title: Regulation of the activity of Korean radish cationic peroxidase promoter during dedifferentiation and differentiation.
abstract: Studies of the regulation of the activity of the Korean radish cationic peroxidase (KRCP) promoter during dedifferentiation and redifferentiation are reported here. Histochemical staining with 5-bromo-4-chloro-indolyl glucuronide (X-gluc) showed that only dedifferentiated marginal cells of leaf discs of the transgenic plants, but not of the interior region, were stained blue, as leaf discs were incubated on dedifferentiation-inducing medium from 5 days after callus induction (DACI). The levels of cationic peroxidase activity and of KRCP transcripts in Korean radish seedlings (Raphanus sativus L. F1 Handsome Fall) were also upregulated by a low ratio of cytokinin to auxin, but not by high concentrations of cytokinin. To identify important cis-regulatory regions controlling callus-specific expression, a series of 5' promoter deletions was carried out with KRCP::GUS gene fusion systems. The data suggest that at least two positively regulatory regions are involved in the KRCP::GUS expression during dedifferentiation induced by a low ratio of cytokinin to auxin: one from -471 to -242 and another from -241 to +196. GUS expression, however, was quickly decreased to a basal level during regeneration of root and shoot. Thus, the downstream region between +197 and +698 seems to be enough to suppress GUS expression of all constructs during regeneration. We further show that the 142-bp fragment (-471 to -328) has at least one cis-element to bind to the nuclear proteins from Korean radish seedlings induced by dedifferentiation.
authors.affiliation: Department of Biochemistry, College of Science, Yonsei University, Seoul 120-749, Korea.
authors.forename: Soung Soo
authors.initials: SS
authors.lastname: Kim
authors.forename: Suh-Yeon
authors.initials: SY
authors.lastname: Choi
authors.forename: Jin-Hyoun
authors.initials: JH
authors.lastname: Park
authors.forename: Dong Ju
authors.initials: DJ
authors.lastname: Lee
mesh_terms: D001483:Base Sequence; D003583:Cytokinins / Q000378:metabolism; D017931:DNA Primers; D005966:Glucuronidase / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D010544:Peroxidases / Q000235:genetics*; D018515:Plant Leaves / Q000201:enzymology* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D031224:Raphanus / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism
chemical_list: D003583:Cytokinins; D017931:DNA Primers; D007210:Indoleacetic Acids; D010544:Peroxidases; D005966:Glucuronidase