title: Functional characterization of HY5 homolog genes involved in early light-signaling in Physcomitrella patens.
abstract: The developmental programs of Physcomitrella patens, a basal lineage of land plants, are regulated by phytohormones and light-signaling responses. In this study, our attention was focused on the HY5-family of transcription factors, which are known to play important roles immediately downstream of photoreceptors during the early photomorphogenesis of Arabidopsis thaliana. We retrieved two HY5-homologs, named PpHY5a and PpHY5b, from the whole genome sequence database of P. patens. Arabidopsis transgenic plants overproducing the basic leucine zipper (bZIP) domain of PpHY5a exhibited a phenotype of short hypocotyls, suggesting a functional relationship between PpHY5 and Arabidopsis HY5. A loss-of-function Δhy5a Δhy5b double mutant was defective in the vigorous protrusion of caulonema cells from the protonema networks of P. patens under light and dark conditions. These results suggest that the function of HY5-homologs in P. patens is evolutionarily conserved, and is implicated in a process of caulonema development.
authors.affiliation: School of Agriculture, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Japan.
authors.forename: Saori
authors.initials: S
authors.lastname: Yamawaki
authors.forename: Takafumi
authors.initials: T
authors.lastname: Yamashino
authors.forename: Hanayo
authors.initials: H
authors.lastname: Nakanishi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Mizuno
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D019068:Bryopsida / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D017124:Conserved Sequence; D017353:Gene Deletion; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D018546:Hypocotyl / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D008027:Light; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D016415:Sequence Alignment; D015398:Signal Transduction / Q000235:genetics*
chemical_list: D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; C109254:HY5 protein, Arabidopsis; D009687:Nuclear Proteins; D020033:Protein Isoforms