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    Molecular Characterization of the Plant Growth Promoting Bacterium Enterobacter sp. SA187 upon Contact with Arabidopsis thaliana

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    Wiam+Alsharif+Master+Thesis+Final.pdf
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    Description:
    Wiam Alsharif Master Thesis Final
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    Type
    Thesis
    Authors
    Alsharif, Wiam cc
    Advisors
    Hirt, Heribert cc
    Committee members
    Arold, Stefan T. cc
    Blilou, Ikram cc
    Program
    Bioscience
    KAUST Department
    Biological and Environmental Sciences and Engineering (BESE) Division
    Date
    2018-05
    Embargo End Date
    2019-05-08
    Permanent link to this record
    http://hdl.handle.net/10754/627801
    
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    Show full item record
    Access Restrictions
    At the time of archiving, the student author of this thesis opted to temporarily restrict access to it. The full text of this thesis became available to the public after the expiration of the embargo on 2019-05-08.
    Abstract
    Salt stress is a severe environmental challenge in agriculture, limiting the quality and productivity of the crops around the globe. Plant growth promoting rhizobacteria (PGPR) is proposed as a friendly solution to overcome those challenges. The desert plant endophytic bacterium, Enterobacter sp. SA187 has shown plant growth promotion and salt stress tolerance beneficial effect on the model plant Arabidopsis thaliana in vitro as well as under the field conditions on different crops. SA187 has a distinguished morphology of yellow colonies (SA187Y) that could be due to carotenoid biosynthesis. However, the bacteria tend to lose the yellow color upon incubation with the plants and the colonies turn to white (SA187W). In comparison to SA187Y, SA187W shows 50% reduction on the beneficial impact on A. thaliana fresh and dry weight of root and shoot system. By counting the CFU/plant, we showed that SA187Y and SA187W both have similar colonization rate in both shoots and roots. Under non-salt conditions, optimal bacterial colonization was observed on day 8 after inocubation, however, under the salt stress condition, the optimal colonization was observed at day 4. Moreover, during the time period of the incubation of the SA187Y with the plants, there was a consistent noticeable loss of the yellow color of the colonies. This change in color is only observed eight days after transfer and the number of white colonies increases with the increase of the incubation time. In addition, SA187W was GFP-tagged by Tn7 transposon system and visualized by confocal laser scanning microscopy. The SA187W-GFP colonies have shown a similar colonization pattern as SA187Y-GFP, bacteria were colonizing the differentiation zone and cell elongation zone in the roots. Finally, the gene expression of the carotenoid biosynthesis pathways genes in SA187Y showed an overall higher gene expression compared to SA187W. In conclusion, the color loss seems to affect the beneficial impact of the bacteria on plants. However, the reduced beneficial impact is not due to the colonization efficiency of bacteria on the plant roots but could be due to a regulation of gene expression of carotenoid biosynthesis.
    Citation
    Alsharif, W. (2018). Molecular Characterization of the Plant Growth Promoting Bacterium Enterobacter sp. SA187 upon Contact with Arabidopsis thaliana. KAUST Research Repository. https://doi.org/10.25781/KAUST-296O3
    DOI
    10.25781/KAUST-296O3
    ae974a485f413a2113503eed53cd6c53
    10.25781/KAUST-296O3
    Scopus Count
    Collections
    Biological and Environmental Sciences and Engineering (BESE) Division; Bioscience Program; Theses; Theses

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