Homeodomain Leucine Zipper Class I Genes in Arabidopsis. Expression Patterns and Phylogenetic Relationships

• Published in: Plant physiology (Bethesda) 2005-09, Vol.139 (1), p.509-518
• Main Authors: Henriksson, Eva, Olsson, Anna S.B, Johannesson, Henrik, Johansson, Henrik, Hanson, Johannes, Engström, Peter, Söderman, Eva
• Format: Article
• Language: English
• Subjects: abscisic-acid; Amino Acid Sequence; amino acid sequences; Amino acids; Arabidopsis - drug effects; Arabidopsis - genetics; Arabidopsis - radiation effects; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - classification; Arabidopsis Proteins - genetics; Arabidopsis thaliana; Biological and medical sciences; cell-differentiation; DNA-binding; Fundamental and applied biological sciences. Psychology; gene duplication; Gene Expression Profiling; Gene expression regulation; Gene Expression Regulation, Plant - drug effects; Gene Expression Regulation, Plant - radiation effects; Genes; Genes. Genome; Genetics, Genomics, and Molecular Evolution; Genomes; genomics; HD-zip; homeobox gene; homeodomain proteins; Homeodomain Proteins - chemistry; Homeodomain Proteins - classification; Homeodomain Proteins - genetics; homeotic genes; layer-specific gene; leaf development; leucine zipper; Leucine Zippers - genetics; Light; light intensity; MHC class I genes; Molecular and cellular biology; Molecular genetics; molecular sequence data; nucleotide sequences; Phylogenetics; Phylogeny; Plant growth regulators; plant proteins; Plants; protein; RNA; Seedlings; sequence analysis; Sequence Homology, Amino Acid; transcription factors; Transcription Factors - chemistry; Transcription Factors - genetics; transcriptional activation; Water - pharmacology; water-deficit
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.105.063461

Members of the homeodomain leucine zipper (HDZip) family of transcription factors are present in a wide range of plants, from mosses to higher plants, but not in other eukaryotes. The HDZip genes act in developmental processes, including vascular tissue and trichome development, and several of them have been suggested to be involved in the mediation of external signals to regulate plant growth. The Arabidopsis (Arabidopsis thaliana) genome contains 47 HDZip genes, which, based on sequence criteria, have been grouped into four different classes: HDZip I to IV. In this article, we present an overview of the class I HDZip genes in Arabidopsis. We describe their expression patterns, transcriptional regulation properties, duplication history, and phylogeny. The phylogeny of HDZip class I genes is supported by data on the duplication history of the genes, as well as the intron/exon patterning of the HDZip-encoding motifs. The HDZip class I genes were found to be widely expressed and partly to have overlapping expression patterns at the organ level. Further, abscisic acid or water deficit treatments and different light conditions affected the transcript levels of a majority of the HDZip I genes. Within the gene family, our data show examples of closely related HDZip genes with similarities in the function of the gene product, but a divergence in expression pattern. In addition, six HDZip class I proteins tested were found to be activators of gene expression. In conclusion, several HDZip I genes appear to regulate similar cellular processes, although in different organs or tissues and in response to different environmental signals.