THE PROMOTER OF THE GENE ITR1 FROM BARLEY CONFERS A DIFFERENT TISSUE-SPECIFICITY IN TRANSGENIC TOBACCO

Tissue-specific expression of the gene coding for trypsin inhibitor BT I-CMe in barley (Itr1) occurs during the first half of endosperm devel opment. In transgenic tobacco, the Itr1 promoter drives expression of the beta-glucuronidase reporter gene not only in developing endosperm but also in embryo, cotyledons and the meristematic intercotyledonary zone of germinating seedlings. A promoter fragment extending 343 bp up stream of the translation initiation ATG codon was sufficient for full transgene expression, whereas, the proximal 83 bp segment of the prom oter was inactive. Possible reasons for the differences in expression patterns are discussed.