title: The Tissue-Specific Expression of a Tobacco Phytochrome B Gene.
abstract: We have isolated a genomic clone from Nicotiana tabacum, designated Nt-PHYB-1, encoding a type-II, "green tissue" phytochrome apoprotein. Recombinant genes, consisting of the 3319-bp promoter of the Nt-PHYB-1 gene (including the entire 5[prime] untranslated sequence but not the ATG) or its deletion derivatives and the bacterial [beta]-glucuronidase reporter gene, were constructed and transferred into tobacco. The expression patterns and levels of the endogenous Nt-PHYB-1, as well as those of the transgenes, were determined by RNase protection assays and by [beta]-glucuronidase histochemical staining. We show that (a) the PHYB-1 gene has three transcription start sites, (b) the abundance of the three PHYB-1-specific mRNAs is different, and that (c) it is not regulated by light. However, we do demonstrate that transcription of the endogenous PHYB-1 gene and that of the recombinant genes exhibit a well-defined organ and tissue specificity. This tobacco PHYB gene is relatively highly expressed in leaf, stem, and different floral organs but not in root. Deletion analysis of the Nt-PHYB-1 promoter indicates that a 382-bp region, located between -1472 and -1089, is required for high-level expression of this gene.
authors.affiliation: The Biological Research Center of the Hungarian Academy of Sciences, Plant Biology Institute, H-6701 Szeged, P.O. Box 251, Hungary (E.A., L.K.-B., F.N.).
authors.forename: E.
authors.initials: E
authors.lastname: Adam
authors.forename: L.
authors.initials: L
authors.lastname: Kozma-Bognar
authors.forename: C.
authors.initials: C
authors.lastname: Kolar
authors.forename: E.
authors.initials: E
authors.lastname: Schafer
authors.forename: F.
authors.initials: F
authors.lastname: Nagy