Details

Autor(en) / Beteiligte

• Su, Yi-shin
• Lagarias, J. Clark

Titel

Light-Independent Phytochrome Signaling Mediated by Dominant GAF Domain Tyrosine Mutants of Arabidopsis Phytochromes in Transgenic Plants

Ist Teil von

• The Plant cell, 2007-07, Vol.19 (7), p.2124-2139

Ort / Verlag

United States: American Society of Plant Biologists

Erscheinungsjahr

2007

Quelle

MEDLINE

Beschreibungen/Notizen

• The photoreversibility of plant phytochromes enables continuous surveillance of the ambient light environment. Through expression of profluorescent, photoinsensitive Tyr-to-His mutant alleles of Arabidopsis thaliana phytochrome B (PHYBY²⁷⁶H) and Arabidopsis phytochrome A (PHYAY²⁴²H) in transgenic Arabidopsis plants, we demonstrate that photoconversion is not a prerequisite for phytochrome signaling. PHYBY²⁷⁶H-expressing plants exhibit chromophore-dependent constitutive photomorphogenesis, light-independent phyBY²⁷⁶H nuclear localization, constitutive activation of genes normally repressed in darkness, and light-insensitive seed germination. Fluence rate analyses of transgenic plants expressing PHYBY²⁷⁶H, PHYAY²⁴²H, and other YGAF mutant alleles of PHYB demonstrate that a range of altered light-signaling activities are associated with mutation of this residue. We conclude that the universally conserved GAF domain Tyr residue, with which the bilin chromophore is intimately associated, performs a critical role in coupling light perception to signal transduction by plant phytochromes.