title: OsPIE1, the rice ortholog of Arabidopsis PHOTOPERIOD-INDEPENDENT EARLY FLOWERING1, is essential for embryo development.
abstract: BACKGROUND
  The SWR1 complex is important for the deposition of histone variant H2A.Z into chromatin necessary to robustly regulate gene expression during growth and development. In Arabidopsis thaliana, the catalytic subunit of the SWR1-like complex, encoded by PIE1 (PHOTOPERIOD-INDEPENDENT EARLY FLOWERING1), has been shown to function in multiple developmental processes including flowering time pathways and petal number regulation. However, the function of the PIE1 orthologs in monocots remains unknown.
  
  
  RESULTS
  We report the identification of the rice (Oryza sativa) ortholog, OsPIE1. Although OsPIE1 does not exhibit a conserved exon/intron structure as Arabidopsis PIE1, its encoded protein is highly similar to PIE1, sharing 53.9% amino acid sequence identity. OsPIE1 also has a very similar expression pattern as PIE1. Furthermore, transgenic expression of OsPIE1 completely rescued both early flowering and extra petal number phenotypes of the Arabidopsis pie1-2 mutant. However, homozygous T-DNA insertional mutants of OsPIE1 in rice were embryonically lethal, in contrast to the viable mutants in the orthologous genes for yeast, Drosophila and Arabidopsis (Swr1, DOMINO and PIE1, respectively).
  
  
  CONCLUSIONS
  Taken together, our results suggest that OsPIE1 is the rice ortholog of Arabidopsis PIE1 and plays an essential role in rice embryo development.
authors.affiliation: Province Key Laboratory of Genetic Engineering on Plant Metabolism, Virology and Biotechnology Institute, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
authors.forename: Yonghan
authors.initials: Y
authors.lastname: Xu
authors.forename: Minjuan
authors.initials: M
authors.lastname: Deng
authors.forename: Jianfei
authors.initials: J
authors.lastname: Peng
authors.forename: Zhanghua
authors.initials: Z
authors.lastname: Hu
authors.forename: Lieming
authors.initials: L
authors.lastname: Bao
authors.forename: Junming
authors.initials: J
authors.lastname: Wang
authors.forename: Zhi-Liang
authors.initials: ZL
authors.lastname: Zheng
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology; D020134:Catalytic Domain; D005091:Exons; D007438:Introns; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics / Q000502:physiology*; D030821:Plants, Genetically Modified; D012639:Seeds / Q000254:growth & development*; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000502:physiology*
chemical_list: C478983:PIE1 protein, Arabidopsis; D014157:Transcription Factors