title: CRYPTOCHROME2 in vascular bundles regulates flowering in Arabidopsis.
abstract: Plants make full use of light signals to determine the timing of flowering. In Arabidopsis thaliana, a blue/UV-A photoreceptor, CRYPTOCHROME 2 (cry2), and a red/far-red photoreceptor, PHYTOCHROME B (phyB), are two major photoreceptors that control flowering. The light stimuli for the regulation of flowering are perceived by leaves. We have recently shown that phyB expression in mesophyll but not in vascular bundles suppresses the expression of a key flowering regulator, FLOWERING LOCUS T (FT), in vascular bundles. In this study, we asked where in the leaf cry2 perceives light stimuli to regulate flowering. To answer this question, we established transgenic Arabidopsis lines in which the cry2-green fluorescent protein (GFP) fusion was expressed under the control of organ/tissue-specific promoters in a cry2-deficient mutant background. Analysis of these lines revealed that expression of cry2-GFP in vascular bundles, but not in epidermis or mesophyll, rescued the late flowering phenotype. We further confirmed that cry2-GFP expressed in vascular bundles increased FT expression only in vascular bundles. Hence, in striking contrast with phyB, cry2 most likely regulates FT expression in a cell-autonomous manner.
authors.affiliation: Laboratory of Plant Physiology, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-Cho, Sakyo-Ku, Kyoto 606-8502, Japan.
authors.forename: Motomu
authors.initials: M
authors.lastname: Endo
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Mochizuki
authors.forename: Tomomi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Akira
authors.initials: A
authors.lastname: Nagatani
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D056931:Cryptochromes; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000032:analysis; D008027:Light; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000254:growth & development / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis
chemical_list: D029681:Arabidopsis Proteins; C103618:CRY2 protein, Arabidopsis; D056931:Cryptochromes; C418905:FT protein, Arabidopsis; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins