title: Phytochrome A and phytochrome B mediate the hypocotyl-specific downregulation of TUB1 by light in arabidopsis.
abstract: Arabidopsis contains six alpha-tubulin and nine beta-tubulin genes that are expressed in a tissue-specific and developmentally regulated manner. We analyzed the effects of light on tubulin mRNA abundance in Arabidopsis seedlings using RNA gel blot hybridizations and gene-specific probes. Transcript levels of all 15 tubulin genes were decreased by continuous white light, although to different degrees. Detailed analysis was performed with the beta-tubulin TUB1 gene. The transcript level of TUB1 was high in etiolated seedlings and decreased to approximately 20% of the dark mRNA level after 2 to 6 hr of white light treatment. We showed that this downregulation requires high-irradiance light treatment and that multiple photoreceptors are involved. In particular, using phytochrome mutants and narrow wave band light, we demonstrated that both the phytochrome A (phyA)-mediated far-red light high-irradiance response and the phytochrome B (phyB)-mediated red light high-irradiance response are involved in the downregulation of TUB1 expression by white light. Histochemical analysis of transgenic plants expressing a TUB1-beta-glucuronidase chimeric transgene indicated that the downregulation observed only in hypocotyls and not in roots is controlled transcriptionally.
authors.affiliation: Laboratory of Plant Molecular Biology, Rockefeller University, New York, New York 10021-6399, USA.
authors.forename: W M
authors.initials: WM
authors.lastname: Leu
authors.forename: X L
authors.initials: XL
authors.lastname: Cao
authors.forename: T J
authors.initials: TJ
authors.lastname: Wilson
authors.forename: D P
authors.initials: DP
authors.lastname: Snustad
authors.forename: N H
authors.initials: NH
authors.lastname: Chua
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins; D001483:Base Sequence; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D005966:Glucuronidase / Q000096:biosynthesis; D008027:Light; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D009928:Organ Specificity; D010786:Photoreceptor Cells; D010834:Phytochrome / Q000378:metabolism*; D051942:Phytochrome A; D051939:Phytochrome B; D011401:Promoter Regions, Genetic; D018749:RNA, Plant / Q000302:isolation & purification / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000528:radiation effects; D014404:Tubulin / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D009838:Oligodeoxyribonucleotides; C497973:PHYA protein, Arabidopsis; C497952:PHYB protein, Arabidopsis; D051942:Phytochrome A; D018749:RNA, Plant; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D014404:Tubulin; D010834:Phytochrome; D051939:Phytochrome B; D005966:Glucuronidase