scholarly journals Overview of the Role of Rhizobacteria in Plant Salt Stress Tolerance

Agronomy ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1759
Author(s):  
Miguel Ayuso-Calles ◽  
José David Flores-Félix ◽  
Raúl Rivas
Keyword(s):  
Salt Stress ◽  
Plant Growth ◽  
Osmotic Stress ◽  
Nutrient Deficiency ◽  
Cost Effective ◽  
Growth And Yield ◽  
Soil Conditions ◽  
Saline Stress ◽  
Plant Growth Promoting Bacteria ◽  
Plant Tolerance

Salinity is one of the main causes of abiotic stress in plants, resulting in negative effects on crop growth and yield, especially in arid and semi-arid regions. The effects of salinity on plant growth mainly generate osmotic stress, ion toxicity, nutrient deficiency, and oxidative stress. Traditional approaches for the development of salt-tolerant crops are expensive and time-consuming, as well as not always being easy to implement. Thus, the use of plant growth-promoting bacteria (PGPB) has been reported as a sustainable and cost-effective alternative to enhance plant tolerance to salt stress. In this sense, this review aims to understand the mechanisms by which PGPB help plants to alleviate saline stress, including: (i) changes in the plant hormonal balance; (ii) release of extracellular compounds acting as chemical signals for the plant or enhancing soil conditions for plant development; (iii) regulation of the internal ionic content of the plant; or iv) aiding in the synthesis of osmoprotectant compounds (which reduce osmotic stress). The potential provided by PGPB is therefore an invaluable resource for improving plant tolerance to salinity, thereby facilitating an increase in global food production and unravelling prospects for sustainable agricultural productivity.

scholarly journals USE OF PLANT GROWTH PROMOTING RHIZOBACTERIA AGAINST SALT STRESS FOR TOMATO (SOLANUM LYCOPERSICUM L.) SEEDLING GROWTH

2020 ◽  
Vol 19 (6) ◽  
pp. 15-29
Author(s):  
Yagmur Yilmaz ◽  
Ceknas Erdinc ◽  
Ahmet Akkopru ◽  
Selma Kipcak
Keyword(s):  
Salt Stress ◽  
Plant Growth ◽  
Pseudomonas Putida ◽  
Photosynthetic Pigment ◽  
Plant Growth Promoting Rhizobacteria ◽  
Growth And Yield ◽  
Plant Tolerance ◽  
Membrane Injury ◽  
Plant Growth Promoting ◽  
Growth Promoting

Salt stress affects many aspects of plant metabolism and as a result, growth and yield are reduced. The aim in this study was to determine the effects of plant growth promoting rhizobacteria (PGPR) on tomato plants under salt stress. With this aim, the Interland F1 cv. and bacterial isolates of Bacillus thuringiensis CA41/1, Pseudomonas putida 18/1K, Pseudomonas putida S5/4ep, and Pseudomonas putida 30 were used. Salt application was completed in two different doses of 25 and 50 mM NaCl when seedlings reached the stage of 3 true leaves. At the end of the study, in addition to seedling development criteria, some nutrient element contents and rates (K, Ca, Na, K/Na and Ca/Na), superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) enzyme activities, malondialdehyde (MDA) and photosynthetic pigment contents were determined. In the stress environment, PGPR inoculation increased K content by up to 10%, while apart from isolate P. putida no.30, the other isolates lowered Na content by up to 18%. Additionally, 18/1K and S5/4ep isolates were identified to reduce membrane injury index by up to 97%. It was identified that CA41/1, 18/1K and S5/4ep isolates were more effective against salt stress, especially. In general, the plant tolerance levels induced by the bacteria were identified to increase with the increase in salt stress.

scholarly journals PGPB Improve Photosynthetic Activity and Tolerance to Oxidative Stress in Brassica napus Grown on Salinized Soils

2021 ◽  
Vol 11 (23) ◽  
pp. 11442
Author(s):  
Massimiliano Rossi ◽  
Ilaria Borromeo ◽  
Concetta Capo ◽  
Bernard R. Glick ◽  
Maddalena Del Gallo ◽  
...  
Keyword(s):  
Salt Stress ◽  
Brassica Napus ◽  
Plant Growth ◽  
Bacterial Species ◽  
Membrane Damage ◽  
Photosynthetic Apparatus ◽  
Soil Salinization ◽  
Saline Stress ◽  
Plant Growth Promoting Bacteria ◽  
Oxidative Stresses

Soil salinization, one of the most common causes of soil degradation, negatively affects plant growth, reproduction, and yield in plants. Saline conditions elicit some physiological changes to cope with the imposed osmotic and oxidative stresses. Inoculation of plants with some bacterial species that stimulate their growth, i.e., plant growth-promoting bacteria (PGPB), may help plants to counteract saline stress, thus improving the plant’s fitness. This manuscript reports the effects of the inoculation of a salt-sensitive cultivar of Brassica napus (canola) with five different PGPB species (separately), i.e., Azospirillum brasilense, Arthrobacter globiformis, Burkholderia ambifaria, Herbaspirillum seropedicae, and Pseudomonas sp. on plant salt stress physiological responses. The seeds were sown in saline soil (8 dS/m) and inoculated with bacterial suspensions. Seedlings were grown to the phenological stage of rosetta, when morphological and physiological features were determined. In the presence of the above-mentioned PGPB, salt exposed canola plants grew better than non-inoculated controls. The water loss was reduced in inoculated plants under saline conditions, due to a low level of membrane damage and the enhanced synthesis of the osmolyte proline, the latter depending on the bacterial strain inoculated. The reduction in membrane damage was also due to the increased antioxidant activity (i.e., higher amount of phenolic compounds, enhanced superoxide dismutase, and ascorbate peroxidase activities) in salt-stressed and inoculated Brassica napus. Furthermore, the salt-stressed and inoculated plants did not show detrimental effects to their photosynthetic apparatus, i.e., higher efficiency of PSII and low energy dissipation by heat for photosynthesis were detected. The improvement of the response to salt stress provided by PGPB paves the way to further use of PGPB as inoculants of plants grown in saline soils.

scholarly journals Molecular Insight Into Key Eco-Physiological Process in Bioremediating and Plant-Growth-Promoting Bacteria

2021 ◽  
Vol 3 ◽  
Author(s):  
Subhrangshu Mandal ◽  
Kunal Kumar Saha ◽  
Narayan Chandra Mandal
Keyword(s):  
Heavy Metals ◽  
Plant Growth ◽  
Agricultural Sector ◽  
Cost Effective ◽  
Anthropogenic Activity ◽  
Plant Growth Promoting Bacteria ◽  
Genetic Landscape ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Legal Constraints

Over the past few decades, the massive increase in anthropogenic activity and industrialization processes has increased new pollutants in the environment. The effects of such toxic components (heavy metals, pesticides, etc.) in our ecosystem vary significantly and are of significant public health and economic concern. Because of this, environmental consciousness is increasing amongst consumers and industrialists, and legal constraints on emissions are becoming progressively stricter; for the ultimate aim is to achieve cost-effective emission control. Fortunately, certain taxonomically and phylogenetically diverse microorganisms (e.g., sulfur oxidizing/reducing bacteria) are endowed with the capability to remediate such undesired components from diverse habitats and have diverse plant-growth-promoting abilities (auxin and siderophore production, phosphate solubilization, etc.). However, the quirk of fate for pollutant and plant-growth-promoting microbiome research is that, even with an early start, genetic knowledge on these systems is still considered to be in its infancy due to the unavailability of in-depth functional genomics and population dynamics data from various ecosystems. This knowledge gap can be breached if we have adequate information concerning their genetic make-up, so that we can use them in a targeted manner or with considerable operational flexibility in the agricultural sector. Amended understanding regarding the genetic basis of potential microbes involved in such processes has led to the establishment of novel or advanced bioremediation technologies (such as the detoxification efficiency of heavy metals), which will further our understanding of the genomic/genetic landscape in these potential organisms. Our review aimed to unravel the hidden genomic basis and eco-physiological properties of such potent bacteria and their interaction with plants from various ecosystems.

scholarly journals Effect of Pyroligneous Acid on the Microbial Community Composition and Plant Growth-Promoting Bacteria (PGPB) in Soils

Soil Systems ◽  
2022 ◽  
Vol 6 (1) ◽  
pp. 10
Author(s):  
Anithadevi Kenday Sivaram ◽  
Logeshwaran Panneerselvan ◽  
Kannappar Mukunthan ◽  
Mallavarapu Megharaj
Keyword(s):  
Microbial Community ◽  
Plant Growth ◽  
Microbial Diversity ◽  
Growth And Yield ◽  
Rrna Gene ◽  
Plant Growth Promoting Bacteria ◽  
Microbial Composition ◽  
Pyroligneous Acid ◽  
Plant Growth Promoting ◽  
Growth Promoting

Pyroligneous acid (PA) is often used in agriculture as a plant growth and yield enhancer. However, the influence of PA application on soil microorganisms is not often studied. Therefore, in this study, we investigated the effect of PA (0.01–5% w/w in soil) on the microbial diversity in two different soils. At the end of eight weeks of incubation, soil microbial community dynamics were determined by Illumina-MiSeq sequencing of 16S rRNA gene amplicons. The microbial composition differed between the lower (0.01% and 0.1%) and the higher (1% and 5%) concentration in both PA spiked soils. The lower concentration of PA resulted in higher microbial diversity and dehydrogenase activity (DHA) compared to the un-spiked control and the soil spiked with high PA concentrations. Interestingly, PA-induced plant growth-promoting bacterial (PGPB) genera include Bradyrhizobium, Azospirillum, Pseudomonas, Mesorhizobium, Rhizobium, Herbaspiriluum, Acetobacter, Beijerinckia, and Nitrosomonas at lower concentrations. Additionally, the PICRUSt functional analysis revealed the predominance of metabolism as the functional module’s primary component in both soils spiked with 0.01% and 0.1% PA. Overall, the results elucidated that PA application in soil at lower concentrations promoted soil DHA and microbial enrichment, particularly the PGPB genera, and thus have great implications for improving soil health.

Salt-tolerant and plant-growth-promoting bacteria isolated from high-yield paddy soil

2018 ◽  
Vol 64 (12) ◽  
pp. 968-978 ◽  
Author(s):  
Shiying Zhang ◽  
Cong Fan ◽  
Yongxia Wang ◽  
Yunsheng Xia ◽  
Wei Xiao ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Plant Growth ◽  
Paddy Soil ◽  
Effective Strain ◽  
High Yield ◽  
Saline Stress ◽  
Plant Growth Promoting Bacteria ◽  
Salt Tolerant ◽  
Plant Growth Promoting ◽  
Growth Promoting

Growth and productivity of rice is negatively affected by soil salinity. However, some salt-tolerant bacteria improve the health of plants under saline stress. In this study, 305 bacteria were isolated from paddy soil in Taoyuan, China. Among these, 162 strains were tested for salt-tolerance; 67.3%, 28.4%, and 9.3% of the strains could grow in media with NaCl concentrations of 50, 100, and 150 g/L, respectively. The phylogenic analysis of 74 of these 162 strains indicates that these bacteria belong to Bacillales (72%), Actinomycetales (22%), Rhizobiales (1%), and Oceanospirillales (4%). Among 162 strains, 30 salt-tolerant strains were screened for their plant-growth-promoting activities under axenic conditions at 3, 6, 9, and 12 g/L NaCl; 43%–97% of the strains could improve rice germination energy or germination capacity, while 63%–87% of the strains could increase shoot and root lengths. Among various plant-growth-promoting bacteria, TY0307 was the most effective strain for promoting the growth of rice, even at high salt stress. Its promotor effects were associated with its production of 1-aminocyclopropane-1-carboxycarboxylate deaminase, indole acetic acid, and siderophores; induction of proline accumulation; and reduction of the salt-induced malondialdehyde content. These results suggest that several strains isolated from paddy soil could improve rice salt tolerance and may be used in the development of biofertilizer.

scholarly journals Burkholderia Phytofirmans PsJN Stimulate Growth and Yield of Quinoa under Salinity Stress

Plants ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 672 ◽  
Author(s):  
Aizheng Yang ◽  
Saqib Saleem Akhtar ◽  
Qiang Fu ◽  
Muhammad Naveed ◽  
Shahid Iqbal ◽  
...  
Keyword(s):  
Plant Growth ◽  
Salinity Stress ◽  
Endophytic Bacteria ◽  
Ion Homeostasis ◽  
Growth And Yield ◽  
Shoot Biomass ◽  
World Population ◽  
Plant Growth Promoting Bacteria ◽  
Ros Scavenging ◽  
Burkholderia Phytofirmans Psjn

One of the major challenges in agriculture is to ensure sufficient and healthy food availability for the increasing world population in near future. This requires maintaining sustainable cultivation of crop plants under varying environmental stresses. Among these stresses, salinity is the second most abundant threat worldwide after drought. One of the promising strategies to mitigate salinity stress is to cultivate halotolerant crops such as quinoa. Under high salinity, performance can be improved by plant growth promoting bacteria (PGPB). Among PGPB, endophytic bacteria are considered better in stimulating plant growth compared to rhizosphere bacteria because of their ability to colonize both in plant rhizosphere and plant interior. Therefore, in the current study, a pot experiment was conducted in a controlled greenhouse to investigate the effects of endophytic bacteria i.e., Burkholderia phytofirmans PsJN on improving growth, physiology and yield of quinoa under salinity stress. At six leaves stage, plants were irrigated with saline water having either 0 (control) or 400 mM NaCl. The results indicated that plants inoculated with PsJN mitigated the negative effects of salinity on quinoa resulting in increased shoot biomass, grain weight and grain yield by 12%, 18% and 41% respectively, over un-inoculated control. Moreover, inoculation with PsJN improved osmotic adjustment and ion homeostasis ability. In addition, leaves were also characterized for five key reactive oxygen species (ROS) scavenging enzyme in response to PsJN treatment. This showed higher activity of catalase (CAT) and dehydroascobate reductase (DHAR) in PsJN-treated plants. These findings suggest that inoculation of quinoa seeds with Burkholderia phytofirmans PsJN could be used for stimulating growth and yield of quinoa in highly salt-affected soils.

scholarly journals Alleviation of Salt Stress by Plant Growth-Promoting Bacteria in Hydroponic Leaf Lettuce

Agronomy ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1523 ◽  
Author(s):  
Alessandra Moncada ◽  
Filippo Vetrano ◽  
Alessandro Miceli
Keyword(s):  
Salt Stress ◽  
Plant Growth ◽  
Leafy Vegetables ◽  
Mineral Nutrient ◽  
Plant Growth Promoting Bacteria ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Leaf Lettuce ◽  
Positive Effect ◽  
Nutrient Solutions

Mediterranean areas with intensive agriculture are characterized by high salinity of groundwater. The use of this water in hydroponic cultivations can lead to nutrient solutions with an electrical conductivity that overcomes the tolerance threshold of many vegetable species. Plant growth-promoting rhizobacteria (PGPR) were shown to minimize salt stress on several vegetable crops but the studies on the application of PGPR on leafy vegetables grown in hydroponics are rather limited and have not been used under salt stress conditions. This study aimed to evaluate the use of plant growth-promoting bacteria to increase the salt tolerance of leaf lettuce grown in autumn and spring in a floating system, by adding a bacterial biostimulant (1.5 g L−1 of TNC BactorrS13 a commercial biostimulant containing 1.3 × 108 CFU g−1 of Bacillus spp.) to mineral nutrient solutions (MNS) with two salinity levels (0 and 20 mM NaCl). Leaf lettuce plants showed a significant reduction of growth and yield under salt stress, determined by the reduction of biomass, leaf number, and leaf area. Plants showed to be more tolerant to salinity in autumn than in spring. The inhibition of lettuce plant growth due to salt stress was significantly alleviated by the addition of the bacterial biostimulant to the MNS, which had a positive effect on plant growth and fresh and dry biomass accumulation of the unstressed lettuce in both cultivation seasons, and maintained this positive effect in brackish MNS, with similar or even significantly higher values of morphologic, physiologic, and yield parameters than those recorded in control unstressed plants.

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