title: Mutations in epidermis-specific HD-ZIP IV genes affect floral organ identity in Arabidopsis thaliana.
abstract: Development of the epidermis involves members of the class-IV homeodomain-leucine zipper (HD-ZIP IV) transcription factors. The Arabidopsis HD-ZIP IV family consists of 16 members, among which PROTODERMAL FACTOR 2 (PDF2) and ARABIDOPSIS THALIANA MERISTEM LAYER 1 (ATML1) play an indispensable role in the differentiation of shoot epidermal cells; however, the functions of other HD-ZIP IV genes that are also expressed specifically in the shoot epidermis remain to be fully elucidated. We constructed double mutant combinations of these HD-ZIP IV mutant alleles and found that the double mutants of pdf2-1 with homeodomain glabrous1-1 (hdg1-1), hdg2-3, hdg5-1 and hdg12-2 produced abnormal flowers with sepaloid petals and carpelloid stamens in association with the reduced expression of the petal and stamen identity gene APETALA 3 (AP3). Expression of another petal and stamen identity gene PISTILATA (PI) was less affected in these mutants. We confirmed that AP3 expression in pdf2-1 hdg2-3 was normally induced at the initial stages of flower development, but was attenuated both in the epidermis and internal cell layers of developing flowers. As the expression of PDF2 and these HD-ZIP IV genes during floral organ formation is exclusively limited to the epidermal cell layer, these double mutations may have non-cell-autonomous effects on AP3 expression in the internal cell layers. Our results suggest that cooperative functions of PDF2 and other members of the HD-ZIP IV family in the epidermis are crucial for normal development of floral organs in Arabidopsis.
authors.affiliation: Department of Biological Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Kamata
authors.forename: Hitomi
authors.initials: H
authors.lastname: Okada
authors.forename: Yoshibumi
authors.initials: Y
authors.lastname: Komeda
authors.forename: Taku
authors.initials: T
authors.lastname: Takahashi
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D035264:Flowers / Q000033:anatomy & histology / Q000235:genetics* / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D019441:Plant Epidermis / Q000235:genetics*; D030821:Plants, Genetically Modified
chemical_list: C101342:APETALA 3 protein, Arabidopsis; C103790:ATML1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D026161:MADS Domain Proteins; C472305:PDF2 protein, Arabidopsis; C090225:PISTILLATA protein, Arabidopsis
keywords: AP3; Arabidopsis thaliana; HD-ZIP IV; PDF2; epidermis; floral organ identity