Liège, Belgium
Liège, Belgium

Time filter

Source Type

Sadanandom A.,Durham University | Adam E.,Plant Biology Institute | Orosa B.,Durham University | Viczian A.,Plant Biology Institute | And 6 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

The red/far red light absorbing photoreceptor phytochrome-B (phyB) cycles between the biologically inactive (Pr, λmax, 660 nm) and active (Pfr; λmax, 730 nm) forms and functions as a light quality and quantity controlled switch to regulate photomorphogenesis in Arabidopsis. At the molecular level, phyB interacts in a conformation-dependent fashion with a battery of downstream regulatory proteins, including PHYTOCHROME INTERACTING FACTOR transcription factors, and by modulating their activity/abundance, it alters expression patterns of genes underlying photomorphogenesis. Here we report that the small ubiquitin-like modifier (SUMO) is conjugated (SUMOylation) to the C terminus of phyB; the accumulation of SUMOylated phyB is enhanced by red light and displays a diurnal pattern in plants grown under light/dark cycles. Our data demonstrate that (i) transgenic plants expressing the mutant phyBLys996Arg-YFP photoreceptor are hypersensitive to red light, (ii) light-induced SUMOylation of the mutant phyB is drastically decreased compared with phyB-YFP, and (iii) SUMOylation of phyB inhibits binding of PHYTOCHROME INTERACTING FACTOR 5 to phyB Pfr. In addition, we show that OVERLY TOLERANT TO SALT 1 (OTS1) de-SUMOylates phyB in vitro, it interacts with phyB in vivo, and the ots1/ots2 mutant is hyposensitive to red light. Taken together, we conclude that SUMOylation of phyB negatively regulates light signaling and it is mediated, at least partly, by the action of OTS SUMO proteases. © 2015, National Academy of Sciences. All rights reserved.


PubMed | Plant Biology Institute, Durham University, University of Edinburgh and Albert Ludwigs University of Freiburg
Type: Journal Article | Journal: Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

The red/far red light absorbing photoreceptor phytochrome-B (phyB) cycles between the biologically inactive (Pr, max, 660 nm) and active (Pfr; max, 730 nm) forms and functions as a light quality and quantity controlled switch to regulate photomorphogenesis in Arabidopsis. At the molecular level, phyB interacts in a conformation-dependent fashion with a battery of downstream regulatory proteins, including PHYTOCHROME INTERACTING FACTOR transcription factors, and by modulating their activity/abundance, it alters expression patterns of genes underlying photomorphogenesis. Here we report that the small ubiquitin-like modifier (SUMO) is conjugated (SUMOylation) to the C terminus of phyB; the accumulation of SUMOylated phyB is enhanced by red light and displays a diurnal pattern in plants grown under light/dark cycles. Our data demonstrate that (i) transgenic plants expressing the mutant phyB(Lys996Arg)-YFP photoreceptor are hypersensitive to red light, (ii) light-induced SUMOylation of the mutant phyB is drastically decreased compared with phyB-YFP, and (iii) SUMOylation of phyB inhibits binding of PHYTOCHROME INTERACTING FACTOR 5 to phyB Pfr. In addition, we show that OVERLY TOLERANT TO SALT 1 (OTS1) de-SUMOylates phyB in vitro, it interacts with phyB in vivo, and the ots1/ots2 mutant is hyposensitive to red light. Taken together, we conclude that SUMOylation of phyB negatively regulates light signaling and it is mediated, at least partly, by the action of OTS SUMO proteases.


Kircher S.,Albert Ludwigs University of Freiburg | Terecskei K.,Plant Biology Institute | Wolf I.,Albert Ludwigs University of Freiburg | Sipos M.,Plant Biology Institute | Adam E.,Plant Biology Institute
Plant Signaling and Behavior | Year: 2011

Among the five phytochromes in Arabidopsis thaliana, phytochrome A (phyA) plays a major role in seedling de-etiolation. Until now, more than 10 positive and some negative components acting downstream of phyA have been identified. However, their site of action and hierarchical relationships are not completely understood yet. © 2011 Landes Bioscience.


Wolf I.,Albert Ludwigs University of Freiburg | Kircher S.,Albert Ludwigs University of Freiburg | Fejes E.,Plant Biology Institute | Kozma-Bognar L.,Plant Biology Institute | And 4 more authors.
Plant and Cell Physiology | Year: 2011

The photoreceptor phytochrome-A (phyA) regulates germination and seedling establishment by mediating very low fluence (VLFR) and far-red high irradiance (FR-HIR) responses in Arabidopsis thaliana. In darkness, phyA homodimers exist in the biologically inactive Pr form and are localized in the cytoplasm. Light induces formation of the biologically active Pfr form and subsequent rapid nuclear import. PhyA Pfr, in contrast to the Pr form, is labile and has a half-life of ∼30 min. We produced transgenic plants in a phyA-201 null background that express the PHYA-yellow fluorescent protein (YFP) or the PHYA686-YFP-dimerization domain (DD) and PHYA686-YFP-DD-nuclear localization signal (NLS) or PHYA686-YFP-DD-nuclear exclusion signal (NES) fusion proteins. The PHYA686-YFP fusion proteins contained the N-terminal domain of phyA (686 amino acid residues), a short DD and the YFP. Here we report that (i) PHYA686-YFP-DD fusion protein is imported into the nucleus in a light-dependent fashion; (ii) neither of the PHYA686 fusion proteins is functional in FR-HIR and nuclear VLFR; and (iii) the phyA-dependent, blue light-induced inhibition of hypocotyl growth is mediated by the PHYA686-YFP-DD-NES but not by the PHYA686-YFP-DD-NLS and PHYA686-YFP-DD fusion proteins. We demonstrate that (i) light induces degradation of all PHYA N-terminal-containing fusion proteins and (ii) these N-terminal domain-containing fusion proteins including the constitutively nuclear PHYA686-YFP-DD-NLS and predominantly cytoplasmic PHYA686-YFP-DD-NES degrade at comparable rates but markedly more slowly than PHYA-YFP, whereas (iii) light-induced degradation of the native phyA is faster compared with PHYA-YFP. © 2011 The Author.


Kevers C.,Plant Molecular Biology and Biotechnology Unit | Kevers C.,Plant Biology Institute | Pincemail J.,University of Liège | Tabart J.,Plant Molecular Biology and Biotechnology Unit | And 3 more authors.
Journal of Agricultural and Food Chemistry | Year: 2011

Apple and pear fruits are important sources of secondary plant metabolites and one of the major sources of dietary phenolics consumed all year round. The aim of this work was to identify the main variables influencing phenolic content and antioxidant capacity in apples. Higher phenolic and antioxidant contents were observed in some varieties (such as the Delbar Estival apple and Durondeau pear). Storage conditions were important. Our results also showed that fruits should be consumed rapidly after purchase and with their peel. After one week of domestic storage, the ascorbic acid content was found to decrease by 75%. Peeling led to a more than 25% decrease in total phenolics and ascorbic acid. The harvest time (at normal ripeness) had only a limited impact, but significant year-to-year variations were observed. In conclusion, well-chosen and well-stored apples and pears may contribute to an antioxidant-rich diet if consumed rapidly and with their peel. © 2011 American Chemical Society.


Pincemail J.,University of Liège | Kevers C.,Plant Molecular Biology and Biotechnology Unit | Kevers C.,Plant Biology Institute | Tabart J.,Plant Molecular Biology and Biotechnology Unit | And 3 more authors.
Journal of Food Science | Year: 2012

Strawberries are a good source of micronutrients, especially antioxidant phenolics. More information is needed to better exploit the health-promoting effect of such fruits. Several studies focused on the effects of genotype, cultural practices, and seasonal variation on the antioxidant potential of strawberries, but often yielding contradictory results and/or focusing on only 1 source of variability. In the present study, we showed that total phenolic compounds, ascorbic acid, and antioxidant capacity strongly differed between genotypes of strawberry. The precise results revealed the importance of genetic background for the antioxidant capacity and for the content of total phenolics (with up to 3.3-fold variations). Other parameters may also influence the antioxidant capacity in strawberry such as harvest time, culture conditions, and environmental factors. Moreover, in this study, the harvesting time (at the same ripening stage) appeared to be very important, more important than genotype. Variations of the antioxidant capacity of up to 4.1-folds were observed following the harvesting time of "Elsanta" cultivar. © 2012 Institute of Food Technologists ®.


Josse E.-M.,University of Edinburgh | Gan Y.,University of York | Gan Y.,Zhejiang University | Bou-Torrent J.,Autonomous University of Barcelona | And 10 more authors.
Plant Cell | Year: 2011

The period following seedling emergence is a particularly vulnerable stage in the plant life cycle. In Arabidopsis thaliana, the phytochrome-interacting factor (PIF) subgroup of basic-helix-loop-helix transcription factors has a pivotal role in regulating growth during this early phase, integrating environmental and hormonal signals. We previously showed that SPATULA (SPT), a PIF homolog, regulates seed dormancy. In this article, we establish that unlike PIFs, which mainly promote hypo-cotyl elongation, SPT is a potent regulator of cotyledon expansion. Here, SPT acts in an analogous manner to the gibberellin-dependent DELLAs, REPRESSOR OF GA1-3 and GIBBERELLIC ACID INSENSITIVE, which restrain cotyledon expansion alongside SPT. However, although DELLAs are not required for SPT action, we demonstrate that SPT is subject to negative regulation by DELLAs. Cross-regulation of SPT by DELLAs ensures that SPT protein levels are limited when DELLAs are abundant but rise following DELLA depletion. This regulation provides a means to prevent excessive growth suppression that would result from the dual activity of SPT and DELLAs, yet maintain growth restraint under DELLA-depleted conditions. We present evidence that SPT and DELLAs regulate common gene targets and illustrate that the balance of SPT and DELLA action depends on light quality signals in the natural environment. © 2011 American Society of Plant Biologists.


Varallyay E.,Plant Biology Institute | Lichner Z.,Plant Biology Institute | Safrany J.,Plant Biology Institute | Havelda Z.,Plant Biology Institute | And 3 more authors.
Acta Biologica Hungarica | Year: 2010

Medicago truncatula, the model plant of legumes, is well characterized, but there is only a little knowledge about it as a viral host. Viral vectors can be used for expressing foreign genes or for virus-induced gene silencing (VIGS), what is a fast and powerful tool to determine gene functions in plants. Viral vectors effective on Nicotiana benthamiana have been constructed from a number of viruses, however, only few of them were effective in other plants. A Tobamovirus, Sunnhemp mosaic virus (SHMV) systemically infects Medicago truncatula without causing severe symptoms. To set up a viral vector for Medicago truncatula, we prepared an infectious cDNA clone of SHMV. We constructed two VIGS vectors differing in the promoter element to drive foreign gene expression. The vectors were effective both in the expression and in the silencing of a transgene Green Fluorescent Protein (GFP) and in silencing of an endogenous gene Phytoene desaturase (PDS) on N. benthamiana. Still only one of the vectors was able to successfully silence the endogenous Chlorata 42 gene in M. truncatula. © 2010 Akadémiai Kiadó, Budapest.


Csorba T.,Plant Biology Institute | Csorba T.,Eötvös Loránd University | Lozsa R.,Plant Biology Institute | Lozsa R.,Eötvös Loránd University | And 3 more authors.
Plant Journal | Year: 2010

RNA silencing plays an important role in plants in defence against viruses. To overcome this defence, plant viruses encode suppressors of RNA silencing. The most common mode of silencing suppression is sequestration of double-stranded RNAs involved in the antiviral silencing pathways. Viral suppressors can also overcome silencing responses through protein-protein interaction. The poleroviral P0 silencing suppressor protein targets ARGONAUTE (AGO) proteins for degradation. AGO proteins are the core component of the RNA-induced silencing complex (RISC). We found that P0 does not interfere with the slicer activity of pre-programmed siRNA/miRNA containing AGO1, but prevents de novo formation of siRNA/miRNA containing AGO1. We show that the AGO1 protein is part of a high-molecular-weight complex, suggesting the existence of a multi-protein RISC in plants. We propose that P0 prevents RISC assembly by interacting with one of its protein components, thus inhibiting formation of siRNA/miRNA-RISC, and ultimately leading to AGO1 degradation. Our findings also suggest that siRNAs enhance the stability of co-expressed AGO1 in both the presence and absence of P0. © 2010 The Authors. Journal compilation © 2010 Blackwell Publishing Ltd.


PubMed | Plant Biology Institute
Type: | Journal: Advances in virus research | Year: 2010

RNA silencing is an evolutionarily conserved sequence-specific gene-inactivation system that also functions as an antiviral mechanism in higher plants and insects. To overcome antiviral RNA silencing, viruses express silencing-suppressor proteins which can counteract the host silencing-based antiviral process. After the discovery of virus-encoded silencing suppressors, it was shown that these viral proteins can target one or more key points in the silencing machinery. Here we review recent progress in our understanding of the mechanism and function of antiviral RNA silencing in plants, and on the viruss counterattack by expression of silencing-suppressor proteins. We also discuss emerging evidence that RNA silencing and expression of viral silencing-suppressor proteins are tools forged as a consequence of virus-host coevolution for fine-tuning host-pathogen coexistence.

Loading Plant Biology Institute collaborators
Loading Plant Biology Institute collaborators