title: Interaction between the GROWTH-REGULATING FACTOR and KNOTTED1-LIKE HOMEOBOX families of transcription factors.
abstract: KNOTTED1-LIKE HOMEOBOX (KNOX) genes are important regulators of meristem function, and a complex network of transcription factors ensures tight control of their expression. Here, we show that members of the GROWTH-REGULATING FACTOR (GRF) family act as players in this network. A yeast (Saccharomyces cerevisiae) one-hybrid screen with the upstream sequence of the KNOX gene Oskn2 from rice (Oryza sativa) resulted in isolation of OsGRF3 and OsGRF10. Specific binding to a region in the untranslated leader sequence of Oskn2 was confirmed by yeast and in vitro binding assays. ProOskn2:β-glucuronidase reporter expression was down-regulated by OsGRF3 and OsGRF10 in vivo, suggesting that these proteins function as transcriptional repressors. Likewise, we found that the GRF protein BGRF1 from barley (Hordeum vulgare) could act as a repressor on an intron sequence in the KNOX gene Hooded/Barley Knotted3 (Bkn3) and that AtGRF4, AtGRF5, and AtGRF6 from Arabidopsis (Arabidopsis thaliana) could repress KNOTTED-LIKE FROM ARABIDOPSIS THALIANA2 (KNAT2) promoter activity. OsGRF overexpression phenotypes in rice were consistent with aberrant meristematic activity, showing reduced formation of tillers and internodes and extensive adventitious root/shoot formation on nodes. These effects were associated with down-regulation of endogenous Oskn2 expression by OsGRF3. Conversely, RNA interference silencing of OsGRF3, OsGRF4, and OsGRF5 resulted in dwarfism, delayed growth and inflorescence formation, and up-regulation of Oskn2. These data demonstrate conserved interactions between the GRF and KNOX families of transcription factors in both monocot and dicot plants.
authors.affiliation: Institute of Biology, Leiden University, Sylvius Laboratory, 2300 RA Leiden, The Netherlands.
authors.forename: Suzanne J H
authors.initials: SJ
authors.lastname: Kuijt
authors.forename: Raffaella
authors.initials: R
authors.lastname: Greco
authors.forename: Adamantia
authors.initials: A
authors.lastname: Agalou
authors.forename: Jingxia
authors.initials: J
authors.lastname: Shao
authors.forename: Corine C J
authors.initials: CC
authors.lastname: 't Hoen
authors.forename: Elin
authors.initials: E
authors.lastname: Overnäs
authors.forename: Michela
authors.initials: M
authors.lastname: Osnato
authors.forename: Serena
authors.initials: S
authors.lastname: Curiale
authors.forename: Donaldo
authors.initials: D
authors.lastname: Meynard
authors.forename: Robert
authors.initials: R
authors.lastname: van Gulik
authors.forename: Simone
authors.initials: S
authors.lastname: de Faria Maraschin
authors.forename: Mirna
authors.initials: M
authors.lastname: Atallah
authors.forename: Rolf J
authors.initials: RJ
authors.lastname: de Kam
authors.forename: Gerda E M
authors.initials: GE
authors.lastname: Lamers
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Guiderdoni
authors.forename: Laura
authors.initials: L
authors.lastname: Rossini
authors.forename: Annemarie H
authors.initials: AH
authors.lastname: Meijer
authors.forename: Pieter B F
authors.initials: PB
authors.lastname: Ouwerkerk
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D018744:DNA, Plant / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D005966:Glucuronidase / Q000378:metabolism; D001467:Hordeum / Q000378:metabolism*; D009928:Organ Specificity / Q000235:genetics; D012275:Oryza / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D010641:Phenotype; D018515:Plant Leaves / Q000378:metabolism / Q000648:ultrastructure; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D018517:Plant Roots / Q000254:growth & development; D018520:Plant Shoots / Q000254:growth & development; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D015854:Up-Regulation
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins; D014157:Transcription Factors; D005966:Glucuronidase