The VERNALIZATION INDEPENDENCE 4 gene encodes a novel regulator of FLOWERING LOCUS C

• Published in: The Plant journal : for cell and molecular biology 2002-09, Vol.31 (5), p.663-673
• Main Authors: Zhang, Hua, Van Nocker, Steven
• Format: Article
• Language: English
• Subjects: Acclimatization - genetics; Acclimatization - physiology; Arabidopsis - genetics; Arabidopsis - physiology; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis Proteins - physiology; Biological and medical sciences; Biology and morphogenesis of the reproductive apparatus. Photoperiodism, vernalisation; Chromosomal Proteins, Non-Histone - genetics; Chromosomal Proteins, Non-Histone - metabolism; Chromosomal Proteins, Non-Histone - physiology; Cloning, Molecular; Cold Temperature; epigenetic; FLC; flowering; FRIGIDA; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; Genes, Regulator - genetics; MADS Domain Proteins - genetics; MADS Domain Proteins - physiology; Molecular Sequence Data; Mutation; Phenotype; Plant physiology and development; Plant Stems - genetics; Plant Stems - physiology; Plants, Genetically Modified; Transcription Factors - genetics; Transcription Factors - metabolism; Transcriptional Activation - genetics; Vegetative and sexual reproduction, floral biology, fructification; vernalization; VIP4
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313X.2002.01380.x

Summary The late‐flowering, vernalization‐responsive habit of many Arabidopsis ecotypes is mediated predominantly through repression of the floral programme by the FLOWERING LOCUS C (FLC) gene. To better understand this repressive mechanism, we have taken a genetic approach to identify novel genes that positively regulate FLC expression. We identified recessive mutations in a gene designated VERNALIZATION INDEPENDENCE 4 (VIP4), that confer early flowering and loss of FLC expression in the absence of cold. We cloned the VIP4 gene and found that it encodes a highly hydrophilic protein with similarity to proteins from yeasts, Drosophila, and Caenorhabditis elegans. Consistent with a proposed role as a direct activator of FLC, VIP4 is expressed throughout the plant in a pattern similar to that of FLC. However, unlike FLC, VIP4 RNA expression is not down‐regulated in vernalized plants, suggesting that VIP4 is probably not sufficient to activate FLC, and that VIP4 is probably not directly involved in a vernalization mechanism. Epistasis analysis suggests that VIP4 could act in a separate pathway from previously identified FLC regulators, including FRIGIDA and the autonomous flowering promotion pathway gene LUMINIDEPENDENS. Mutants lacking detectable VIP4 expression flower earlier than FLC null mutants, suggesting that VIP4 regulates flowering‐time genes in addition to FLC. Floral morphology is also disrupted in vip4 mutants; thus, VIP4 has multiple roles in development.