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    Characterization of Strigolactone Antagonists as Inhibitor of Striga hermonthica Seed Germination and the Discovery of a Nitric Oxide Responsive Protein in Arabidopsis thaliana

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    PhD Dissertation-Final_Randa Zarban.pdf
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    Description:
    PhD Dissertation
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    Type
    Dissertation
    Authors
    Zarban, Randa Alhassan Yahya cc
    Advisors
    Al-Babili, Salim cc
    Committee members
    Arold, Stefan T. cc
    Blilou, Ikram cc
    Boyer, François-Didier
    Program
    Bioscience
    KAUST Department
    Biological and Environmental Science and Engineering (BESE) Division
    Date
    2021-11
    Embargo End Date
    2022-12-01
    Permanent link to this record
    http://hdl.handle.net/10754/673848
    
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    Access Restrictions
    At the time of archiving, the student author of this dissertation opted to temporarily restrict access to it. The full text of this dissertation will become available to the public after the expiration of the embargo on 2022-12-01.
    Abstract
    Plants have evolved different communication mechanisms that convey information encoded in chemical signals, both internally and to surrounding organisms. Two such signals are strigolactones (SLs) and nitric oxide (NO). SLs are plant hormones that shape plant architecture according to nutrition availability and mediate interactions with beneficial arbuscular mycorrhizal fungi. For this second purpose, plant roots release SLs into the soil where they also trigger seed germination in root parasitic weeds, such as Striga hermonthica. Attachment of Striga causes severe damage to crops yield, particularly in sub-Saharan Africa. One way to control this threat to food security in infested African regions is to develop SL antagonists, which can inhibit Striga germination. Recently, we have shown that Triton X-100 can bind to the Striga SL-receptor, HYPOSENSITIVE to LIGHT 7 (ShHTL7). In addition, triazole urea compounds have been shown to specifically bind to Oryza sativa SL-receptor DWARF-14 (OsD14), blocking SL signalling. Here we used the structures of Triton X-100 and triazole urea to design two isomers and putative ShHTL7 inhibitors: KK023-N1 and KK023-N2. We demonstrate that these compounds antagonize SL signalling in S. hermonthica via specific binding to ShHTL7, and that application of KK023-N1 results in a 38% reduction in Striga germination under greenhouse conditions. Furthermore, we discovered a histidine residue (H51) in ShHTL7, which may be involved in SL perception in addition to known residues. Substitution of H51 to asparagine (N) led to a significant reduction in ShHTL7 hydrolysis activity, indicating the importance of this H residue. Our work provides a starting point for designing new series of SLs inhibitors to combat Striga, and improve food security worldwide. NO is a gaseous signaling molecule involved in regulating plant development and adaptive responses to biotic and abiotic stresses. In this work, we characterized AtLRB3, a Light Response Bric-a-Brac/Tramtrack/Broad Complex (BTB) family protein, and showed that it contains a Heme Nitric Oxide/Oxygen (H-NOX) domain that can sense NO, providing an evidence of the existence of NO binding proteins in planta.
    Citation
    Zarban, R. A. Y. (2021). Characterization of Strigolactone Antagonists as Inhibitor of Striga hermonthica Seed Germination and the Discovery of a Nitric Oxide Responsive Protein in Arabidopsis thaliana. KAUST Research Repository. https://doi.org/10.25781/KAUST-3F91F
    DOI
    10.25781/KAUST-3F91F
    ae974a485f413a2113503eed53cd6c53
    10.25781/KAUST-3F91F
    Scopus Count
    Collections
    Biological and Environmental Science and Engineering (BESE) Division; Bioscience Program; PhD Dissertations

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