scholarly journals Investigation of salt-tolerant rhizosphere bacteria from seawater-intruding paddy rice field in Vietnam

2020 ◽  
Vol 42 (3) ◽  
Author(s):  
Ho Tu Cuong ◽  
Bui Van Cuong ◽  
Lam Thuong Thuong ◽  
Tran Mai Hoang ◽  
Luong Thi Thu Huong ◽  
...  

Salt‐tolerant plant growth‐promoting rhizobacteria (ST‐PGPR) are known as potential tools to improve rice salinity tolerance. In this study, we aimed to investigate the plant growth‐promoting rhizobacteria community richness of the paddy rice fields in Soc Trang and Ben Tre Provinces where were seriously affected by sea level rise. The salinity in the sampling sites ranged from 0.14‰ to 2.17‰ in November 2018, the rainy season. The microbial abundance of samples was evaluated by spreading the samples in tryptic soy agar (TSA) medium supplemented with various concentrations of NaCl. With the increase of salt concentration up to 10% NaCl, a total number of bacteria decreased for all the samples, ranging from 106 to 104 CFU/g, and bacterial colonies were not observed at 30% NaCl. Among a total of 48 salt-resisting bacteria isolated from the rice paddy field mud surrounding the rice root, 22 isolates were able to produce indole-3-acetic acid (IAA: phytohormone for the plant growth). Seventeen out of 48 isolates were able to grow in the medium without nitrogen or phosphor sources. Six isolates having high IAA producing activity, nitrogen fixation and phosphate solubilization were belonged to Bacillus (DT6, LT16, and LHT8), Halobacillus (DT8), Aeromonas (LHT1), and Klebsiella (LHT7) genera. All the sequences of the strains DT6, DT8, LT16, LHT1, LHT7, and LHT8 were registered in the GeneBank with the accession numbers MK335670, MK335671, MK335672, MK335673, MK335674, and MK335675, respectively. 

2020 ◽  
Vol 66 (2) ◽  
pp. 144-160 ◽  
Author(s):  
Shahnaz Sultana ◽  
Sumonta C. Paul ◽  
Samia Parveen ◽  
Saiful Alam ◽  
Naziza Rahman ◽  
...  

Growth and productivity of rice are negatively affected by soil salinity. However, some salt-tolerant rhizosphere-inhabiting bacteria can improve salt resistance of plants, thereby augmenting plant growth and production. Here, we isolated a total of 53 plant-growth-promoting rhizobacteria (PGPR) from saline and non-saline areas in Bangladesh where electrical conductivity was measured as >7.45 and <1.80 dS/m, respectively. Bacteria isolated from saline areas were able to grow in a salt concentration of up to 2.60 mol/L, contrary to the isolates collected from non-saline areas that did not survive beyond 854 mmol/L. Among the salt-tolerant isolates, Bacillus aryabhattai, Achromobacter denitrificans, and Ochrobactrum intermedium, identified by comparing respective sequences of 16S rRNA using the NCBI GenBank, exhibited a higher amount of atmospheric nitrogen fixation, phosphate solubilization, and indoleacetic acid production at 200 mmol/L salt stress. Salt-tolerant isolates exhibited greater resistance to heavy metals and antibiotics, which could be due to the production of an exopolysaccharide layer outside the cell surface. Oryza sativa L. fertilized with B. aryabhattai MS3 and grown under 200 mmol/L salt stress was found to be favoured by enhanced expression of a set of at least four salt-responsive plant genes: BZ8, SOS1, GIG, and NHX1. Fertilization of rice with osmoprotectant-producing PGPR, therefore, could be a climate-change-preparedness strategy for coastal agriculture.


1996 ◽  
Vol 42 (3) ◽  
pp. 279-283 ◽  
Author(s):  
T. C. Noel ◽  
C. Sheng ◽  
C. K. Yost ◽  
R. P. Pharis ◽  
M. F. Hynes

Early seedling root growth of the nonlegumes canola (Brassica campestris cv. Tobin, Brassica napus cv. Westar) and lettuce (Lactuca saliva cv. Grand Rapids) was significantly promoted by inoculation of seeds with certain strains of Rhizobium leguminosarum, including nitrogen- and nonnitrogen-fixing derivatives under gnotobiotic conditions. The growfh-promotive effect appears to be direct, with possible involvement of the plant growth regulators indole-3-acetic acid and cytokinin. Auxotrophic Rhizobium mutants requiring tryptophan or adenosine (precursors for indole-3-acetic acid and cytokinin synthesis, respectively) did not promote growth to the extent of the parent strain. The findings of this study demonstrate a new facet of the Rhizobium–plant relationship and that Rhizobium leguminosarum can be considered a plant growth-promoting rhizobacterium (PGPR).Key words: Rhizobium, plant growth-promoting rhizobacteria, PGPR, indole-3-acetic acid, cytokinin, roots, auxotrophic mutants.


2019 ◽  
Vol 10 ◽  
Author(s):  
Dilfuza Egamberdieva ◽  
Stephan Wirth ◽  
Sonoko Dorothea Bellingrath-Kimura ◽  
Jitendra Mishra ◽  
Naveen K. Arora

Separations ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 223
Author(s):  
Clara de la Osa ◽  
Miguel Ángel Rodríguez-Carvajal ◽  
Jacinto Gandullo ◽  
Clara Aranda ◽  
Manuel Megías ◽  
...  

Background: The application of microorganisms as bioestimulants in order to increase the yield and/or quality of agricultural products is becoming a widely used practice in many countries. In this work, five plant growth-promoting rhizobacteria (PGPR), isolated from cultivated rice paddy soils, were selected for their plant growth-promoting capacities (e.g., auxin synthesis, chitinase activity, phosphate solubilisation and siderophores production). Two different tomato cultivars were inoculated, Tres Cantos and cherry. Plants were grown under greenhouse conditions and different phenotypic characteristics were analysed at the time of harvesting. Results: Tres Cantos plants inoculated with PGPR produced less biomass but larger fruits. However, the photosynthetic rate was barely affected. Several antioxidant activities were upregulated in these plants, and no oxidative damage in terms of lipid peroxidation was observed. Finally, ripe fruits accumulated less sugar but, interestingly, more lycopene. By contrast, inoculation of cherry plants with PGPR had no effect on biomass, although photosynthesis was slightly affected, and the productivity was similar to the control plants. In addition, antioxidant activities were downregulated and a higher lipid peroxidation was detected. However, neither sugar nor lycopene accumulation was altered. Conclusion: These results support the use of microorganisms isolated from agricultural soils as interesting tools to manipulate the level of important bioactive molecules in plants. However, this effect seems to be very specific, even at the variety level, and deeper analyses are necessary to assess their use for specific applications.


Rhizosphere ◽  
2019 ◽  
Vol 9 ◽  
pp. 10-17 ◽  
Author(s):  
Ahmad Mahmood ◽  
Rio Amaya ◽  
Oğuz Can Turgay ◽  
Ahmet Emre Yaprak ◽  
Takeshi Taniguchi ◽  
...  

Author(s):  
Arti Sharma ◽  
Kamal Dev ◽  
Anuradha Sourirajan ◽  
Madhu Choudhary

Abstract Background Soil salinity has been one of the biggest hurdles in achieving better crop yield and quality. Plant growth-promoting rhizobacteria (PGPR) are the symbiotic heterogeneous bacteria that play an important role in the recycling of plant nutrients through phytostimulation and phytoremediation. In this study, bacterial isolates were isolated from salt-polluted soil of Jhajjar and Panipat districts of Haryana, India. The potential salt-tolerant bacteria were screened for their PGPR activities such as phosphate solubilization, hydrogen cyanide (HCN), indole acetic acid (IAA) and ammonia production. The molecular characterization of potent isolates with salt tolerance and PGPR activity was done by 16S rDNA sequencing. Results Eighteen soil samples from saline soils of Haryana state were screened for salt-tolerant bacteria. The bacterial isolates were analyzed for salt tolerance ranging from 2 to 10%. Thirteen isolates were found salt tolerant at varied salt concentrations. Isolates HB6P2 and HB6J2 showed maximum tolerance to salts at 10% followed by HB4A1, HB4N3 and HB8P1. All the salt-tolerant bacterial isolates showed HCN production with maximum production by HB6J2. Phosphate solubilization was demonstrated by three isolates viz., HB4N3, HB6P2 and HB6J2. IAA production was maximum in HB4A1 (15.89) and HB6P2 (14.01) and least in HB4N3 (8.91). Ammonia production was maximum in HB6P2 (12.3) and least in HB8P1 (6.2). Three isolates HB6J2, HB8P1 and HB4N3 with significant salt tolerance, and PGPR ability were identified through sequencing of amplified 16SrRNA gene and were found to be Bacillus paramycoides, Bacillus amyloliquefaciens and Bacillus pumilus, respectively. Conclusions The salt-tolerant plant growth-promoting rhizobacteria (PGPR) isolated from saline soil can be used to overcome the detrimental effects of salt stress on plants, with beneficial effects of physiological functions of plants such as growth and yield, and overcome disease resistance. Therefore, application of microbial inoculants to alleviate stresses and enhance yield in plants could be a low cost and environmental friendly option for the management of saline soil for better crop productivity.


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