Light-dependent Translocation of a Phytochrome B-GFP Fusion Protein to the Nucleus in Transgenic Arabidopsis (original) (raw)
Related papers
Photocontrol of subcellular partitioning of phytochrome-B:GFP fusion protein in tobacco seedlings
The Plant Journal, 2000
Photomorphogenesis of higher plants is regulated by photoreceptors including the red/far-red lightabsorbing phytochromes, blue-UV/A sensing cryptochromes and as yet uncharacterized UV/B receptors. Speci®c 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¯uence 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 ampli®cation, a phenomenon that is thought to be mediated by interaction of phyB with CRY1.
The Plant Journal, 2000
Phytochromes (phy) are a family of photoreceptors that control various aspects of light-dependent plant development. Phytochrome A (phyA) is responsible for the very low¯uence response (VLFR) under inductive light conditions and for the high irradiance response (HIR) under continuous far-red light. We have recently shown that nuclear import of rice phyA:GFP is regulated by VLFR in transgenic tobacco. The import is preceded by very fast, light-induced formation of sequestered areas of phyA:GFP in the cytosol. Here we report that expression of the Arabidopsis phyA:GFP fusion protein in phyA-de®cient Arabidopsis plants complements the mutant phenotype. In these transgenic Arabidopsis lines, both light-dependent cytosolic formation of sequestered areas of the phyA:GFP as well as VLFR or HIRmediated nuclear import of the fusion protein was observed. By contrast, light-dependent nuclear import of the same fusion protein was induced only by continuous far-red light (HIR) but not by pulses of farred light (VLFR) in transgenic tobacco. These results demonstrate that photoregulation of intracellular partitioning of the Arabidopsis phyA:GFP differs signi®cantly in different genetic backgrounds.
The Plant Journal, 2003
The phytochrome (phy) family of sensory photoreceptors (phyA to phyE in Arabidopsis) enables plants to optimize their growth and development under natural light environments. Subcellular localization studies have shown that the photoreceptor molecule is induced to translocate from cytosol to nucleus by light, but direct evidence of the functional relevance of this translocation has been lacking. Here, using a glucocorticoid receptor-based fusion protein system, we demonstrate that both photoactivation and nuclear translocation combined are necessary and suf®cient for the biological function of phyB. Conversely, neither arti®cial nuclear translocation of non-photoactivated phyB nor arti®cial retention of photoactivated phyB in the cytosol provides detectable biological activity. Together these data indicate that signal transfer from photoactivated phyB to its primary signaling partner(s) is localized in the nucleus, and conversely suggest the absence of a cytosolic pathway from photoactivated phyB to light-responsive genes.
Annals of Botany, 1999
We present a characterization of transgenic Arabidopsis thaliana (L.) Heynh. plants expressing a chimeric gene comprising the Green Fluorescent Protein (GFP) and β-glucuronidase (GUS) coding sequences, fused to an efficient nuclear localization signal (NLS). The transgenic plants accumulate the fusion protein in their nuclei, and this provides a novel phenotype, that of green-fluorescent nuclei. The fluorescent nuclei are readily observed using conventional epifluorescence and laser scanning confocal microscopy. We describe the use of this phenotype for in i o studies of nuclear shape and movement, cell division, and for analysis of the transcriptional activities of constitutive and tissue-specific promoters. We propose that the phenotype of fluorescent nuclei will prove particularly valuable in histological, physiological and developmental studies of higher plants that require the facile observation of nuclei within living cells and in the absence of fixation or external staining.
Nucleo-cytoplasmic partitioning of the plant photoreceptors phytochromes
Seminars in Cell & Developmental Biology, 2000
Phytochromes in harmony with blue light photoreceptors play a major role in controlling plant growth and development from germination to seed maturation. Light absorption by phytochromes triggers a signaling cascade, phototransduction, which culminates in regulated gene expression. A major regulatory step at the cellular level, which affects specificities of light-induced physiological responses, seems to be the lightquality and light-quantity dependent nuclear import of the phytochromes themselves. The correlations found between the nuclear import of phytochromes (phyA and phyB) and various physiological responses regulated by these photoreceptors provides strong support for this hypothesis.
THE PLANT CELL ONLINE, 2008
It has been known for decades that red light pretreatment has complex effects on subsequent phototropic sensitivity of etiolated seedlings. Here, we demonstrate that brief pulses of red light given 2 h prior to phototropic induction by low fluence rates of blue light prevent the blue light-induced loss of green fluorescent protein-tagged phototropin 1 (PHOT1-GFP) from the plasma membrane of cortical cells of transgenic seedlings of Arabidopsis thaliana expressing PHOT1-GFP in a phot1-5 null mutant background. This red light effect is mediated by phytochrome A and requires ;2 h in the dark at room temperature to go to completion. It is fully far red reversible and shows escape from photoreversibility following 30 min of subsequent darkness. Red light-induced inhibition of blue light-inducible changes in the subcellular distribution of PHOT1-GFP is only observed in rapidly elongating regions of the hypocotyl. It is absent in hook tissues and in mature cells below the elongation zone. We hypothesize that red light-induced retention of the PHOT1-GFP on the plasma membrane may account for the red light-induced increase in phototropic sensitivity to low fluence rates of blue light.