Efficacy of rhizobacterial exopolysaccharides in improving plant growth, physiology, and soil properties

Dar, Abubakar; Zahir, Zahir Ahmad; Iqbal, Muhammad Asif; Mehmood, Atif; Javed, Aisha; Hussain, Azhar; Bushra,; Ahmad, Maqshoof

doi:10.1007/s10661-021-09286-6

Cited by 17 publications

(9 citation statements)

References 54 publications

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“…Our findings are similar to the findings of Hussain et al [59], who stated that the combination of different organic carrier materials with a consortium of PGPR improve the quality, growth, and output of maize grains. Moreover, this growth enhancement might be due to the PGPR strains' possession of growth-promoting traits, which, when applied with organic carriers as a consortium, might synergize for a growth-promoting impact on spinach, as described for maize in Dar et al [60].…”

Section: Discussionmentioning

confidence: 99%

The Effect of Different Carrier Materials on the Growth and Yield of Spinach under Pot and Field Experimental Conditions

et al. 2022

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Long-term use of chemical fertilizers is affecting the environment, soil quality, and biodiversity. Organic agriculture is gaining global attention by using microbial-based biofertilizers. Carriers protect microbes by providing nutrition, energy, and suitable conditions for their survival while entering the natural environments. The purpose of this study was to evaluate the ability of different carrier materials to enhance the yield and the quality of spinach and to select the best carrier material for spinach biofertilizer. Three pre-isolated and characterized bacterial strains (AN-35, ZM-27, and ZM-63) were tested for their compatibility and used in this experiment through seed inoculation with organic carriers, i.e., compost, peat, press mud, biochar, and charcoal. A pot experiment and a field experiment were conducted to evaluate the efficacy of different organic carriers. The results of the pot study showed a significant increase in spinach growth, i.e., shoot length (25%), shoot fresh weight (24%), root length (25%), and root fresh weight (29%), spinach nutrition, i.e., nitrogen (18%), phosphorus (22%), potassium (15%), iron (17%), and zinc (14%), spinach physiology, i.e., relative water content (27%), chlorophyll content (9%), and the membrane stability index (28%) under peat coated treatments with 24% more soil microbial populations compared to the control. Similarly, in the field experiment, peat coating significantly enhanced spinach growth, i.e., shoot length (29%), shoot fresh weight (23%), root length (16%), and root fresh weight (24.7%), spinach nutrition, i.e., nitrogen (16%), phosphorus (19%), potassium (15%), iron (17%), and zinc (23%), spinach physiology, i.e., relative water content (28%), chlorophyll content (13%) and the membrane stability index (32%), and spinach yield per hectare (30%), as well as producing 20% higher soil microbial populations. From these results, it is concluded that peat is a good carrier material for biofertilizer production as it not only enhances crop production but also the microbial number, in addition to improving soil quality.

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Section: Discussionmentioning

confidence: 99%

The Effect of Different Carrier Materials on the Growth and Yield of Spinach under Pot and Field Experimental Conditions

et al. 2022

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“…Furthermore, experiments involving the growth of EH143 on colorimetric CAS‐Agar media indicated that EH143 can produce siderophores; the genes involved in siderophore production, yfiZ and yfhA were certified in WGS data of EH143 (Figure 1D). Similarly, different plant growth‐promoting bacteria have been shown to produce exopolysaccharides (EPS) that improve plant growth, physiology, and soil attributes 55 . EPS has been shown to enhance plant resistance to different abiotic stresses including drought by increasing the water‐holding capacity, antioxidant activation, osmoprotectants, and biofilm formation at the root‐soil interface 56 .…”

Section: Resultsmentioning

confidence: 99%

“…Similarly, different plant growthpromoting bacteria have been shown to produce exopolysaccharides (EPS) that improve plant growth, physiology, and soil attributes. 55 EPS has been shown to enhance plant resistance to different abiotic stresses including drought by increasing the water-holding capacity, antioxidant activation, osmoprotectants, and biofilm formation at the root-soil interface. 56 EPS production by PGPB is determined via the congo-red (CR) assay.…”

Section: Isolation and Identification Of B Safensis Eh143mentioning

confidence: 99%

Novel melatonin‐producing Bacillus safensis EH143 mitigates salt and cadmium stress in soybean

Kwon,

Adhikari,

Imran

et al. 2024

Journal of Pineal Research

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Recently, microorganism and exogenous melatonin application has been recognized as an efficient biological tool for enhancing salt tolerance and heavy metal detoxification in agriculture crops. Thus, the goal of this study was to isolate and evaluate a novel melatonin‐producing plant growth promoting bacterium. With high‐throughput whole genome sequencing, phytohormone measurements, expression profiling, and biochemical analysis, we can identify a novel PGPB that produces melatonin and unravel how it promotes soybean growth and development and protects against salt and Cd stress. We identify the melatonin synthesis pathway (tryptophan→tryptamine→serotonin melatonin) of the halotolerant (NaCl > 800 mM) and heavy metal‐resistant (Cd >3 mM) rhizobacterium Bacillus safensis EH143 and use it to treat soybean plants subjected to Cd and NaCl stresses. Results show that EH143 will highly bioaccumulate heavy metals and significantly improve P and Ca2+ uptake and the K+/Na+ (93%↑under salt stress) ratio while reducing Cd uptake (49% under Cd stress) in shoots. This activity was supported by the expression of the ion regulator HKT1, MYPB67, and the calcium sensors CDPK5 and CaMK1 which ultimately led to increased plant growth. EH143 significantly decreased ABA content in shoots by 13%, 20%, and 34% and increased SA biosynthesis in shoots by 14.8%, 31%, and 48.2% in control, salt, and Cd‐treated plants, upregulating CYP707A1 and CYP707A2 and PAL1 and ICS, respectively. The melatonin content significantly decreased along with a reduced expression of ASMT3 following treatment with EH143; moreover, reduced expression of peroxidase (POD) and superoxide dismutase (SOD) by 134.5% and 39% under salt+Cd stress, respectively and increased level of total amino acids were observed. Whole‐genome sequencing and annotation of EH143 revealed the presence of the melatonin precursor tryptophan synthase (trpA, trpB, trpS), metal and other ion regulators (Cd: cadA, potassium: KtrA and KtrB, phosphate: glpT, calcium: yloB, the sodium/glucose cotransporter: sgIT, and the magnesium transporter: mgtE), and enzyme activators (including the siderophore transport proteins yfiZ and yfhA, the SOD sodA, the catalase katA1, and the glutathione regulator KefG) that may be involved in programming the plant metabolic system. As a consequence, EH143 treatment significantly reduced the contents of lipid peroxidation (O2‐, MDA, and H2O2) up to 69%, 46%, and 29% in plants under salt+Cd stress, respectively. These findings suggest that EH143 could be a potent biofertilizer to alleviate NaCl and Cd toxicity in crops and serve as an alternative substitute for exogenous melatonin application.

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“…While a comprehensive understanding of the direct impact of EPSs on plant physiology to improve drought stress is not absolute, Naseem and Bano [ 43 ] suggested that diverse functional groups of EPSs trigger different plant antioxidant mechanisms to alleviate drought stress. The flocculating property of EPSs allows the aggregation of primary soil particles, enabling the stabilization of the soil structure and the improvement of soil physical properties such as porosity and bulk density [ 44 ]. Due to these characteristics, EPS-producing PGPRs, when associated with plants, play a crucial role in alleviating abiotic stress and are widely used for bioremediation.…”

Section: Microbial Exudates and Their Compositionmentioning

confidence: 99%

Microbial Exudates as Biostimulants: Role in Plant Growth Promotion and Stress Mitigation

Ansari,

Devi,

Sarkar

et al. 2023

JoX

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Microbes hold immense potential, based on the fact that they are widely acknowledged for their role in mitigating the detrimental impacts of chemical fertilizers and pesticides, which were extensively employed during the Green Revolution era. The consequence of this extensive use has been the degradation of agricultural land, soil health and fertility deterioration, and a decline in crop quality. Despite the existence of environmentally friendly and sustainable alternatives, microbial bioinoculants encounter numerous challenges in real-world agricultural settings. These challenges include harsh environmental conditions like unfavorable soil pH, temperature extremes, and nutrient imbalances, as well as stiff competition with native microbial species and host plant specificity. Moreover, obstacles spanning from large-scale production to commercialization persist. Therefore, substantial efforts are underway to identify superior solutions that can foster a sustainable and eco-conscious agricultural system. In this context, attention has shifted towards the utilization of cell-free microbial exudates as opposed to traditional microbial inoculants. Microbial exudates refer to the diverse array of cellular metabolites secreted by microbial cells. These metabolites enclose a wide range of chemical compounds, including sugars, organic acids, amino acids, peptides, siderophores, volatiles, and more. The composition and function of these compounds in exudates can vary considerably, depending on the specific microbial strains and prevailing environmental conditions. Remarkably, they possess the capability to modulate and influence various plant physiological processes, thereby inducing tolerance to both biotic and abiotic stresses. Furthermore, these exudates facilitate plant growth and aid in the remediation of environmental pollutants such as chemicals and heavy metals in agroecosystems. Much like live microbes, when applied, these exudates actively participate in the phyllosphere and rhizosphere, engaging in continuous interactions with plants and plant-associated microbes. Consequently, they play a pivotal role in reshaping the microbiome. The biostimulant properties exhibited by these exudates position them as promising biological components for fostering cleaner and more sustainable agricultural systems.

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Efficacy of rhizobacterial exopolysaccharides in improving plant growth, physiology, and soil properties

Cited by 17 publications

References 54 publications

The Effect of Different Carrier Materials on the Growth and Yield of Spinach under Pot and Field Experimental Conditions

The Effect of Different Carrier Materials on the Growth and Yield of Spinach under Pot and Field Experimental Conditions

Novel melatonin‐producing Bacillus safensis EH143 mitigates salt and cadmium stress in soybean

Microbial Exudates as Biostimulants: Role in Plant Growth Promotion and Stress Mitigation

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