title: Promotion of transcript accumulation of novel Zinnia immature xylem-specific HD-Zip III homeobox genes by brassinosteroids.
abstract: We isolated three novel homeobox genes (ZeHB-10, -11 and -12) from Zinnia elegans to elucidate the molecular mechanism underlying vascular system formation. ZeHB-10, -11 and -12 encode for HD-Zip proteins of the class III to which Arabidopsis Athb-8, -9, -14, -15 and IFL1 belong. In situ hybridization analysis demonstrated that the ZeHB-10, -11 and -12 mRNAs accumulated preferentially in procambium and immature xylem cells in 14-day-old plants. Transcripts for the three genes also accumulated in cultured Zinnia cells in a xylogenesis-specific manner. The accumulation of transcripts for all of ZeHB-10, -11 and -12 in cultured Zinnia cells was suppressed strongly by uniconazole, an inhibitor of brassinosteroid synthesis, and such suppression was reversed by the addition of brassinolide, a biologically active brassinosteroid. Thus the expression of ZeHB-10, -11 and -12 may be regulated by endogenous levels of brassinosteroids. Taken together with the fact that ZeHB-10, -11 and -12 proteins can bind to each other in yeast, the roles of HD-Zip III genes in vascular development are discussed.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan. kyoko@biol.s.u-tokyo.ac.jp
authors.forename: Kyoko
authors.initials: K
authors.lastname: Ohashi-Ito
authors.forename: Taku
authors.initials: T
authors.lastname: Demura
authors.forename: Hiroo
authors.initials: H
authors.lastname: Fukuda
mesh_terms: D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D019659:Asteraceae / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D001692:Biological Transport; D060406:Brassinosteroids; D002777:Cholestanols / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D013260:Steroids, Heterocyclic / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D014230:Triazoles / Q000494:pharmacology
chemical_list: C098015:ATHB-8 protein, Arabidopsis; D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D002777:Cholestanols; D018076:DNA, Complementary; D018398:Homeodomain Proteins; C114644:PHV protein, Arabidopsis; D010940:Plant Proteins; D013260:Steroids, Heterocyclic; D014157:Transcription Factors; D014230:Triazoles; C092705:uniconazole; C023623:brassinolide