TOMATO PROSYSTEMIN PROMOTER CONFERS WOUND-INDUCIBLE, VASCULAR BUNDLE-SPECIFIC EXPRESSION OF THE BETA-GLUCURONIDASE GENE IN TRANSGENIC TOMATO PLANTS

Tomato (Lycopersicon esculentum Mill. cv. Better Boy) plants were tran sformed with a fused gene containing a 2.2-kb promoter fragment of the tomato prosystemin gene and the coding region of the beta-glucuronida se (GUS) reporter gene. The transgenic plants exhibited a low constitu tive level of prosystemin-beta-glucuronidase gene expression, assayed by histochemical staining and GUS enzyme activity, that was associated in the vascular bundles of leaf main veins, petiolules, petioles and stems. The GUS activity in the vascular bundles in each tissue was inc reased by wounding and by treatment of the plants with methyl jasmonat e, similar to the induction of prosystemin in wild-type plants. The in crease in GUS activity in the vascular bundles of leaves in response t o wounding correlated with the wound-inducible increase in prosystemin mRNA. Tissue printing, using rabbit anti-serum prepared against prosy stemin, confirmed that inducible prosystemin protein was localized in vascular bundles of petiolules, petioles and stems of wild-type tomato plants. The evidence indicates that the 2.2-kb promoter region of the tomato prosystemin gene contains elements conferring its correct temp oral and spatial expression in the vascular bundles of transgenic toma to plants.