TISSUE-SPECIFIC AND WOUND-INDUCIBLE PATTERN OF EXPRESSION OF THE MANNOPINE SYNTHASE PROMOTER IS DETERMINED BY THE INTERACTION BETWEEN POSITIVE AND NEGATIVE CIS-REGULATORY ELEMENTS

In transgenic tobacco plants the regulatory region of the Agrobacteriu m genes involved in mannopine synthesis (pmas) directs expression in v ascular tissues and is induced upon wounding. To identify cis-acting s equences required for the cell-type-specific and wound-inducible expre ssion of this regulatory region, the expression pattern of chimeric ge nes in which 5' upstream deletions of the pmas1' promoter direct the e xpression of the beta-glucuronidase coding sequence, was analyzed in t ransgenic tobacco plants. It was found that the pmas1' promoter is spe cifically expressed in phloem cells and that this tissue-specific patt ern of expression is the result of the interaction of at least two neg ative regulatory elements with a positive element that directs express ion in many cell types. It was also found that wound induction is medi ated by two different mechanisms, one of them involving a dramatic cha nge in tissue-specific expression.