Transcriptional regulation of the gluB promoter during plant response to infection.

Several studies suggest that plant hydrolytic enzymes, such as 1,3-beta-glucanases, may be components of a general defense system against pathogen invasion in several different plant species. We isolated and characterized a genomic sequence coding for a new acidic 1,3-beta-glucanase (gluB) from Solanum tuberosum. The 5' flanking region of the gluB gene was also characterized. A chimeric gene composed of 2998 bp of the promoter sequence from the gluB gene was fused to the beta-glucuronidase (GUS) coding region and used to transform potato and tobacco plants. Transcriptional activation of the gluB promoter was investigated in response to inoculation with Phytophthora infestans (Pi) or tobacco mosaic virus (TMV). In pathogen inoculated transgenic plants, GUS activity was strongly induced locally around necrotic lesions.