| 1. |
- Abd El-Daim, Islam Ahmed Moustafa, et al.
(author)
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Bacillus velezensis 5113 Induced Metabolic and Molecular Reprogramming during Abiotic Stress Tolerance in Wheat
- 2019
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Journal article (peer-reviewed)abstract
- Abiotic stresses are main limiting factors for agricultural production around the world. Plant growth promoting rhizobacteria (PGPR) have been shown to improve abiotic stress tolerance in several plants. However, the molecular and physiological changes connected with PGPR priming of stress management are poorly understood. The present investigation aimed to explore major metabolic and molecular changes connected with the ability of Bacillus velezensis 5113 to mediate abiotic stress tolerance in wheat. Seedlings treated with Bacillus were exposed to heat, cold/freezing or drought stress. Bacillus improved wheat survival in all stress conditions. SPAD readings showed higher chlorophyll content in 5113-treated stressed seedlings. Metabolite profiling using NMR and ESI-MS provided evidences for metabolic reprograming in 5113-treated seedlings and showed that several common stress metabolites were significantly accumulated in stressed wheat. Two-dimensional gel electrophoresis of wheat leaves resolved more than 300 proteins of which several were differentially expressed between different treatments and that cold stress had a stronger impact on the protein pattern compared to heat and drought. Peptides maps or sequences were used for database searches which identified several homologs. The present study suggests that 5113 treatment provides systemic effects that involve metabolic and regulatory functions supporting both growth and stress management.
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| 2. |
- Abd El-Daim, Islam Ahmed Moustafa, et al.
(author)
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Identifying potential molecular factors involved in Bacillus amyloliquefaciens 5113 mediated abiotic stress tolerance in wheat
- 2018
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In: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 20, s. 271-279
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Journal article (peer-reviewed)abstract
- Abiotic stressors are main limiting factors for agricultural production around the world. Plant growth-promoting bacteria have been successfully used to improve abiotic stress tolerance in several crops including wheat. However, the molecular changes involved in the improvement of stress management are poorly understood. The present investigation addressed some molecular factors involved in bacterially induced plant abiotic stress responses by identifying differentially expressed genes in wheat (Triticum aestivum) seedlings treated with the beneficial bacterium Bacillus amyloliquefaciens subsp. plantarum UCMB5113 prior to challenge with abiotic stress conditions such as heat, cold or drought. cDNA-AFLP analysis revealed differential expression of more than 200 transcript-derived fragments (TDFs) in wheat leaves. Expression of selected TDFs was confirmed using RT-PCR. DNA sequencing of 31 differentially expressed TDFs revealed significant homology with both known and unknown genes in database searches. Virus-induced gene silencing of two abscisic acid-related TDFs showed different effects upon heat and drought stress. We conclude that treatment with B.amyloliquefaciens 5113 caused molecular modifications in wheat in order to induce tolerance against heat, cold and drought stress. Bacillus treatment provides systemic effects that involve metabolic and regulatory functions supporting both growth and stress management.
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| 3. |
- Abd El-Daim, Islam Ahmed Moustafa, et al.
(author)
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Impact of bacterial priming on some stress tolerance mechanisms and growth of cold stressed wheat seedlings
- 2013
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In: International Journal of Plant Biology. - : MDPI AG. - 2037-0156 .- 2037-0164. ; 4, s. 29-33
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Journal article (peer-reviewed)abstract
- The potential to enhance growth of cold stressed wheat by seed treatment (priming) with the beneficial bacteria Bacillus amyloliquefaciens 5113 and Azospirillum brasilense NO40 were tested. Results showed an improved ability of bacteria-treated seedlings to survive at −5°C up to 12 h. Cold stress increased transcript levels of three stress marker genes and increased activity for the ascorbate-glutathione redox enzymes. However, primed and stressed seedlings generally showed smaller effects on the stress markers correlating with better growth and improved stress tolerance. Bacterial priming to improve crop plant performance at low temperature seems a useful strategy to explore further.
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| 4. |
- Abd El-Daim, Islam Ahmed Moustafa, et al.
(author)
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Improved heat stress tolerance of wheat seedlings by bacterial seed treatment
- 2014
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In: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 379, s. 337-350
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Journal article (peer-reviewed)abstract
- Aim: To investigate if rhizosphere bacteria can improve heat tolerance of wheat. MethodsWheat (Triticum aestivum) seeds of the cultivars Olivin and Sids1 were treated with Bacillus amyloliquefaciens UCMB5113 or Azospirillum brasilense NO40 and young seedlings tested for management of short term heat stress. ResultsBacterial treatment improved heat stress management of wheat. Olivin showed higher heat tolerance than Sids1 both with non-inoculated and inoculated seeds. Heat increased transcript levels of several stress related genes in the leaves, while expression was lower in inoculated plants but elevated compared with the control. Enzymes of the ascorbate-glutathione redox cycle were activated in leaves after heat challenge but showed a lower response in inoculated plants. Metabolite profiling distinguished different treatments dependent on analysis technique with respect to primary and secondary metabolites. Analysis of some plant stress regulatory genes showed that bacterial treatment increased transcript levels while effects of heat treatment varied. Conclusions: The improvement of heat tolerance by bacteria seems associated with reduced generation of reactive oxygen species (and consequently less cell damage), small changes in the metabolome while preactivation of certain heat shock transcription factors seems important. Seed inoculation with beneficial bacteria seems a promising strategy to improve heat tolerance of wheat.
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| 5. |
- Andersson, Derek, et al.
(author)
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Myrosinases from root and leaves of Arabidopsis thaliana have different catalytic properties
- 2009
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In: Phytochemistry. - : Elsevier BV. - 0031-9422 .- 1873-3700. ; 70:11-12, s. 1345-1354
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Journal article (peer-reviewed)abstract
- Myrosinases (EC 3.2.1.147) are beta-thioglucoside glucosidases present in Brassicaceae plants. These enzymes serve to protect plants against pathogens and insect pests by initiating breakdown of the secondary metabolites glucosinolates into toxic products. Several forms of myrosinases are present in plants but the properties and role of different isoenzymes are not well understood. The dicot plant model organism Arabidopsis thaliana seems to contain six myrosinase genes (TGG1-TGG6). In order to compare the different myrosinases, cDNAs corresponding to TGG1 from leaves and TGG4 and TGG5 from roots were cloned and overexpressed in Pichia pastoris. The His-tagged recombinant proteins were purified using affinity chromatography and the preparations were homogenous according to SDS-PAGE analysis. Myrosinase activity was confirmed for all forms and compared with respect to catalytic activity towards the allyl-glucosinolate sinigrin. There was a 22-fold difference in basal activity among the myrosinases. The enzymes were active in a broad pH range, are rather thermostable and active in a wide range of salt concentrations but sensitive to high salt concentrations. The myrosinases showed different activation-inhibition responses towards ascorbic acid with maximal activity around 0.7-1 mM. No activity was registered towards desulphosinigrin and this compound did not inhibit myrosinase activity towards sinigrin. All myrosinases also displayed O-beta-glucosidase activity, although with lower efficiency compared to the myrosinase activity. The differences in catalytic properties among myrosinase isozymes for function in planta are discussed.
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| 6. |
- Asari, Shashidar, et al.
(author)
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Analysis of plant growth-promoting properties of Bacillus amyloliquefaciens UCMB5113 using Arabidopsis thaliana as host plant
- 2017
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In: Planta. - : Springer Science and Business Media LLC. - 0032-0935 .- 1432-2048. ; 245, s. 15-30
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Journal article (peer-reviewed)abstract
- This study showed that Bacillus amyloliquefaciens UCMB5113 colonizing Arabidopsis roots changed root structure and promoted growth implying the usability of this strain as a novel tool to support sustainable crop production.Root architecture plays a crucial role for plants to ensure uptake of water, minerals and nutrients and to provide anchorage in the soil. The root is a dynamic structure with plastic growth and branching depending on the continuous integration of internal and environmental factors. The rhizosphere contains a complex microbiota, where some microbes can colonize plant roots and support growth and stress tolerance. Here, we report that the rhizobacterium Bacillus amyloliquefaciens subsp. plantarum UCMB5113 stimulated the growth of Arabidopsis thaliana Col-0 by increased lateral root outgrowth and elongation and root-hair formation, although primary root elongation was inhibited. In addition, the growth of the above ground tissues was stimulated by UCMB5113. Specific hormone reporter gene lines were tested which suggested a role for at least auxin and cytokinin signaling during rhizobacterial modulation of Arabidopsis root architecture. UCMB5113 produced cytokinins and indole-3-acetic acid, and the formation of the latter was stimulated by root exudates and tryptophan. The plant growth promotion effect by UCMB5113 did not appear to depend on jasmonic acid in contrast to the disease suppression effect in plants. UCMB5113 exudates inhibited primary root growth, while a semi-purified lipopeptide fraction did not and resulted in the overall growth promotion indicating an interplay of many different bacterial compounds that affect the root growth of the host plant. This study illustrates that beneficial microbes interact with plants in root development via classic and novel signals.
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| 7. |
- Asari, Shashidar, et al.
(author)
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Insights into the molecular basis of biocontrol of Brassica pathogens by Bacillus amyloliquefaciens UCMB5113 lipopeptides
- 2017
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In: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 120, s. 551-562
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Journal article (peer-reviewed)abstract
- Background and Aims Certain micro-organisms can improve plant protection against pathogens. The protective effect may be direct, e.g. due to antibiotic compounds, or indirect, by priming of plant defence as induced systemic resistance (ISR). The plant growth-promoting rhizobacterium Bacillus amyloliquefaciens UCMB5113 shows potential for disease management of oilseed rape. To investigate the mode of action of this protection, especially in relation to jasmonic acid-dependent ISR, Bacillus UCMB5113 was tested with Arabidopsis thaliana mutants and several important fungal pathogens of Brassica species.Methods Secreted lipopeptide fractions from Bacillus UCMB5113, together with synthetic peptide mimics, were evaluated for their effects on fungal phytopathogens and A. thaliana. The structures of secreted lipopeptides were analysed using mass spectrometry. Plant mutants and reporter lines were used to identify signalling steps involved in disease suppression by lipopeptides.Key Results In plate tests Bacillus UCMB5113 and lipopeptide extracts suppressed growth of several fungal pathogens infecting Brassica plants. Separation of secreted lipopeptides using reversed-phase high-performance liquid chromatography revealed several fractions that inhibited fungal growth. Analysis by mass spectrometry identified the most potent compounds as novel linear forms of antifungal fengycins, with synthetic peptide mimics confirming the biological activity. Application of the lipopeptide extracts on Arabidopsis roots provided systemic protection against Alternaria brassicicola on leaves. Arabidopsis signalling mutants and PDF1.2 and VSP2 promoter-driven GUS lines indicated that the lipopeptide fraction involved jasmonic-acid-dependent host responses for suppression of fungal growth indicative of ISR.Conclusions The ability of Bacillus UCMB5113 to counteract pathogens using both antagonistic lipopeptides and through ISR provides a promising tool for sustainable crop production.
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| 8. |
- Asari, Shashidar, et al.
(author)
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Multiple effects of Bacillus amyloliquefaciens volatile compounds: plant growth promotion and growth inhibition of phytopathogens
- 2016
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In: FEMS Microbiology Ecology. - : Oxford University Press (OUP). - 0168-6496 .- 1574-6941. ; 92
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Journal article (peer-reviewed)abstract
- Biotic interactions through volatile organic compounds (VOC) are frequent in nature. This investigation aimed to study the role of Bacillus VOC for the beneficial effects on plants observed as improved growth and pathogen control. Four Bacillus amyloliquefaciens subsp. plantarum strains were screened for VOC effects on Arabidopsis thaliana Col-0 seedlings and Brassica fungal phytopathogens. VOC from all four Bacillus strains could promote growth of Arabidopsis plants resulting in increased shoot biomass but the effects were dependent on the growth medium. Dose response studies with UCMB5113 on MS agar with or without root exudates showed significant plant growth promotion even at low levels of bacteria. Bacillus VOC antagonized growth of several fungal pathogens in vitro. However, the plant growth promotion efficacy and fungal inhibition potency varied among the Bacillus strains. VOC inhibition of several phytopathogens indicated efficient microbial antagonism supporting high rhizosphere competence of the Bacillus strains. GC-MS analysis identified several VOC structures where the profiles differed depending on the growth medium. The ability of Bacillus strains to produce both volatile and soluble compounds for plant growth promotion and disease biocontrol provides examples of rhizosphere microbes as an important ecosystem service with high potential to support sustainable crop production.
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| 9. |
- Ayuke, Fredrick, et al.
(author)
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Effects of biocontrol bacteria and earthworms on the severity of Alternaria brassicae disease and the growth of oilseed rape plants (Brassica napus)
- 2017
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In: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 117-118, s. 63-69
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Journal article (peer-reviewed)abstract
- Biological control of plant diseases through the addition of microbial biocontrol agents and the promotion of earthworms can be an environmentally friendly alternative to the chemical control of plant diseases. However, possible risks with biocontrol agents and their interactions with earthworms and other soil biota have not been well studied. The aim of this study was to assess whether the beneficial bacterium Bacillus amyloliquefaciens and the earthworms Aporrectodea caliginosa or Aporrectodea longa could reduce disease in oilseed rape (Brassica napus) challenged with the pathogen Alternaria brassicae. Plant growth and productivity were measured as plant survival, height, biomass, and flower development as well as disease index. A second objective was to assess whether the presence of the bacterium at high concentrations would influence the survival, growth, and reproduction of the earthworms. One outdoor and one greenhouse experiment were performed with Br. napus plants challenged with AL brassicae inoculated to the plant leaves in the presence or absence of Bacillus amyloliquefaciens inoculated to the root environment and in the presence or absence of earthworms (Ap. caliginosa or Ap. longa) added to the soil. All treatments were replicated three times. In the outdoor experiment, inoculation with AL brassicae reduced the growth of plants and the addition of Ap. caliginosa increased plant height. In the greenhouse experiment, pairwise comparisons of plants challenged with AL brassicae showed that treatment with B. amyloliquefaciens led to significantly lower disease index than the treatment with Ap. caliginosa plus B. amyloliquefaciens, while other treatments had intermediate disease indices. The addition of AL brassicae or B. amyloliquefaciens increased the survival and mass increment of Ap. caliginosa as a main effect when used separately but not when used in combination.This study did not give any clear indication of the usefulness of B. amyloliquefaciens for biocontrol of plant pathogens such as AL brassicae when growing plants in natural soil. In addition, no significantly positive effects from the tested earthworm species were seen.
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| 10. |
- Bejai, Sarosh, et al.
(author)
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A novel role of PR2 in abscisic acid (ABA) mediated, pathogen-induced callose deposition in Arabidopsis thaliana
- 2013
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In: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 200, s. 1187-1199
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Journal article (peer-reviewed)abstract
- Pathogenesis-related protein 2 (PR2) is known to play a major role in plant defense andgeneral stress responses. Resistance against the fungal pathogen Leptosphaeria maculans inArabidopsis requires abscisic acid (ABA), which promotes the deposition of callose, a b-1,3-glucan polymer. Here, we examined the role of PR2 in callose deposition in relation to ABAtreatment and challenge with L. maculans and Pseudomonas syringae. Characterization of PR2-overexpressing plants and the knockout line indicated that PR2negatively affects callose deposition. Recombinant PR2 purified from Pichia pastoris showedcallose-degrading activity, and a considerable reduction in the callose-degrading activity wasobserved in the leaf extract of the PR2 knockout line compared with the wild-type. ABA pretreatment before challenge with L. maculans concomitantly repressed PR2 andenhanced callose accumulation. Likewise, overexpression of an ABA biosynthesis geneNCED3 resulted in reduced PR2 expression and increased callose deposition. We propose that ABA promotes callose deposition through the transcriptional repression ofPR2 in Arabidopsis challenged by L. maculans and P. syringae. Callose by itself is likely to actantagonistically on salicylic acid (SA) defense signaling, suggesting that PR2 may function as amodulator of callose- and SA-dependent defense responses.
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