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    Potential of Bacterial Volatile Organic Compounds for Biocontrol of Fungal Phytopathogens and Plant Growth Promotion Under Abiotic Stress

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    Asma Soussi Dissertation.pdf
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    Description:
    Asma Soussi Dissertation
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    Type
    Dissertation
    Authors
    Soussi, Asma cc
    Advisors
    Daffonchio, Daniele cc
    Committee members
    Hong, Pei-Ying cc
    Al-Babili, Salim cc
    Tsiamis, George
    Program
    Environmental Science and Engineering
    KAUST Department
    Biological and Environmental Sciences and Engineering (BESE) Division
    Date
    2018-07
    Embargo End Date
    2019-07-29
    Permanent link to this record
    http://hdl.handle.net/10754/628055
    
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    Show full item record
    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 became available to the public after the expiration of the embargo on 2019-07-29.
    Abstract
    Bacterial volatile organic compounds (VOCs) are signal molecules that may have beneficial roles in the soil-plant-microbiome ecosystem. In this Ph.D. thesis, I aimed to assess and characterize the role of bacterial VOCs in plant tolerance to drought and in the biocontrol of fungal pathogens. I started by studying two root endophytic bacteria isolated from pepper plants cultivated under desert farming conditions. They showed an enhancement of pepper tolerance to drought stress and an amelioration of its physiological status. Moreover, they induced the expression of a vacuolar pyrophosphatase proton pump (V-PPase), implicated in the regulation of the vacuolar osmotic pressure, facilitating water uptake. Besides, the exposure of Arabidopsis thaliana plants, grown under salinity stress, to the volatile 2,3-butanediol, described for its plant growth promotion (PGP) potential, enhanced the plants tolerance to salinity, proving the potential involvement of this volatile in the osmotic stress resistance mechanism. Then, I studied VOCs released by three bacteria associated to healthy rice plants. Their released VOCs mixtures modified the color pattern of Magnaporthe oryzae, the agent of the rice blast disease, and protected rice from the pathogen infection. A significant reduction of melanin production, sporulation and appressoria formation was measured in presence of the bacterial VOCs, without major effects on mycelial proliferation. 1-butanol-3-methyl, one of the nine VOCs co-produced by the studied bacteria, proved its potential of reducing M. oryzae melanin in vitro. In vivo tests confirmed the infection inhibition effects mediated by the rice-bacterial VOCs, with a reduction of 94% of the disease incidence. Lastly, I compared the genomes of the five bacteria considered in the previous experimental studies. The PGP traits and the VOCs pathways identified from the genome analyses confirmed the effects observed with the in vitro and in vivo assays, revealing a complex mode of promotion and protection offered by the studied plant-associated bacteria. In conclusion, plant-associated bacterial VOCs can play potentially important roles in modulating plant drought tolerance and reducing fungal virulence. Such biological resources represent novel tools to counteract the deleterious effects of abiotic and biotic stresses and have the potential to be exploited for sustainable approaches in agriculture.
    DOI
    10.25781/KAUST-FEA32
    ae974a485f413a2113503eed53cd6c53
    10.25781/KAUST-FEA32
    Scopus Count
    Collections
    Biological and Environmental Sciences and Engineering (BESE) Division; Environmental Science and Engineering Program; Dissertations

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