title: Homeodomain-Leucine Zipper II family of transcription factors to the limelight: central regulators of plant development.
abstract: The Arabidopsis genome encodes 10 Homeodomain-Leucine Zipper (HD-Zip) II transcription factors that can be subdivided into 4 clades (α-δ). All the γ (ARABIDOPSIS THALIANA HOMEOBOX 2 [ATHB2], HOMEOBOX ARABIDOPSIS THALIANA 1 [HAT1], HAT2) and δ (HAT3, ATHB4) genes are regulated by light quality changes (Low Red [R]/Far-Red [FR]) that induce the shade avoidance response in most of the angiosperms. HD-Zip IIγ and HD-Zip IIδ transcription factors function as positive regulators of shade avoidance, and there is evidence that at least ATHB2 is directly positively regulated by the basic Helix-Loop-Helix (bHLH) proteins PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and PIF5. Recent evidence demonstrate that, in addition to their function in shade avoidance, HD-Zip IIγ and HD-Zip IIδ proteins play an essential role in plant development from embryogenesis onwards in a white light environment.
authors.affiliation: Institute of Molecular Biology and Pathology; National Research Council; Rome, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Carabelli
authors.forename: Luana
authors.initials: L
authors.lastname: Turchi
authors.forename: Valentino
authors.initials: V
authors.lastname: Ruzza
authors.forename: Giorgio
authors.initials: G
authors.lastname: Morelli
authors.forename: Ida
authors.initials: I
authors.lastname: Ruberti
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D016350:Leucine Zippers; D008027:Light; D063245:Plant Development / Q000528:radiation effects; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D014157:Transcription Factors
keywords: Arabidopsis; HD-Zip III transcription factors; auxin; bHLH transcription factors; embryo patterning; organ polarity; shade avoidance