The regulation of the SARK promoter activity by hormones and environmental signals.
The Senescence Associated Receptor Protein Kinase (P(SARK)) promoter, fused to isopentenyltransferase (IPT) gene has been shown to promote drought tolerance in crops. We dissected P(SARK) in order to understand the various elements associated with its activation and suppression. The activity of P(SARK) was higher in mature and early senescing leaves, and abiotic stress induced its activity in mature leaves. Bioinformatics analysis suggests the interactions of multiple cis-acting elements in the control of P(SARK) activity. In vitro gel shift assays and yeast one hybrid system revealed interactions of P(SARK) with transcription factors related to abscisic acid and cytokinin response. Deletion analysis of P(SARK), fused to GUS-reporter gene was used to identify specific regions regulating transcription under senescence or during drought stress. Effects of exogenous hormonal treatments were characterized in entire plants and in leaf disk assays, and regions responsive to various hormones were defined. Our results indicate a complex interaction of plant hormones and additional factors modulating P(SARK) activity under stress resulting in a transient induction of expression.
Department of Plant Sciences, University of California, Davis, CA 95616, USA; Department of Crop Science, Agronomy School, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, 91501970, Brazil. Electronic address: cadtorre@ufrgs.br.
Carla A
CA
Delatorre
Department of Plant Sciences, University of California, Davis, CA 95616, USA; Department of Fruit Tree Sciences, Institute of Plant Sciences, Volcani Research Center (ARO), Bet Dagan, 50250, Israel. Electronic address: vhyuvalc@volcani.agri.gov.il.
Yuval
Y
Cohen
Department of Plant Sciences, University of California, Davis, CA 95616, USA.
Li
L
Liu
Department of Plant Sciences, University of California, Davis, CA 95616, USA.
Zvi
Z
Peleg
Department of Plant Sciences, University of California, Davis, CA 95616, USA. Electronic address: eblumwald@ucdavis.edu.
Eduardo
E
Blumwald
D000222:Adaptation, Physiological / Q000235:genetics; D000375:Aging / Q000235:genetics*; D001483:Base Sequence; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D059647:Gene-Environment Interaction; D017930:Genes, Reporter / Q000502:physiology; D008969:Molecular Sequence Data; D010937:Plant Growth Regulators / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics* / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000502:physiology; D011494:Protein Kinases / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
D010937:Plant Growth Regulators; D014157:Transcription Factors; D011494:Protein Kinases