TEMPORAL AND SPATIAL PATTERN OF EXPRESSION OF THE PEA PHENYLALANINE AMMONIA-LYASE GENE1 PROMOTER IN TRANSGENIC TOBACCO

Genes encoding phenylalanine ammonia-lyase (PAL) form a small multigen e family with at least three members in pea. Tissue-specific expressio n of the promoter of a member of PAL gene family (PSPAL1) was investig ated in the transgenic tobacco transformants carrying the different mo des of chimeric fusion between the PSPAL1 promoter and a bacterial bet a-glucuronidase (GUS) gene. In stems, at least, strict correlation was found between steady-state levels of Gus-mRNA and enzyme activity. Si gnificantly high level of GUS activity was observed in roots, particul arly in meristematic tissues and the pigmented region of petals of tra nsgenic tobacco carrying the translational fusion type B (-1,394 to +1 40 of PSPAL1 connected to Gus), followed by moderately high level of G US activity carrying the translational fusion type A(-1,394 to +117). GUS expression in tissues of mature leaves, however, was very low in t hese constructs. Extremely low GUS activity was observed in the transf ormants of transcriptional fusion type (-1,394 to +5), whilst no activ ity was detected carrying non-transcription fusion type (-1,394 to -27 ). Furthermore, the pattern of the PSPAL1 expression was characterized in response to pathogen ingress and woundings in transgenic tobacco c arrying the translational fusion type B. Woundings itself triggered ma rked expression of PSPAL1-driven GUS expression at the wounded sites. Inoculation of nonpathogens, Phytophthora capsici, P. boehmeriae and E risiphe graminis f. sp. hordei, both caused rapid and very clear GUS e xpression zone along with the development of hypersensitive cell death area where callose was accumulated, however, the inoculation of a pat hogen, P. nicotiana caused slow and hazy GUS expression zone along wit h the lesion development. These results suggest that the expression of pea PSPAL1 promoter is regulated in a similar fashion, at least in a part, in pea and transgenic tobacco, under the plant development and v arious environmental cues.