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    Diversity, ecology, and biotechnological potential of microorganisms naturally associated with plants in arid lands

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    Name:
    Maria Mosqueira Santillan Dissertation.pdf
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    26.25Mb
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    PDF
    Description:
    Maria Mosqueira Santillan Dissertation
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    Type
    Dissertation
    Authors
    Mosqueira Santillán, María José cc
    Advisors
    Daffonchio, Daniele cc
    Committee members
    Saikaly, Pascal cc
    Tester, Mark A. cc
    Cardinale, Massimiliano
    Program
    Bioscience
    KAUST Department
    Biological and Environmental Sciences and Engineering (BESE) Division
    Date
    2018-07
    Embargo End Date
    2019-07-17
    Permanent link to this record
    http://hdl.handle.net/10754/628046
    
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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 became available to the public after the expiration of the embargo on 2019-07-17.
    Abstract
    Plants naturally host complex microbial communities in which the plant and the symbiotic partners act as an integrated metaorganism. These communities include beneficial (i.e. plant growth promoting, PGP) microorganisms which provide fundamental ecological services able to enhance host plant fitness and stress tolerance. PGP microorganisms represent a potential bioresource for agricultural applications, especially for desert farming under the harsh environmental conditions occurring in hot/arid regions (i.e. drought and salinity). In this context, understanding the ecological aspects of the associated microorganisms is crucial to take advantage of their ecological services. Here, hot/desert ecosystems were selected and two contrasting plant categories were used as models: (i) wild plants (i.e. speargrasses) growing in hot-desert sand dunes and (ii) the main crop cultivated in desert ecosystems, the date palm. By using highthroughput DNA sequencing and microscopy, the ecology and functionality of the microbial communities associated with these plants were characterized. Additionally, the PGP services of bacteria isolated from date palm were explored. I found that the harsh conditions of the desert strongly affect the selection and assembly of microbial communities associated with three different speargrass species, determining a plant species-independent core microbiome always present among the three plant species and carrying important PGP traits. On the contrary, in agroecosystems where desert farming practices are used, the plant species, i.e. date palm exerts a stronger selective pressure than the environmental and edaphic factors favoring the recruitment of conserved microbial assemblages, independent of the differences in the soil and environmental conditions among the studied oases. Such selective pressure also favors the recruitment of conserved PGP microorganisms (i.e. Pseudomonas sp. bacterial strains) able to protect their host from salinity stress through the induction of root architectural changes regulated by the modification of the root system auxin homeostasis. Overall, we found that deserts are unique ecosystems that challenge the paradigm of microbial community assembly, as it was defined from studies in non-arid ecosystems. The understanding of the ecological features regulating the ecological properties of such unique microbial community assembly will be a key-step to improve the chances of successful application of ‘PGP microorganisms’ in arid agroecosystems.
    DOI
    10.25781/KAUST-FSR83
    ae974a485f413a2113503eed53cd6c53
    10.25781/KAUST-FSR83
    Scopus Count
    Collections
    Biological and Environmental Sciences and Engineering (BESE) Division; Bioscience Program; Dissertations

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