Nature and role of root exudates: Efficacy in bioremediation

Shukla, Keshav Prasad; Sharma, Shivesh; Singh, Nand Kumar; Singh, Varsha; Tiwari, K. C.; Singh, Sphoorti

doi:10.5897/ajb10.2552

Cited by 30 publications

(12 citation statements)

References 75 publications

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“…A significant improvement in plant height signified the imperative role of co-application of E. cloacae and A. xylosoxidans with TWBC over sole application of TWBC and control. Roots secrete organic acids, sugars, vitamins, phytosiderophores, nucleosides amino acids and mucilage, that attract PGPRs and resulted in better colonization of PGPRs, uptake of water and nutrients [85][86][87]. However, it is well documented that the colonization of PGPR is also improved when PGPR are inoculated with biochar [47].…”

Section: Discussionmentioning

confidence: 99%

Drought Stress Alleviation by ACC Deaminase Producing Achromobacter xylosoxidans and Enterobacter cloacae, with and without Timber Waste Biochar in Maize

et al. 2020

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The high consumption of water in industries, domestic areas and increasing earth temperature are major hurdles for the optimization of maize yield. Being the third most widely cultivated cereal crop, improvement in maize yield is a big challenge under the limited availability of irrigation. As the water requirement for maize cultivation is high, it is time to introduce technologies that can mitigate drought stress and are environmentally friendly. The inoculation of rhizobacteria with ‘1-aminocyclopropane-1-carboxylate deaminase’ (ACCD) can play an imperative role in that regard by decreasing stress ethylene in plants. Biochar (BC) can also alleviate drought stress. Therefore, a field study was conducted, to examine the single and combined application of drought-tolerant plant-growth-promoting rhizobacteria (PGPRs) Achromobacter xylosoxidans and Enterobacter cloacae, with 15 Mg ha−1 of timber waste biochar (TWBC) at normal irrigation = 16 irrigations, mild drought = 14 irrigations and severe drought = 12 irrigation for maize cultivation. A significant improvement in shoot dry weight (28%), 1000-grains weight (19%), grain yield (27%), concentrations of N (43%), P (92%) and K (71%) in grains, rate of photosynthesis (33%), transpiration rate (55%), stomatal conductance (104%), chlorophyll A (33%), chlorophyll B (62%) and total chlorophyll (45%) of maize was noted under drought stress where E. cloacae + TWBC was applied. Likewise, the application of A. xylosoxidans + TWBC also significantly enhanced the plant height (24%) and cob length (9%) of maize under drought stress. In conclusion, E. cloacae is more effective than A. xylosoxidans, with 15 Mg ha−1 TWBC to increase maize yield under drought stress, due to the potential of higher ‘1-aminocyclopropane-1-carboxylate’ (ACC)-deaminase synthesis, better nutrient solubilization and indole acetic acid (IAA) production.

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Section: Discussionmentioning

confidence: 99%

Drought Stress Alleviation by ACC Deaminase Producing Achromobacter xylosoxidans and Enterobacter cloacae, with and without Timber Waste Biochar in Maize

et al. 2020

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“…The solutions were distributed over the plates according to a complete randomized block design. Shukla et al, 2011;Iannucci et al, 2013;Ray et al, 2018;Zhalnina et al, 2018 Sigma-Aldrich, H36001 Syringic acid 0.917 0.1 Shukla et al, 2011;Iannucci et al, 2013;Zhalnina et al, 2018 Sigma-Aldrich, 86230 For each compound are displayed: the concentration used for preparing the artificial exudates (AE) solution, the amount of added carbon per gram of sand, references to literature reporting the presence of each compound in root exudates and the product used in this study.…”

Section: Setup Of Two-compartment Rhizosphere Simulation Microcosmsmentioning

confidence: 99%

Evaluation of Phenolic Root Exudates as Stimulants of Saptrophic Fungi in the Rhizosphere

et al. 2021

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The rhizosphere microbial community of crop plants in intensively managed arable soils is strongly dominated by bacteria, especially in the initial stages of plant development. In order to establish more diverse and balanced rhizosphere microbiomes, as seen for wild plants, crop variety selection could be based on their ability to promote growth of saprotrophic fungi in the rhizosphere. We hypothesized that this can be achieved by increasing the exudation of phenolic acids, as generally higher fungal abundance is observed in environments with phenolic-rich inputs, such as exudates of older plants and litter leachates. To test this, a rhizosphere simulation microcosm was designed to establish gradual diffusion of root exudate metabolites from sterile sand into arable soil. With this system, we tested the fungus-stimulating effect of eight phenolic acids alone or in combination with primary root metabolites. Ergosterol-based fungal biomass measurements revealed that most phenolic acids did not increase fungal abundance in the arable soil layer. These results were supported by comparison of fungal biomass in the rhizosphere of wild type Arabidopsis thaliana plants and mutants with altered phenolic acid metabolism. Salicylic acid was the only phenolic acid that stimulated a higher fungal biomass in the arable soil layer of microcosms, but only when combined with a background of primary root metabolites. However, such effect on rhizosphere fungi was not confirmed for a salicylic acid-impaired A. thaliana mutant. For three phenolic acid treatments (chlorogenic acid, salicylic acid, vanillic acid) fungal and bacterial community compositions were analyzed using amplicon sequencing. Despite having little effect on fungal biomass, phenolic acids combined with primary metabolites promoted a higher relative abundance of soil-borne fungi with the ability to invade plant roots (Fusarium, Trichoderma and Fusicolla spp.) in the simulated rhizosphere. Bacterial community composition was also affected by these phenolic acids. Although this study indicates that phenolic acids do not increase fungal biomass in the rhizosphere, we highlight a potential role of phenolic acids as attractants for root-colonizing fungi.

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“…The main physiological and biochemical characteristics of each strain are shown in (Keshav et al, 2013). These organic acids have hydroxyl and carboxyl groups, which can chelate the cations that bind to phosphates, resulting in the conversion of insoluble phosphorus to its soluble form (Mahanty et al, 2017).…”

Section: Physiological and Biochemical Characteristics Of Psbsmentioning

confidence: 99%

Screening, Identification and Growth Promotion Ability of Phosphate Solubilizing Bacteria from Soybean Rhizosphere under Maize-Soybean Intercropping Systems

Wang¹,

Ck²,

Song³

et al. 2020

Preprint

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The solubilization and mineralization of phosphorus by phosphate-solubilizing bacteria (PSB) is one of the most important bacterial physiological characteristics in the soil biogeochemical cycle. Through the isolation and screening of microorganisms in the rhizosphere soil of intercropped soybean in Ya’an, Renshou and Chongzhou, 9 PSBs with high phosphorus solubilizing ability were identified. It mainly belongs to Bacillus and Pseudomonas. The phosphate solubility of Bacillus aryabhattai B8W22 is as high as 388.62 µg·mL-1. The physiological and biochemical characteristics of each strain showed that it can secrete organic acids such as formic acid, acetic acid lactic acid and pyruvic acid. In addition, all strains can produce indole acetic acid and siderophores that promote plant growth. Seed germination experiments also showed that the phosphorus solubilizing bacteria isolated in this research have a certain ability to promote plant growth.IMPRTANCEBacillus aryabhattai from rhizosphere soil of intercropped soybean has high phosphate-solubilizing ability, could produce indole acetic acid and siderophores that promote plant growth, and are of great significance in reducing the application of chemical phosphate fertilizers and promoting sustainable agricultural development.

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Nature and role of root exudates: Efficacy in bioremediation

Cited by 30 publications

References 75 publications

Drought Stress Alleviation by ACC Deaminase Producing Achromobacter xylosoxidans and Enterobacter cloacae, with and without Timber Waste Biochar in Maize

Drought Stress Alleviation by ACC Deaminase Producing Achromobacter xylosoxidans and Enterobacter cloacae, with and without Timber Waste Biochar in Maize

Evaluation of Phenolic Root Exudates as Stimulants of Saptrophic Fungi in the Rhizosphere

Screening, Identification and Growth Promotion Ability of Phosphate Solubilizing Bacteria from Soybean Rhizosphere under Maize-Soybean Intercropping Systems

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