Mutant analyses define multiple roles for phytochrome C in Arabidopsis photomorphogenesis.
The analysis of Arabidopsis mutants deficient in the A, B, D, and E phytochromes has revealed that each of these phytochrome isoforms has both distinct and overlapping roles throughout plant photomorphogenesis. Although overexpression studies of phytochrome C (phyC) have suggested photomorphogenic roles for this receptor, conclusive evidence of function has been lacking as a result of the absence of mutants in the PHYC locus. Here, we describe the isolation of a T-DNA insertion mutant of phyC (phyC-1), the subsequent creation of mutant lines deficient in multiple phytochrome combinations, and the physiological characterization of these lines. In addition to operating as a weak red light sensor, phyC may perform a significant role in the modulation of other photoreceptors. phyA and phyC appear to act redundantly to modulate the phyB-mediated inhibition of hypocotyl elongation in red light and to function together to regulate rosette leaf morphology. In addition, phyC performs a significant role in the modulation of blue light sensing. Several of these phenotypes are supported by the parallel analysis of a quadruple mutant deficient in phytochromes A, B, D, and E, which thus contains only active phyC. Together, these data suggest that phyC has multiple functions throughout plant development that may include working as a coactivator with other phytochromes and the cryptochrome blue light receptors.
Franklin
Keara A
KA
Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom. kaf5@le.ac.uk
Davis
Seth J
SJ
Stoddart
Wendy M
WM
Vierstra
Richard D
RD
Whitelam
Garry C
GC
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000502:physiology; D018548:Cotyledon / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins / Q000235:genetics / Q000502:physiology; D018546:Hypocotyl / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D008027:Light; D009154:Mutation; D010641:Phenotype; D010786:Photoreceptor Cells; D017956:Photoreceptor Cells, Invertebrate; D010834:Phytochrome / Q000235:genetics* / Q000502:physiology; D051942:Phytochrome A; D051939:Phytochrome B; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects; D043562:Receptors, G-Protein-Coupled; D014157:Transcription Factors
D029681:Arabidopsis Proteins; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; C497973:PHYA protein, Arabidopsis; C497952:PHYB protein, Arabidopsis; D051942:Phytochrome A; D043562:Receptors, G-Protein-Coupled; D014157:Transcription Factors; C119828:cry protein, Drosophila; C406683:phytochrome C, Arabidopsis; D010834:Phytochrome; D051939:Phytochrome B