Poster: Vegetative development

Abs # 325: Targets and function of WRKY53 during leaf senescence of Arabidopsis thaliana

Presenter:	Zentgraf, Ulrike , ulrike.zentgraf@uni-tuebingen.de
Authors	Zentgraf, Ulrike  (A)   Miao, Ying  (A)   Laun, Thomas  (A)
Affiliations:	(A): ZMBP-General Genetics

Arabidopsis WRKY proteins comprise a family of plant specific zinc-finger-type transcription factors involved in the regulation of gene expression during pathogen defense, wounding, trichome development, and senescence. To understand the regulatory role of the senescence related WRKY53 factor, we identified targets of this transcription factor by a pull down assay using genomic DNA and recombinant WRKY53 protein. We isolated a number of candidate target genes including other transcription factors, also of the WRKY family, stress- and defense related genes, and senescence-associated genes (SAGs). WRKY53 protein could bind to these different promoters in vitro and in vivo and it could act either as transcriptional activator or transcriptional repressor depending on the sequences surrounding the W-boxes. WRKY53 can be induced by hydrogen peroxide and can regulate its own expression in a negative feed back loop. Two kinases are involved in the upstream regulation of the WRKY53 expression. Our results suggest that WRKY53 acts in a complex transcription factor signalling network regulating senescence specific gene expression and hydrogen peroxide might be involved in signal transduction.