A LEAFY-like gene in the long-day plant, Silene coeli-rosa is dramatically up-regulated in evoked shoot apical meristems but does not complement the Arabidopsis lfy mutant

Abstract

A LEAFY-like gene was cloned in the long-day (LD) plant, Silene coeli-rosa (ScLFY). The open reading frame spans 1452 bp encoding a putative protein of 483 amino acids. Amino acid homology to other LFYs is 43-55%; conserved and variable regions were similar to others. However, an intron (808 bp) not found in others occurred close to the N-terminal of the C1 domain. Known features of transcription factors exhibited by ScLFY were an acidic domain in the central variable region, a proline-rich variable-region, and glutamate-rich regions. The proximal 5' untranslated region of ScLFY contains an 8 bp motif: CAACGGCC, which conforms to the Gibberellic Acid Regulatory Element (GARE), also found in the promoter of LFY in Arabidopsis. However, the 5' variable region of ScLFY is exceptionally long compared with other LFY genes. ScLFY failed to complement the Arabidopsis lfy mutant reflecting the substantial divergence of this gene. ScLFY was analysed during inductive and non-inductive treatments using RT-PCR. A clear up-regulation of ScLFY occurred in the apical meristem upon evocation of flowering, but it was barely detectable in non-inductive conditions. Thus, ScLFY is strongly up-regulated in evoked and young floral apices.