scholarly journals Plant-Growth-Promoting Bacteria Mitigating Soil Salinity Stress in Plants

2020 ◽  
Vol 10 (20) ◽  
pp. 7326
Author(s):  
Stefan Shilev

Soil deterioration has led to problems with the nutrition of the world’s population. As one of the most serious stressors, soil salinization has a negative effect on the quantity and quality of agricultural production, drawing attention to the need for environmentally friendly technologies to overcome the adverse effects. The use of plant-growth-promoting bacteria (PGPB) can be a key factor in reducing salinity stress in plants as they are already introduced in practice. Plants having halotolerant PGPB in their root surroundings improve in diverse morphological, physiological, and biochemical aspects due to their multiple plant-growth-promoting traits. These beneficial effects are related to the excretion of bacterial phytohormones and modulation of their expression, improvement of the availability of soil nutrients, and the release of organic compounds that modify plant rhizosphere and function as signaling molecules, thus contributing to the plant’s salinity tolerance. This review aims to elucidate mechanisms by which PGPB are able to increase plant tolerance under soil salinity.

Agronomy ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 989 ◽  
Author(s):  
Noshin Ilyas ◽  
Roomina Mazhar ◽  
Humaira Yasmin ◽  
Wajiha Khan ◽  
Sumera Iqbal ◽  
...  

Halo-tolerant plant growth-promoting rhizobacteria (PGPR) have the inherent potential to cope up with salinity. Thus, they can be used as an effective strategy in enhancing the productivity of saline agro-systems. In this study, a total of 50 isolates were screened from the rhizospheric soil of plants growing in the salt range of Pakistan. Out of these, four isolates were selected based on their salinity tolerance and plant growth promotion characters. These isolates (SR1. SR2, SR3, and SR4) were identified as Bacillus sp. (KF719179), Azospirillum brasilense (KJ194586), Azospirillum lipoferum (KJ434039), and Pseudomonas stutzeri (KJ685889) by 16S rDNA gene sequence analysis. In vitro, these strains, in alone and in a consortium, showed better production of compatible solute and phytohormones, including indole acetic acid (IAA), gibberellic acid (GA), cytokinin (CK), and abscisic acid (ABA), in culture conditions under salt stress. When tested for inoculation, the consortium of all four strains showed the best results in terms of improved plant biomass and relative water content. Consortium-inoculated wheat plants showed tolerance by reduced electrolyte leakage and increased production of chlorophyll a, b, and total chlorophyll, and osmolytes, including soluble sugar, proline, amino acids, and antioxidant enzymes (superoxide dismutase, catalase, peroxidase), upon exposure to salinity stress (150 mM NaCl). In conclusion, plant growth-promoting bacteria, isolated from salt-affected regions, have strong potential to mitigate the deleterious effects of salt stress in wheat crop, when inoculated. Therefore, this consortium can be used as potent inoculants for wheat crop under prevailing stress conditions.


Author(s):  
Jennifer Lolitha C. ◽  
Manjula A. C. ◽  
Prathibha K. Y. ◽  
Keshamma E.

Rhizosphere, phylloplane and caulosphere is the region where a complex community of microbes, mainly bacteria and fungi are present. The microbe- plant interaction in these regions can be beneficial, neutral, variable, or deleterious for plant growth. The bacteria that exert beneficial effects on plant development are termed plant growth promoting bacteria. To isolate the bacteria from rhizosphere, phylloplane and caulosphere of brinjal (Solanum melongena L.). The seeds of 16 cultivars of brinjal (Solanum melongena L.) viz., Arka keshav, Arka shirish, Arka kusumaker, and IIHR accession numbers 389,386,387,377 Tc, BB44, 391, 433, 434, 427, 447, 448, 476 and 487 that were used in the initial screening experiment were obtained from the Department of Vegetable crops, IIHR, Hessaraghatta, Bangalore. Brinjal (Solanum melongena L.) plants of different varieties were collected from seven locations around Bangalore viz., Hessaraghatta, Yelahanka, Kengeri, Madi vala, Hebbal, Tirumalapura and Attibele were also screened for the presence of associative bacteria. Associative microorganisms isolated from the rhizosphere, phylloplane and shoot regions of brinjal (Solanum melongena L.), revealed the presence of three morphologically different colonies. 80% of 16 cultivars of the brinjal (Solanum melongena L.) screened showed the presence of associative bacterial colonies. In this study diazotrophic BBI were obtained from the rhizoplane, phylloplane and stem of 16 cultivars of brinjal (Solanum melongena L.) that were screened. The dominant pearl-colored colonies isolated from all varieties of brinjal plants that were screened was identified and showed maximum nitrogen fixing ability compared with that of the other colonies. The phylloplane of brinjal (Solanum melongena L.) plants from seven different locations around Bangalore showed the presence of the dominant pearl-colored colonies.  Moderate growth of bacteria was observed in root, stem and leaf bits sterilized up to 35 minutes. Even on surface sterilized roots which were homogenized and inoculated on growth media, dense growth of bacteria was observed there by establishing the presence of bacteria inside the root system. For the first time the presence of growth promoting bacteria on the rhizosphere and endorhizosphere of brinjal (Solanum Melongena L.) cultivars was established.


Agriculture ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 521
Author(s):  
Arash Hosseinpour ◽  
Kamil Haliloglu ◽  
Kagan Tolga Cinisli ◽  
Guller Ozkan ◽  
Halil Ibrahim Ozturk ◽  
...  

Salinity is an edaphic stress that dramatically restricts worldwide crop production. Nanomaterials and plant growth-promoting bacteria (PGPB) are currently used to alleviate the negative effects of various stresses on plant growth and development. This study investigates the protective effects of different levels of zinc oxide nanoparticles (ZnO-NPs) (0, 20, and 40 mg L−1) and PGPBs (no bacteria, Bacillus subtilis, Lactobacillus casei, Bacillus pumilus) on DNA damage and cytosine methylation changes in the tomato (Solanum lycopersicum L. ‘Linda’) seedlings under salinity stress (250 mM NaCl). Coupled Restriction Enzyme Digestion-Random Amplification (CRED-RA) and Randomly Amplified Polymorphic DNA (RAPD) approaches were used to analyze changes in cytosine methylation and to determine how genotoxic effects influence genomic stability. Salinity stress increased the polymorphism rate assessed by RAPD, while PGPB and ZnO-NPs reduced the adverse effects of salinity stress. Genomic template stability was increased by the PGPBs and ZnO-NPs application; this increase was significant when Lactobacillus casei and 40 mg L−1 of ZnO-NPs were used.A decreased level of DNA methylation was observed in all treatments. Taken together, the use of PGPB and ZnO-NPs had a general positive effect under salinity stress reducing genetic impairment in tomato seedlings.


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