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University of Queensland (2008)

Wheat Zinc Finger Proteins Potentially Involved in Drought Adaptation

Wing-hei Kam

Titre : Wheat Zinc Finger Proteins Potentially Involved in Drought Adaptation

Auteur : Wing-hei Kam

Grade : Doctor of Philosophy (PhD) 2008

Université de soutenance : University of Queensland

Résumé partiel
Water deficit is one of the major factors limiting wheat productivity in Australia. In response to water deficit, plants have developed various strategies to cope with stress conditions through a combination of metabolic, physiological and morphological changes. These drought adaptive changes rely largely on alterations in gene expression. Therefore, transcriptional regulators play an important role in drought adaptation. In this thesis regulatory genes from two zinc finger families (RING and Q-type C2H2 zinc finger) from Triticum aestivum (bread wheat) were investigated through extensive analyses of their expression profiles, sequence characterisation and DNA-binding specificity with a primary focus on identifying zinc finger genes involved in wheat drought adaptation. RING zinc finger proteins are known for their regulatory role in ubiquitin-mediated protein degradation and participate in interaction with other regulatory proteins. Seven RING zinc finger genes from T. aestivum (designated TaRZF) were analysed for expression profiles in various organs (leaf, root, stem, spike, endosperm and embryo), during leaf development and aging, as well as in wheat response to drought stress. Expression levels of six of these seven genes varied markedly among the six organs examined. All seven genes changed their expression levels in the leaf from the growing to senescing stage. Four genes were responsive to drought stress. A RINGH2 zinc finger gene, TaRZF70, showed differential response to water deprivation, namely upregulation in the leaf and down-regulation in the root. This differential response was also observed in abscisic acid (ABA)-treated plants. Sequence analysis revealed that TaRZF70 contains four RING-H2 domains. Bioinformatic analysis showed a transmembrane domain at the N-terminus of TaRZF70 and its RING domains sharing homology with previously characterised membraneassociated ubiquitin ligases. These results indicate that some of these RING zinc finger genes are involved in wheat response to drought and potentially participate in modulating the levels of some proteins involved in wheat drought adaptation through the ubiquitin-mediated protein degradation pathway.

Mots-clés : wheat, zinc finger, drought, developmental, DNA binding

Présentation

Page publiée le 24 mai 2011, mise à jour le 16 juillet 2017