title: Molecular phylogeny and expression of poplar circadian clock genes, LHY1 and LHY2.
abstract: LHY/CCA1 genes play a key role in the plant circadian clock system and are highly conserved among plant species. However, the evolutionary process of the LHY/CCA1 gene family remains unclear in angiosperms. To obtain details of the phylogeny of these genes, this study characterized LHY/CCA1 genes in a model woody plant,Populus tree.The evolutionary process of angiosperm LHY/CCA1 genes was elucidated using three approaches: comparison of exon–intron structures, reconstruction of phylogenetic trees and examination of syntenic relationships. In addition, the molecular evolutionary rates and the expression patterns of Populus LHYs were analyzed.Gene duplication events of Populus LHYs and Arabidopsis LHY/CCA1 had occurred independently by different chromosomal duplication events arising in each evolutionary lineage. Populus LHYs were under purifying selection by estimating substitution rates of these genes. Further, Populus LHYs conserved diurnal expressions in leaves and stems but the transcripts of LHY2 were more abundant than those of LHY1 in Populus plants.This study uncovered phylogenetic relationships of the LHY/CCA1 gene family in angiosperms. In addition, the transcript abundance and the evolutionary differences between Populus LHY1 and LHY2 imply that Populus LHY2, rather than LHY1, may have a major role in the Populus clock system.
authors.affiliation: United Graduate School of Agricultural Sciences, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Takata
authors.affiliation: Laboratory of Bioscience, Faculty of Engineering, Iwate University, Morioka 020-8551, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Saito
authors.affiliation: Laboratory of Bioscience, Faculty of Engineering, Iwate University, Morioka 020-8551, Japan.
authors.forename: Claire
authors.initials: C
authors.lastname: Tanaka Saito
authors.affiliation: Department of Molecular and Cell Biology, Forestry and Forest Products Research Institute, Tsukuba 305-8687, Japan.
authors.forename: Tokihiko
authors.initials: T
authors.lastname: Nanjo
authors.affiliation: Department of Molecular and Cell Biology, Forestry and Forest Products Research Institute, Tsukuba 305-8687, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Shinohara
authors.affiliation: United Graduate School of Agricultural Sciences, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan.|Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan.
authors.forename: Matsuo
authors.initials: M
authors.lastname: Uemura
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D002940:Circadian Rhythm; D019143:Evolution, Molecular; D020440:Gene Duplication; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D032107:Populus / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D016415:Sequence Alignment; D026801:Synteny
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger