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Keywords:

  • diatom;
  • Ectocarpus;
  • expression analysis;
  • haptophyte;
  • heat shock transcription factor;
  • heterokont;
  • Myb transcription factor;
  • stramenopile;
  • stress;
  • transcription factor;
  • transposable elements;
  • zinc finger

Summary

  • By comparative analyses we identify lineage-specific diversity in transcription factors (TFs) from stramenopile (or heterokont) genome sequences. We compared a pennate (Phaeodactylum tricornutum) and a centric diatom (Thalassiosira pseudonana) with those of other stramenopiles (oomycetes, Pelagophyceae, and Phaeophyceae (Ectocarpus siliculosus)) as well as to that of Emiliania huxleyi, a haptophyte that is evolutionarily related to the stramenopiles.
  • We provide a detailed description of diatom TF complements and report numerous peculiarities: in both diatoms, the heat shock factor (HSF) family is overamplified and constitutes the most abundant class of TFs; Myb and C2H2-type zinc finger TFs are the two most abundant TF families encoded in all the other stramenopile genomes investigated; the presence of diatom and lineage-specific gene fusions, in particular a class of putative photoreceptors with light-sensitive Per-Arnt-Sim (PAS) and DNA-binding (basic-leucine zipper, bZIP) domains and an HSF-AP2 domain fusion.
  • Expression data analysis shows that many of the TFs studied are transcribed and may be involved in specific responses to environmental stimuli.
  • Evolutionary and functional relevance of these observations are discussed.