation of Plant Growth Promoting of Salt-tolerant Rhizobacteria Isolated from Egyptian Saline Soils

“…Among isolates, twelve have high ability to grow under high NaCl concentrations. Another study by Khumairah et al (2022) isolated three potential halotolerant plant growthpromoting rhizobacteria from different rhizo-microbiome of rice plant. These three potent isolates were found to produce indole-3-acetic acid and nitrogenase and were identified as Pseudomonas stutzeri and Klebsiella pneumonia based on molecular characteristics.…”

“…The application of plant growth promoting rhizobacteria as natural eco-friendly tools was found to be effective in mitigating the detrimental effects of salt stress conditions on plants (Kapadia et al, 2022). Several mechanisms for plant growth promoting rhizobacteria to mitigate salinity have been reported, including improved plant water relations, ion homeostasis, and photosynthetic efficiency in plants (Khumairah et al, 2022). The increased input of Na + and Cl − ions can induce nutrient imbalances, however beneficial microbes can reduce these imbalances by increasing the mineral nutrient exchange of both macro and micronutrients by improving mineralization, rhizosphere pH alterations through organic acids production, and metal chelation through siderophore production (Ilangumaran and Smith, 2017).…”

Exploring the Plant Growth-Promotion of Four Streptomyces Strains from Rhizosphere Soil to Enhance Cucumber Growth and Yield

“…PGPB colonizes the rhizosphere and facilitates plant growth directly by stimulating the growth or indirectly via biocontrol of the phytopathogens. The direct plant growth stimulation activity is through increased availability of nutrients, such as synthesis of phytohormones (i.e., auxin, cytokinins, gibberellins, abscisic acid) [ 3 ], bio-fixation of atmospheric nitrogen [ 4 ], production of siderophores (iron sequestration) [ 5 ], solubilization of soil minerals (i.e., phosphorus and potassium) [ 6 , 7 ], ACC (1-Aminocyclopropane-1-Carboxylate) deaminase activity [ 8 ], and in various other ways [ 9 , 10 , 11 , 12 ]. The indirect mechanisms involve biocontrol of phytopathogens through antibacterial and antifungal biomolecules [ 13 ], development of resistance against phytopathogens (i.e., soil-borne disease) [ 14 , 15 , 16 , 17 ], and competition for nutrients [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ].…”