THE MAIZE CAFFEIC ACID O-METHYLTRANSFERASE GENE PROMOTER IS ACTIVE INTRANSGENIC TOBACCO AND MAIZE PLANT-TISSUES

The pattern of expression directed by the promoter of the maize caffei c acid O-methyltransferase (COMT) gene was studied by histochemical an d fluorometric beta-glucuronidase (GUS) analysis in transgenic maize a nd tobacco plants. The COMT promoter directs GUS expression to the xyl em and the other tissues undergoing lignification, and it responds to wounding and to elicitors. In transgenic maize plants, expression of G US corresponds to the pattern of expression of the endogenous COMT gen e as determined by northern analysis and in situ hybridization. The pa ttern in transgenic tobacco plants clearly shows that the maize promot er sequence is recognized by tobacco transcriptional factors, in spite of the anatomical differences and the evolutionary distance between t hese two species. The results suggest that the most significant promot er signals that induce the specific expression of the lignin COMT are conserved in different species.