TRANSGENIC ANALYSIS OF A HYBRID POPLAR WOUND-INDUCIBLE PROMOTER REVEALS DEVELOPMENTAL PATTERNS OF EXPRESSION SIMILAR TO THAT OF STORAGE PROTEIN GENES

The wound-inducible win3 multigene family from hybrid poplars (Populus trichocarpa x Populus deltoides) encodes proteins with structural sim ilarities with Kunitz-type protease inhibitors (H.D. Bradshaw Jr., J.B . Hollick, T.J. Parsons, H.R.G. Clarke, M.P. Cordon [1990] Plant Mot B iol 14: 51-59), and at least one member, win3.12, is transcribed de no vo in the injured and uninjured leaves of wounded trees (J.B. Hollick, M.P. Cordon [1993] Plant Mol Biol 22: 561-572). A previous study demo nstrated that 1352 bp of 5' flanking DNA from the win3.12 gene confers local wound-regulated expression of the beta-glucuronidase gene in tr ansgenic tobacco (Nicotiana tabacum cv Xanthi n.c.) (J.B. Hollick, M.P . Cordon [1993] Plant Mol Biol 22: 561-572). We extend this transgenic analysis here by examining the developmental regulation and systemic wound induction conferred by the same transgene construct in tobacco. Biochemical and histochemical surveys of beta-glucuronidase activity a re described for four, independent transgenic lines. The observed spat ial and temporal expression patterns coincide with dormant storage tis sues and with previously described expression patterns for both seed a nd vegetative storage protein genes. Developmental northern blot analy sis of win3 RNA levels in poplar seeds confirms that proper temporal e xpression of the reporter gene is maintained during tobacco seed matur ation. These results demonstrate that a putative Kunitz-type protease inhibitor can be wound inducible in addition to being expressed in dev eloping seeds.