Photocontrol of subcellular partitioning of phytochrome-B:GFP fusion protein in tobacco seedlings.
Photomorphogenesis of higher plants is regulated by photoreceptors including the red/far-red light-absorbing phytochromes, blue-UV/A sensing cryptochromes and as yet uncharacterized UV/B receptors. Specific phototransduction pathways that are controlled by either individual or interacting photoreceptors mediate regulation. Phytochrome B (phyB) is the major red light-sensing photoreceptor. Phototransduction mediated by this light sensor has been shown to include light-dependent nuclear import and interaction of phyB with transcription factor-like proteins in the nucleus. Here we report that nuclear import of phyB and physiological responses regulated by this photoreceptor exhibit very similar wavelength- and fluence rate-dependence. Nuclear import of phyB is insensitive to single red, blue and far-red light pulses. It is induced by continuous red light and to a lesser extent by continuous blue light, whereas far-red light is completely ineffective. The data presented indicate that light-dependent partitioning of phyB exhibits features characteristic of blue light responsiveness amplification, a phenomenon that is thought to be mediated by interaction of phyB with CRY1.
Gil
P
P
Institut für Biologie II, Universität Freiburg, Schänzlestr. 1, D-79104 Freiburg, Hungary.
Kircher
S
S
Adam
E
E
Bury
E
E
Kozma-Bognar
L
L
Schäfer
E
E
Nagy
F
F
D002451:Cell Compartmentation; D002467:Cell Nucleus / Q000378:metabolism* / Q000502:physiology; D049452:Green Fluorescent Proteins; D008027:Light; D008164:Luminescent Proteins / Q000235:genetics; D008856:Microscopy, Fluorescence; D010786:Photoreceptor Cells; D010834:Phytochrome / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D051939:Phytochrome B; D010944:Plants; D030821:Plants, Genetically Modified / Q000378:metabolism / Q000502:physiology; D010947:Plants, Toxic; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D013347:Subcellular Fractions / Q000378:metabolism; D014026:Nicotiana / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors
D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D010834:Phytochrome; D051939:Phytochrome B; D049452:Green Fluorescent Proteins