Targets of AtWRKY6 regulation during plant senescence and pathogen defense

  1. Silke Robatzek1 and
  2. Imre E. Somssich2
  1. Max-Planck-Institut für Züchtungsforschung, Abteilung Biochemie, 50829 Köln, Germany

Abstract

In Arabidopsis, WRKY factors comprise a large gene family of plant-specific transcriptional regulators controlling several types of plant stress responses. To understand the regulatory role of WRKY proteins during such processes, we identified targets of the senescence- and defense-associated WRKY6 factor. WRKY6 was found to suppress its own promoter activity as well as that of a closely related WRKY family member, indicating negative autoregulation. On the other hand, WRKY6 positively influenced the senescence- and pathogen defense-associated PR1 promoter activity, most likely involving NPR1 function. One novel identified target gene, SIRK, encodes a receptor-like protein kinase, whose developmental expression is strongly induced specifically during leaf senescence. The transcriptional activation of SIRK is dependent on WRKY6 function. Senescing leaves of wrky6 knockout mutants showed a drastic reduction, and green leaves of WRKY6 overexpression lines showed clearly elevated SIRK transcript levels. Furthermore, the SIRK gene promoter was specifically activated by WRKY6 in vivo, functioning very likely through direct W-box interactions.

Keywords

Footnotes

  • 1 Present address: Friedrich Miescher Institut, Maulbeerstrasse 66, 4058 Basel, Switzerland.

  • 2 Corresponding author.

  • E-MAIL somssich{at}mpiz-koeln.mpg.de; FAX 49-221-5062313.

  • Article and publication are at http://www.genesdev.org/cgi/doi/10.1101/gad.222702.

    • Received December 13, 2001.
    • Accepted March 5, 2002.
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