Abstract
WIPK (wound induced protein kinase) is a tobacco MAP kinase, transcripts of which are induced by mechanical wounding and TMV infection. In order to clarify the mechanisms of regulation of
WIPK expression, we isolated a 1122 bp section of the promoter region of the
WIPK gene and fused it to the
GUS reporter gene. Histochemical staining using a transgenic line containing this construct clearly showed WIPK to be almost exclusively localized at or near the sites of wounding and necrotic lesions. To identify the responsive elements, 5′-deletion constructs containing 874, 559 and 430 bp of the promoter regions, respectively, were fused to
GUS and transgenic tobacco lines containing these constructs were assayed for GUS induction upon wounding or on stimulation of a hypersensitive response (HR) after TMV infection. Measurement of enzymatic activity and Northern blot hybridization showed that the shortest promoter of 430 bp was sufficient for HR and a wound response, but that the extended region conferred a higher magnitude of response. It was thus suggested that, although the promoter region within 430 bp is essential,
WIPK is regulated by multiple factors including enhancer-like elements residing beyond the core region.