Effects of endophytes inoculation on rhizosphere and endosphere microecology of Indian mustard (Brassica juncea) grown in vanadium-contaminated soil and its enhancement on phytoremediation

Wang, Liang; Lin, Hai; Dong, Yingbo; Li, Bing; He, Yinhai

doi:10.1016/j.chemosphere.2019.124891

Cited by 81 publications

(28 citation statements)

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“…It was reported in the literature that plant growth-promoting rhizobacteria (PGPR) can enhance the growth of the plants and improve the soil conditions. It was also documented that when plants having heavy metal accumulation abilities were grown for phytoremediation purposes they showed less biomass and had a very slow growth rate [27]. Research studies revealed that rhizobacterial strains having the characteristics of siderophore production, phosphate solubilization, organic acid synthesis, ACC deaminase synthesis, and hydrogen cyanide production abilities have the potential to improve the growth of the plant and can enhance metal uptake in contaminated soil [28].…”

Section: Discussionmentioning

confidence: 99%

Role of Bacillus cereus in Improving the Growth and Phytoextractability of Brassica nigra (L.) K. Koch in Chromium Contaminated Soil

et al. 2021

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Plant growth-promoting rhizobacteria (PGPR) mediate heavy metal tolerance and improve phytoextraction potential in plants. The present research was conducted to find the potential of bacterial strains in improving the growth and phytoextraction abilities of Brassica nigra (L.) K. Koch. in chromium contaminated soil. In this study, a total of 15 bacterial strains were isolated from heavy metal polluted soil and were screened for their heavy metal tolerance and plant growth promotion potential. The most efficient strain was identified by 16S rRNA gene sequencing and was identified as Bacillus cereus. The isolate also showed the potential to solubilize phosphate and synthesize siderophore, phytohormones (indole acetic acid, cytokinin, and abscisic acid), and osmolyte (proline and sugar) in chromium (Cr+3) supplemented medium. The results of the present study showed that chromium stress has negative effects on seed germination and plant growth in B. nigra while inoculation of B. cereus improved plant growth and reduced chromium toxicity. The increase in seed germination percentage, shoot length, and root length was 28.07%, 35.86%, 19.11% while the fresh and dry biomass of the plant increased by 48.00% and 62.16%, respectively, as compared to the uninoculated/control plants. The photosynthetic pigments were also improved by bacterial inoculation as compared to untreated stress-exposed plants, i.e., increase in chlorophyll a, chlorophyll b, chlorophyll a + b, and carotenoid was d 25.94%, 10.65%, 20.35%, and 44.30%, respectively. Bacterial inoculation also resulted in osmotic adjustment (proline 8.76% and sugar 28.71%) and maintained the membrane stability (51.39%) which was also indicated by reduced malondialdehyde content (59.53% decrease). The antioxidant enzyme activities were also improved to 35.90% (superoxide dismutase), 59.61% (peroxide), and 33.33% (catalase) in inoculated stress-exposed plants as compared to the control plants. B. cereus inoculation also improved the uptake, bioaccumulation, and translocation of Cr in the plant. Data showed that B. cereus also increased Cr content in the root (2.71-fold) and shoot (4.01-fold), its bioaccumulation (2.71-fold in root and 4.03-fold in the shoot) and translocation (40%) was also high in B. nigra. The data revealed that B. cereus is a multifarious PGPR that efficiently tolerates heavy metal ions (Cr+3) and it can be used to enhance the growth and phytoextraction potential of B. nigra in heavy metal contaminated soil.

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Section: Discussionmentioning

confidence: 99%

Role of Bacillus cereus in Improving the Growth and Phytoextractability of Brassica nigra (L.) K. Koch in Chromium Contaminated Soil

et al. 2021

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“…These bacteria have high drought stress tolerance and most of them promote plant growth [53][54][55]. Bacillus species are also effective biocontrol bacteria [56]. Pseudarthrobacter and Sporocytophaga e ciently degrade cellulose, crude oil, and multibenzene compounds [57,58].…”

Section: Discussionmentioning

confidence: 99%

Variation of soil microbiome in licorice rhizosphere driven with inoculating dark septate endophytes under drought stress

He¹,

Wang²,

Hou³

et al. 2020

Preprint

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BackgroundDark septate endophytes (DSE) are facultative biotrophic ascomycetes that colonize plant roots either alone or with arbuscular mycorrhizal (AM) fungi. DSE may provide nutrients to their plant hosts and help them adapt to various abiotic and biotic stresses. DSE inoculation under drought stress increased the biomass, root exudates, and AM fungi in the licorice (Glycyrrhiza uralensis Fisch.) rhizosphere. We conducted a pot experiment to establish whether the responses of licorice to DSE inoculation under drought stress are caused by changes in the rhizosphere microbiome. Each pot was inoculated with either Acrocalymma vagum or Paraboeremia putaminum. One set of pots was inoculated with a sterile culture medium. All three DSE-treated and uninoculated pots were subjected either to a well-watered (70% field water capacity, FWC) or drought stress (30% FWC) water regime. Rhizosphere microbiome compositions were measured by Illumina MiSeq sequencing of the 16S and ITS2 rRNA genes.ResultsIn total, 1,278 fungal and 1,583 bacterial operational taxonomic units (OUTs) were obtained at a 97% sequence similarity level. Ascomycota were the predominant fungi and Proteobacteria, Actinobacteria, Chloroflexi and Firmicutes were the predominant bacteria. DSE inoculation and water regime significantly influenced the rhizosphere microbiome composition. However, the effects of DSE on the fungal community were greater than those on the bacterial community. Paraboeremia putaminum exerted a stronger impact on the licorice rhizosphere microbiome than Acrocalymma vagum under drought stress. The observed changes in edaphic factors (water condition, soil organic matter, available N, available P, and available K) caused by DSE inoculation could be explained by the variations in rhizosphere microbiome composition. A network analysis indicated that DSE inoculation augmented the relative abundance of beneficial symbiotrophic fungi and growth-promoting bacteria but diminished the relative abundance of pathogens in the licorice rhizosphere.ConclusionsThe present study showed that the licorice rhizosphere microbial community differed between the DSE-inoculated and uninoculated plants. DSE had a stronger influence on the fungal than on the bacterial rhizosphere community under drought stress. These give us the guidance to develop biofertilizers with DSE consortia to enhance the cultivation of medicinal plants by shaping soil microbial community structure in dryland agriculture.

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“…Researchers have therefore explored possible methods of increasing remediation efficiency, including effective agronomic practices ( Hamid et al, 2018 , 2019 ; Leite and Monteiro, 2019 ; Wu et al, 2020c ), genetic engineering technology ( Zhang et al, 2014 ; Feng et al, 2018 ), and inoculation with microbes ( Jian et al, 2019 ; Tao et al, 2020 ; Wu et al, 2020b ). Among these technologies, we have focused on plant–microbial remediation due to its low cost and high efficiency for enhancing phytoremediation ( Wang et al, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

“…Microbes such as plant-growth-promoting bacteria ( Guo et al, 2020 ; Wu et al, 2020a ), endophytes ( Santoyo et al, 2016 ; Wood et al, 2016 ; Ma et al, 2017 ; Wang et al, 2020 ), and ectomycorrhiza ( Coninx et al, 2017 ; Szuba et al, 2017 ) can increase the phytoremediation of heavy metals in contaminated soil ( Ma et al, 2016 ; Santoyo et al, 2016 ; Wood et al, 2016 ). Possible mechanisms include stimulation of plant growth through biosynthesis of phytohormones and increasing plant chlorophyll content ( Babu et al, 2015 ; Gang et al, 2018 ), promoting the nutrient cycle through production of siderophores, nitrogen fixation, and solubilization of phosphorus ( Ma et al, 2017 ; Lin et al, 2018 ; Wang L. et al, 2018 ; Wang Q. et al, 2018 ), and promoting heavy-metal tolerance and the expression of some metal-transporter genes in inoculated plants ( Chen et al, 2014 ; Pan et al, 2016 , 2017 ).…”

Section: Introductionmentioning

confidence: 99%

“…By contrast, heavy-metal-tolerant indigenous rhizosphere microbes are better adapted to the environment. The mechanism of promotion phytoremediation after inoculation remains unclear, and has been explored indirectly in most previous studies ( Tao et al, 2020 ; Wang et al, 2020 ). Microbes usually affect phytoremediation through their extracellular metabolites.…”

Section: Introductionmentioning

confidence: 99%

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Inoculation With Indigenous Rhizosphere Microbes Enhances Aboveground Accumulation of Lead in Salix integra Thunb. by Improving Transport Coefficients

et al. 2021

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The application of plant–microbial remediation of heavy metals is restricted by the difficulty of exogenous microbes to form large populations and maintain their long-term remediation efficiency. We therefore investigated the effects of inoculation with indigenous heavy-metal-tolerant rhizosphere microbes on phytoremediation of lead (Pb) by Salix integra. We measured plant physiological indexes and soil Pb bioavailability and conducted widespread targeted metabolome analysis of strains to better understand the mechanisms of enhance Pb accumulation. Growth of Salix integra was improved by both single and co-inoculation treatments with Bacillus sp. and Aspergillus niger, increasing by 14% in co-inoculated plants. Transfer coefficients for Pb, indicating mobility from soil via roots into branches or leaves, were higher following microbial inoculation, showing a more than 100% increase in the co-inoculation treatment over untreated plants. However, Pb accumulation was only enhanced by single inoculation treatments with either Bacillus sp. or Aspergillus niger, being 10% greater in plants inoculated with Bacillus sp. compared with uninoculated controls. Inoculation mainly promoted accumulation of Pb in aboveground plant parts. Superoxide dismutase and catalase enzyme activities as well as the proline content of inoculated plants were enhanced by most treatments. However, soil urease and catalase activities were lower in inoculated plants than controls. Proportions of acid-soluble Pb were 0.34 and 0.41% higher in rhizosphere and bulk soil, respectively, of plants inoculated with Bacillus sp. than in that of uninoculated plants. We identified 410 metabolites from the microbial inoculations, of which more than 50% contributed to heavy metal bioavailability; organic acids, amino acids, and carbohydrates formed the three major metabolite categories. These results suggest that both indigenous Bacillus sp. and Aspergillus niger could be used to assist phytoremediation by enhancing antioxidant defenses of Salix integra and altering Pb bioavailability. We speculate that microbial strains colonized the soil and plants at the same time, with variations in their metabolite profiles reflecting different living conditions. We also need to consider interactions between inocula and the whole microbial community when applying microbial inoculation to promote phytoremediation.

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Effects of endophytes inoculation on rhizosphere and endosphere microecology of Indian mustard (Brassica juncea) grown in vanadium-contaminated soil and its enhancement on phytoremediation

Cited by 81 publications

References 54 publications

Role of Bacillus cereus in Improving the Growth and Phytoextractability of Brassica nigra (L.) K. Koch in Chromium Contaminated Soil

Role of Bacillus cereus in Improving the Growth and Phytoextractability of Brassica nigra (L.) K. Koch in Chromium Contaminated Soil

Variation of soil microbiome in licorice rhizosphere driven with inoculating dark septate endophytes under drought stress

Inoculation With Indigenous Rhizosphere Microbes Enhances Aboveground Accumulation of Lead in Salix integra Thunb. by Improving Transport Coefficients

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