Universität zu Köln

Characterization of PDF1 and its interaction with DELAY OF GERMINATION1 (DOG1) in the control of seed dormancy in Arabidopsis thaliana

Miatton, Emma (2012) Characterization of PDF1 and its interaction with DELAY OF GERMINATION1 (DOG1) in the control of seed dormancy in Arabidopsis thaliana. PhD thesis, Universität zu Köln.

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    Abstract

    Seed dormancy is defined as the incapacity of a viable seed to germinate under favourable conditions. It is established during seed maturation and reaches high levels in mature dry seeds. Dormancy is a complex adaptive trait that assures germination at proper time of the year at the onset of the favourable growing season. This trait is regulated by hormonal and environmental cues such as temperature and light. In Arabidopsis thaliana dormancy can be released by imbibing seeds at cold temperatures (stratification) or by storing seeds in dry conditions (after- ripening). The molecular mechanisms that regulate the induction and the release of dormancy are still poorly understood. Previous studies identified DELAY OF GERMINATION1 (DOG1) as a key regulator of seed dormancy in Arabidopsis. The dog1 mutant completely lacks seed dormancy and has no pleiotropic effects. DOG1 shows a seed-specific expression pattern and the abundance of its protein correlates with the dormancy level in freshly harvested seeds. However, this correlation is lacking in after-ripened seeds, suggesting that the protein activity is lost during after ripening (Nakabayashi et al., 2012). DOG1 encodes a protein with unknown function and unknown regulation. The phosphatase PDF1 was identified as an interactor of DOG1 in a yeast two hybrid assay. This thesis describes the relation between PDF1 and DOG1 which was investigated in order to gain further insights into the regulation of DOG1 and into the mechanisms controlling seed dormancy. A T-DNA insertion mutant named pdf1-1 showed increased dormancy. PDF1 and DOG1 were co-expressed during seed maturation, interacted in vivo and were shown to function in the same pathway independent from ABA. Two-dimensional gels analysis showed that DOG1 is targeted by two different post-translational modifications during after ripening and after imbibition. DOG1 shifted towards a lower pH during after-ripening, while imbibition caused a shift towards the basic side. In the pdf1-1 mutant DOG1 was detected at a lower pH in comparison to Columbia, indicating possible increased phosphorylation levels and implying a role of PDF1 in the dephosphorylation of DOG1. Moreover, the shift of DOG1 caused by the after-ripening was not observed in the pdf1-1 mutant, suggesting that the post-translational modifications of DOG1 are interdependent.

    Item Type: Thesis (PhD thesis)
    Creators:
    CreatorsEmail
    Miatton, Emmaemma.miatton@gmail.com
    URN: urn:nbn:de:hbz:38-53242
    Subjects: Natural sciences and mathematics
    Life sciences
    Uncontrolled Keywords:
    KeywordsLanguage
    seed dormancy, Arabidopsis thalianaEnglish
    Faculty: Mathematisch-Naturwissenschaftliche Fakultät
    Divisions: Mathematisch-Naturwissenschaftliche Fakultät > MPI für Züchtungsforschung
    Language: English
    Date: November 2012
    Date Type: Publication
    Date of oral exam: 07 November 2012
    Full Text Status: Public
    Date Deposited: 10 Oct 2013 16:41:28
    Referee
    NameAcademic Title
    Koornneef, MaartenProf. Dr.
    URI: http://kups.ub.uni-koeln.de/id/eprint/5324

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