Sandy Vanderauwera's scientific contributionswhile working at Ghent University (Gent, Belgium) and other institutions

Publications (24)

1 2

Publications citing this author (6820)

    • For APX, it has been mentioned that its synthesis and activity would increase with high light reaching very high affinities at low concentrations of H 2 O 2 (at micromolar and submicromolar range) (Cakmak and Marschner 1992; Mittler and Poulos 2007). In contrast to CAT whose low affinity with H 2 O 2 would induce its activity only in a milieu characterized by high concentrations of H 2 O 2 (millimolar range) (Nicholls et al. 2001), offsetting in some degree the lower activity of APX during phases of decreasing light intensity (Pnueli et al. 2003; Vandenabeele et al. 2004 ). Thus, the balance between SOD and APX- CAT in synchrony with different mitigation mechanisms seems to be crucial to reach the steady state of superoxide radical and H 2 O 2 , minimizing cell damage in intertidal macroalgae (Mittler 2002; Suzuki et al. 2012).
    [Show abstract] [Hide abstract] ABSTRACT: Intertidal macroalgae are constantly subjected to high variations in the quality and quantity of incident irradiance that can eventually generate detrimental effect on the photosynthetic apparatus. The success of these organisms to colonize the stressful coastal habitat is mainly associated with the complexity of their morphological structures and the efficiency of the anti-stress mechanisms to minimize the physiological stress. Lessonia spicata (Phaeophyceae), a brown macroalga, that inhabits the intertidal zone in central-southern Chile was studied in regard their physiological (quantum yield, electron transport rate, pigments) and biochemical (phlorotannins content, antioxidant metabolism, oxidative stress) responses during a daily light cycle under natural solar radiation. Major findings were that Fv/Fm, photosynthetic parameters (ETRmax, alpha, Ek) and pigments in L. spicata showed an inverse relationship to the diurnal changes in solar radiation. Phlorotannins levels and antioxidant activity showed their highest values in treatment that included UV radiation. There was an increase in SOD and APX in relation at light stress, with a peak in activity between 5.2 and 10.1 Wm-2 of biologically effective dose. The increase in peroxidative damage was proportional to light dose. These results indicated that different light doses can trigger a series of complementary mechanisms of acclimation in L. spicata based on: i) down-regulation of photochemistry activity and decrease in concentration of photosynthetic pigments; ii) induction of phenolic compounds with specific UV-screening functions; iii) reactive oxygen species (ROS) scavenging activity via complementary repair of the oxidative damage through increased activity of antioxidant enzymes and potentially increased amounts of phenolic compounds.
    Full-text · Article · Feb 2017
    +1 more author...
    Read full-text
    • The GLTP gene in Arabidopsis has not been characterized. However, a related gene ACCELER- ATED CELL DEATH 11 (ACD11) regulates cell death through transport of ceramide-1-phos- phate and the acd11 mutant exhibits runaway cell death [56][57][58]. The acd11 mutant can be partially rescued by expression of a human GLTP [57], suggesting a cell death regulatory role also for Arabidopsis GLTP.
    [Show abstract] [Hide abstract] ABSTRACT: Plants are exposed to abiotic and biotic stress conditions throughout their lifespans that activates various defense programs. Programmed cell death (PCD) is an extreme defense strategy the plant uses to manage unfavorable environments as well as during developmentally induced senescence. Here we investigated the role of leaf age on the regulation of defense gene expression in Arabidopsis thaliana. Two lesion mimic mutants with misregulated cell death, catalase2 (cat2) and defense no death1 (dnd1) were used together with several double mutants to dissect signaling pathways regulating defense gene expression associated with cell death and leaf age. PCD marker genes showed leaf age dependent expression, with the highest expression in old leaves. The salicylic acid (SA) biosynthesis mutant salicylic acid induction deficient2 (sid2) had reduced expression of PCD marker genes in the cat2 sid2 double mutant demonstrating the importance of SA biosynthesis in regulation of defense gene expression. While the auxin- and jasmonic acid (JA)- insensitive auxin resistant1 (axr1) double mutant cat2 axr1 also led to decreased expression of PCD markers; the expression of several marker genes for SA signaling (ISOCHORISMATE SYNTHASE 1, PR1 and PR2) were additionally decreased in cat2 axr1 compared to cat2. The reduced expression of these SA markers genes in cat2 axr1 implicates AXR1 as a regulator of SA signaling in addition to its known role in auxin and JA signaling. Overall, the current study reinforces the important role of SA signaling in regulation of leaf age-related transcript signatures.
    Full-text · Article · Jan 2017
    Read full-text
    • Several studies have linked kinase receptors to oxidative stress and pathogen responses (Wrzaczek et al. 2013). In addition, recent work showed that many genes encoding kinase receptors are up-regulated in the null lsd1 (lesion simulating disease1) mutant (Wituszynska et al. 2013). LSD1 and CATALASE3 (CAT3) proteins interact and the lsd1 mutant displays reduced catalase activity and increased sensitivity to 3-AT, an inhibitor of CAT2 enzymatic activity that provokes H2O2 accumulation and subsequent plant death (Li et al. 2013).
    [Show abstract] [Hide abstract] ABSTRACT: Epigenetic regulatory states can persist through mitosis and meiosis, but the connection between chromatin structure and DNA replication remains unclear. Arabidopsis INCURVATA2 (ICU2) encodes the catalytic subunit of DNA polymerase α, and null alleles of ICU2 have an embryo-lethal phenotype. Analysis of icu2-1, a hypomorphic allele of ICU2, demonstrated that ICU2 functions in chromatin-mediated cellular memory; icu2-1 strongly impairs ICU2 function in the maintenance of repressive epigenetic marks but does not seem to affect ICU2 polymerase activity. To better understand the global function of ICU2 in epigenetic regulation, here we performed a microarray analysis of icu2-1 mutant plants. We found that the genes up-regulated in the icu2-1 mutant included genes encoding transcription factors and targets of the Polycomb Repressive Complexes. The down-regulated genes included many known players in salicylic acid (SA) biosynthesis and accumulation, ABA signaling and ABA-mediated responses. In addition, we found that icu2-1 plants had reduced SA levels in normal conditions; infection by Fusarium oxysporum induced SA accumulation in the En-2 wild type but not in the icu2-1 mutant. The icu2-1 plants were also hypersensitive to salt stress and exogenous ABA in seedling establishment, post-germination growth and stomatal closure, and accumulated more ABA than the wild type in response to salt stress. The icu2-1 mutant also showed high tolerance to the oxidative stress produced by 3-amino-1,2,4-triazole (3-AT). Our results uncover a role for ICU2 in the regulation of genes involved in ABA signaling as well as in SA biosynthesis and accumulation.
    Full-text · Article · Oct 2015
    +1 more author...
    Read full-text
    • The PsbS-overexpressing line oePsbS was kindly provided by Professor K. Niyogi and Professor Jansson (Li et al. 2002a, Johansson Jänkänpää et al. 2013). Arabidopsis thaliana plants were grown in standard laboratory conditions as described before (Wituszynska et al. 2013).
    [Show abstract] [Hide abstract] ABSTRACT: Natural capacity has evolved in higher plants to absorb and harness excessive light energy. In naive models the majority of absorbed photon energy is radiated back as fluorescence and heat. For years the photon sensor protein PsbS was considered to play a critical role in non-photochemical quenching (NPQ) of light absorbed by PSII antennas and in its dissipation as heat. However, the significance of PsbS in regulating heat emission from a whole leaf has never been verified before by direct measurement of foliar temperature under changing light intensity. To test its validity, we here investigated the foliar temperature changes on increasing and decreasing light intensity conditions (foliar temperature dynamics) using high resolution thermal camera and a powerful adjustable LED light source. Firstly, we showed that light dependent foliar temperature dynamics is correlated with chlorophyll content in leaves of various plant species. Secondly, we compared the foliar temperature dynamics in Arabidopsis thaliana wild-type, the PsbS null mutant npq4-1 and a PsbS overexpressing transgenic line under different transpiration conditions with or without a photosynthesis inhibitor. We found no direct correlations between the NPQ level and the foliar temperature dynamics. Rather, foliar temperature differences are primarily affected by stomatal aperture and rapid foliar temperature increase during irradiation depends on water status of the leaf. We conclude that PsbS is not directly involved in regulation of foliar temperature dynamics during excessive light energy episodes.
    Full-text · Article · Jun 2016
    +1 more author...
    Read full-text
    • We found that the majority of BrPIP genes were significantly down-regulated during drought stress treatment (Fig. 6b). Mittler et al. [46] reported that quick accumulation of reactive oxygen species (ROS) leads to damage of the cell membrane and oxidation of proteins, lipids, and DNA during drought stress. Down-regulation of BrPIP gene expression during drought stress may reduce membrane water permeability and cellular water conservation during dehydration periods.
    [Show abstract] [Hide abstract] ABSTRACT: Background Plants contain a range of aquaporin (AQP) proteins, which act as transporter of water and nutrient molecules through living membranes. AQPs also participate in water uptake through the roots and contribute to water homeostasis in leaves. Results In this study, we identified 59 AQP genes in the B. rapa database and Br135K microarray dataset. Phylogenetic analysis revealed four distinct subfamilies of AQP genes: plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), NOD26-like intrinsic proteins (NIPs) and small basic intrinsic proteins (SIPs). Microarray analysis showed that the majority of PIP subfamily genes had differential transcript abundance between two B. rapa inbred lines Chiifu and Kenshin that differ in their susceptibility to cold. In addition, all BrPIP genes showed organ-specific expression. Out of 22 genes, 12, 7 and 17 were up-regulated in response to cold, drought and salt stresses, respectively. In addition, 18 BrPIP genes were up-regulated under ABA treatment and 4 BrPIP genes were up-regulated upon F. oxysporum f. sp. conglutinans infection. Moreover, all BrPIP genes showed down-regulation under waterlogging stress, reflecting likely the inactivation of AQPs controlling symplastic water movement. Conclusions This study provides a comprehensive analysis of AQPs in B. rapa and details the expression of 22 members of the BrPIP subfamily. These results provide insight into stress-related biological functions of each PIP gene of the AQP family, which will promote B. rapa breeding programs. Electronic supplementary material The online version of this article (doi:10.1186/s12870-017-0979-5) contains supplementary material, which is available to authorized users.
    Full-text · Article · Dec 2017
    +1 more author...
    Read full-text
    • Anthocyanins, synthesized through the flavonoid pathway, are important secondary metabolites for plants flower pigmentation, seed dispersal, fruits coloration and resistance against biotic or abiotic stresses[1][2][3][4]. Due to high antioxidant activity, anthocyanins are critical antioxidants to protect plants against accumulation of reactive oxygen species (ROS), as observed in rats and humans[5,6]. Bright organ colors derived from anthocyanin accumulation directly determine ornamental, diet and market values of fruits and ornamental crops.
    [Show abstract] [Hide abstract] ABSTRACT: The epidermis of swollen storage roots in purple cultivars of turnip “Tsuda” (Brassica rapa) accumulates anthocyanin in a light-dependent manner, especially in response to UV-A light, of which the mechanism is unclear. In this study, we mutagenized 15,000 seeds by 0.5% (v/v) ethyl methane sulfonate (EMS) and obtained 14 mutants with abnormal anthocyanin production in their epidermis of swollen storage roots. These mutants were classified into two groups: the red mutants with constitutive anthocyanin accumulation in their epidermis of storage roots even in underground parts in darkness and the white mutants without anthocyanin accumulation in the epidermis of storage roots in aboveground parts exposed to sunlight. Test cross analysis demonstrated that w9, w68, w204, r15, r21, r30 and r57 contained different mutations responsible for their phenotypic variations. Further genetic analysis of four target mutants (w9, w68, w204 and r15) indicated that each of them was controlled by a different recessive gene. Intriguingly, the expression profiles of anthocyanin biosynthesis genes, including structural and regulatory genes, coincided with their anthocyanin levels in the epidermis of storage roots in the four target mutants. We proposed that potential genes responsible for the mutations should be upstream factors of the anthocyanin biosynthesis pathway in turnips, which provided resources to further investigate the mechanisms of light-induced anthocyanin accumulation.
    Full-text · Article · Jun 2017
    +1 more author...
    Read full-text
    • If all three DHARs are knocked out, GSSG accumulation, whether induced pharmacologically or genetically, is almost completely inhibited (Figs. 6 and 7).Of the three double loss-of-function combinations, the clearest effect on glutathione status was observed for dhar1 dhar2. This underscores the potential importance of the cytosolic isoforms in coupling ascorbate and glutathione pools and is consistent with previous studies demonstrating the importance of cytosolic APX1 or GR1 in cat2-triggered responses (Mhamdi et al., 2010a;Vanderauwera et al., 2011) The importance of the cytosol in this context may be related to the peroxisomal location of the H 2 O 2 that becomes available when catalase is deficient, although decreased glutathione oxidation also was reported for single dhar1 and dhar2 mutants after exposure to high light (Noshi et al., 2017). DHAR3 may be more significant in chloroplastic processing, although our data provide little evidence that this isoform plays a specific role in response to paraquat-induced oxidative stress, which largely originates in this organelle (SupplementalFig.
    [Show abstract] [Hide abstract] ABSTRACT: The complexity of plant antioxidative systems gives rise to many unresolved questions. One relates to the functional importance of dehydroascorbate reductases (DHARs) in interactions between ascorbate and glutathione. To investigate this issue, we produced a complete set of loss-of-function mutants for the three annotated Arabidopsis DHARs. The combined loss of DHAR1 and DHAR3 expression decreased extractable activity to very low levels but had little effect on phenotype or ascorbate and glutathione pools in standard conditions. An analysis of the subcellular localization of the DHARs in Arabidopsis lines stably transformed with GFP fusion proteins revealed that DHAR1 and DHAR2 are cytosolic while DHAR3 is chloroplastic, with no evidence for peroxisomal or mitochondrial localizations. When the mutations were introduced into an oxidative stress genetic background (cat2), the dhar1 dhar2 combination decreased glutathione oxidation and inhibited cat2-triggered induction of the salicylic acid pathway. These effects were reversed in cat2 dhar1 dhar2 dhar3 complemented with any of the three DHARs. The data suggest that (1) DHAR can be decreased to negligible levels without marked effects on ascorbate pools; (2) the cytosolic isoforms are particularly important in coupling intracellular H2O2 metabolism to glutathione oxidation; (3) DHAR-dependent glutathione oxidation influences redox-driven salicylic acid accumulation.
    Full-text · Article · Apr 2017
    +1 more author...
    Read full-text
    • It seems that the acclimation of YL to LL under MoWD operated through an increased PSII quantum efficiency and an increased thermal dissipation that served as a protective regulatory mechanism that reduced excitation pressure. Field-grown A. thaliana plants seem to acclimate to multivariable environmental conditions by adjustments in the stoichiometry of photosystems that allowed the plants to improve their photosynthetic performance by more efficient light utility, lower susceptibility to photoinhibition and reduced photooxidative damage ( Wituszy´nska et al., 2013).
    [Show abstract] [Hide abstract] ABSTRACT: Water deficit stress promotes excitation pressure and photooxidative damage due to an imbalance between light capture and energy use. Young leaves (YL) of Arabidopsis thaliana plants acclimate better to the onset of water deficit (OnsWD) than do mature leaves (ML). To obtain a better understanding of this differential response, we evaluated whether YL and ML of A. thaliana exposed to the OnsWD, mild water deficit (MiWD) and moderate water deficit (MoWD), show differences in their photosynthetic performance, and whether photosynthetic acclimation correlates with leaf developmental stage. Water deficit (WD) resulted in greater photooxidative damage in ML compared to YL, but the latter could not be protected under the OnsWD or MiWD, but only under MoWD. YL of A. thaliana with signs of photosynthetic acclimation under MoWD retained higher maximum quantum yield (Fv/Fm) and decreased reactive oxygen species (ROS) formation. YL under MoWD, show a reduced excitation pressure and a better balance between light capture and photochemical energy use, which contributed to their photoprotection, but only under low light intensity (LL, 130 μmol photons m−2 s−1) and not under high light (HL, 1200 μmol photons m−2 s−1). In conclusion, leaf developmental stage was correlated with photo-oxidative damage and a differential allocation of absorbed light energy in photosystem II (PSII) of Arabidopsis leaves under WD.
    Full-text · Article · May 2014
    Read full-text
    • In our subsequent analysis using transcriptome data from additional S. habrochaites populations, we found that six of the nine candidate stylar genes that may be involved in interspecific UI were ROS pathway genes (Table 4). Surprisingly, only two ROS-linked genes were upregulated in interpopulation UI-competent styles, one of which encodes a DELLA-like transcription factor thatA linear discriminant function was trained on the expression values of LA1777 and LA0407, and then used to classify other accessions as UI or non-UI indirectly inhibits ROS accumulation and restrains cell expansion[84,85]. In sum, these results suggest that ROS production and signaling between pollen and pistil must be held in a tight balance for pollen tubes to successfully grow through styles to reach the ovary.
    [Show abstract] [Hide abstract] ABSTRACT: Background Unilateral incompatibility (UI) is an asymmetric reproductive barrier that unidirectionally prevents gene flow between species and/or populations. UI is characterized by a compatible interaction between partners in one direction, but in the reciprocal cross fertilization fails, generally due to pollen tube rejection by the pistil. Although UI has long been observed in crosses between different species, the underlying molecular mechanisms are only beginning to be characterized. The wild tomato relative Solanum habrochaites provides a unique study system to investigate the molecular basis of this reproductive barrier, as populations within the species exhibit both interspecific and interpopulation UI. Here we utilized a transcriptomic approach to identify genes in both pollen and pistil tissues that may be key players in UI. Results We confirmed UI at the pollen-pistil level between a self-incompatible population and a self-compatible population of S. habrochaites. A comparison of gene expression between pollinated styles exhibiting the incompatibility response and unpollinated controls revealed only a small number of differentially expressed transcripts. Many more differences in transcript profiles were identified between UI-competent versus UI-compromised reproductive tissues. A number of intriguing candidate genes were highly differentially expressed, including a putative pollen arabinogalactan protein, a stylar Kunitz family protease inhibitor, and a stylar peptide hormone Rapid ALkalinization Factor. Our data also provide transcriptomic evidence that fundamental processes including reactive oxygen species (ROS) signaling are likely key in UI pollen-pistil interactions between both populations and species. Conclusions Gene expression analysis of reproductive tissues allowed us to better understand the molecular basis of interpopulation incompatibility at the level of pollen-pistil interactions. Our transcriptomic analysis highlighted specific genes, including those in ROS signaling pathways that warrant further study in investigations of UI. To our knowledge, this is the first report to identify candidate genes involved in unilateral barriers between populations within a species. Electronic supplementary material The online version of this article (doi:10.1186/s12870-017-1032-4) contains supplementary material, which is available to authorized users.
    Full-text · Article · Dec 2017
    +1 more author...
    Read full-text
    • Another possibility is that DEL1 activity is regulated through its 360 phosphorylation, because a predicted CDK phosphorylation motif is present in the N-terminus 361 of the DEL1 protein sequence (SupplementalFig. S5) (Chang et al., 2007).Boudolf et al., 2009), whereas the ERF115 transcription factor was proposed to be a 383 APC/C CCS52A2-specific target in root stem cells (Heyman et al., 2013). A possible method to 384 uncover specific APC/C substrates is by using a biochemical approach.
    [Show abstract] [Hide abstract] ABSTRACT: The endocycle represents a modified mitotic cell cycle that in plants is often coupled to cell enlargement and differentiation. Endocycle onset is controlled by activity of the Anaphase Promoting Complex/Cyclosome (APC/C), a multi-subunit E3 ubiquitin ligase targeting cell cycle factors for destruction. CELL CYCLE SWITCH 52 (CCS52) proteins represent rate-limiting activator subunits of the APC/C. In Arabidopsis thaliana (Arabidopsis), mutations in either CCS52A1 or CCS52A2 activators result in a delayed endocycle onset, whereas their overexpression triggers increased DNA ploidy levels. Here, the relative contribution of the APC/CCCS52A1 and APC/CCCS52A2 complexes to different developmental processes was studied through analysis of their negative regulators, being the ULTRAVIOLET-B-INSENSITIVE 4 (UVI4) protein and the DP-E2F-Like 1 (DEL1) transcriptional repressor, respectively. Our data illustrate cooperative activity of the APC/CCCS52A1 and APC/CCCS52A2 complexes during root and trichome development, but functional interdependency during leaf development. Furthermore, we found APC/CCCS52A1 activity to control CCS52A2 expression. We conclude that interdependency of CCS52A-controlled APC/C activity is controlled in a tissue-specific manner.
    Article · Jul 2017
    Read
    • 4. Unfavourable environmental conditions result in excessive ROS production that leads to oxidative cell injuries at high concentrations. To prevent ROS-dependent cellular damage, plants have a broad range of antioxidant mechanisms at their disposal to use ROS simultaneously as a signal within various biological processes (Vanderauwera et al., 2009). In plants, the homologue of the respiratory-burst NADPH oxidase of leukocytes has been identified (Sagi and Fluhr, 2006), and this has led to the demonstration that plant cells, like mammalian cells, can initiate and most likely amplify ROS production for the purpose of signalling (Suzuki et al.,2011;Marino et al., 2012).
    [Show abstract] [Hide abstract] ABSTRACT: The production of reactive oxygen species (ROS) is the unavoidable consequence of aerobic life. ROS is a collective term that includes both oxygen radicals, like superoxide (O 2. -) and hydroxyl (·OH) radicals, and other non-radicals such as hydrogen peroxide (H2O2), singlet oxygen ((1)O2 or (1)Δg), etc. In plants, ROS are produced in different cell compartments and are oxidizing species, particularly hydroxyl radicals and singlet oxygen, that can produce serious damage in biological systems (oxidative stress). However, plant cells also have an array of antioxidants which, normally, can scavenge the excess oxidants produced and so avoid deleterious effects on the plant cell bio-molecules. The concept of 'oxidative stress' was re-evaluated in recent years and the term 'oxidative signalling' was created. This means that ROS production, apart from being a potentially harmful process, is also an important component of the signalling network that plants use for their development and for responding to environmental challenges. It is known that ROS play an important role regulating numerous biological processes such as growth, development, response to biotic and environmental stresses, and programmed cell death. The term reactive nitrogen species (RNS) includes radicals like nitric oxide (NO· ) and nitric dioxide (NO2.), as well as non-radicals such as nitrous acid (HNO2) and dinitrogen tetroxide (N2O4), among others. RNS are also produced in plants although the generating systems have still not been fully characterized. Nitric oxide (NO·) has an important function as a key signalling molecule in plant growth, development, and senescence, and RNS, like ROS, also play an important role as signalling molecules in the response to environmental (abiotic) stress. Similarly, NO· is a key mediator, in co-operation with ROS, in the defence response to pathogen attacks in plants. ROS and RNS have been demonstrated to have an increasingly important role in biology and medicine.
    Full-text · Article · Apr 2015
    Read full-text
    • ROS homeostasis is regulated by the antagonism between ROS producers and scavengers. Several reports have described the network of ROS signaling genes in Arabidopsis thaliana (Mittler et al., 2004;Gadjev et al., 2006;Miller et al., 2010). Thus, the induction of genes encoding for key enzymes that regulate ROS accumulation, such as superoxide dismutases (SODs), ascorbate peroxidases (APXs), catalases (CATs), and other peroxidases, is necessary to remove excess O @BULLET− 2 and H 2 O 2 and ensure plant survival (Miller et al., 2010).
    Full-text · Article · Jul 2017
    +1 more author...
    Read full-text
    • Upon DNA damage, ATM and ATR activate the WEE1 kinase, which mainly controls the replication checkpoint (De Schutter et al, 2007;Dissmeyer et al, 2009;Cools et al, 2011). The G2/M DNA damage checkpoint is controlled by the CDKA;1 inhibitors, SIAMESE RELATED 5 and 7, direct targets of phosphorylated SOG1 upon DNA damage (Yi et al, 2014).
    [Show abstract] [Hide abstract] ABSTRACT: The rapidly proliferating cells in plant meristems must be protected from genome damage. Here, we show that the regulatory role of the Arabidopsis RETINOBLASTOMA RELATED (RBR) in cell proliferation can be separated from a novel function in safeguarding genome integrity. Upon DNA damage, RBR and its binding partner E2FA are recruited to heterochromatic γH2AX-labelled DNA damage foci in an ATM- and ATR-dependent manner. These γH2AX-labelled DNA lesions are more dispersedly occupied by the conserved repair protein, AtBRCA1, which can also co-localise with RBR foci. RBR and AtBRCA1 physically interact in vitro and in planta Genetic interaction between the RBR-silenced amiRBR and Atbrca1 mutants suggests that RBR and AtBRCA1 may function together in maintaining genome integrity. Together with E2FA, RBR is directly involved in the transcriptional DNA damage response as well as in the cell death pathway that is independent of SOG1, the plant functional analogue of p53. Thus, plant homologs and analogues of major mammalian tumour suppressor proteins form a regulatory network that coordinates cell proliferation with cell and genome integrity.
    Full-text · Article · Mar 2017
    +1 more author...
    Read full-text
    • Comparison of WT and gsnor plants under normal growth condition revealed an enhanced expression of genes involved in antioxidant processes in gsnor plants (Table 1). The up-regulated genes of peroxidases or GSTs are markers for oxidative stress and/or H 2 O 2 signaling (Vanderauwera et al., 2005;Queval et al., 2012). However, little is known about the exact physiological function of these enzymes during oxidative stress.
    [Show abstract] [Hide abstract] ABSTRACT: Nitric oxide (NO) has emerged as a signaling molecule in plants being involved in diverse physiological processes like germination, root growth, stomata closing and response to biotic and abiotic stress. S-nitrosoglutathione (GSNO) as a biological NO donor has a very important function in NO signaling since it can transfer its NO moiety to other proteins (trans-nitrosylation). Such trans-nitrosylation reactions are equilibrium reactions and depend on GSNO level. The breakdown of GSNO and thus the level of S-nitrosylated proteins are regulated by GSNO-reductase (GSNOR). In this way, this enzyme controls S-nitrosothiol levels and regulates NO signaling. Here we report that Arabidopsis thaliana GSNOR activity is reversibly inhibited by H2O2 in vitro and by paraquat-induced oxidative stress in vivo. Light scattering analyses of reduced and oxidized recombinant GSNOR demonstrated that GSNOR proteins form dimers under both reducing and oxidizing conditions. Moreover, mass spectrometric analyses revealed that H2O2-treatment increased the amount of oxidative modifications on Zn2+-coordinating Cys47 and Cys177. Inhibition of GSNOR results in enhanced levels of S-nitrosothiols followed by accumulation of glutathione. Moreover, transcript levels of redox-regulated genes and activities of glutathione-dependent enzymes are increased in gsnor-ko plants, which may contribute to the enhanced resistance against oxidative stress. In sum, our results demonstrate that reactive oxygen species (ROS)-dependent inhibition of GSNOR is playing an important role in activation of anti-oxidative mechanisms to damping oxidative damage and imply a direct crosstalk between ROS- and NO-signaling.
    Full-text · Article · Nov 2016
    +1 more author...
    Read full-text
    • When photoprotective mechanisms in leaves are not sufficient to protect the photosynthetic machinery, photoinhibition takes place and is traceable through the production of reactive oxygen species (ROS) (Mittler et al. 2004). However, a limited and tightly controlled amount of ROS act as signalling molecules (Mullineaux et al. 2006) and are often integrated into signalling pathways, such as the acclimation of plants grown under low light to high light (Kwak et al. 2006; Mittler et al. 2004; Mullineaux et al. 2006).
    [Show abstract] [Hide abstract] ABSTRACT: Worldwide, extensive agricultural losses are attributed to drought, often in combination with heat in Mediterranean climate regions, where grapevine traditionally grows. The available scenarios for climate change suggest increases in aridity in these regions. Under natural conditions plants are affected by a combination of stresses, triggering synergistic or antagonistic physiological, metabolic or transcriptomic responses unique to the combination. However the study of such stresses in a controlled environment can elucidate important mechanisms by allowing the separation of the effects of individual stresses. To gather those effects, cuttings of two grapevine varieties, Touriga Nacional (TN) and Trincadeira (TR), were grown under controlled conditions and subjected to three abiotic stresses (drought, WS, heat, HS and high light, LS) individually and in combination two by two (WSHS, WSLS, HSLS) or the three (WSHSLS). Photosynthesis, water status, contents of H2 O2 , abscisic acid and metabolites of the ascorbate-glutathione cycle were measured in the leaves. Common and distinct response features were identified in the different stress combinations. Photosynthesis was not hindered in TN by LS while even individual stresses severely affect photosynthesis in TR. Abscisic acid may be implicated in grapevine osmotic responses since it is correlated with tolerance parameters especially in combined stresses involving drought. Overall, the responses to drought-including treatments were clearly distinct to those without drought. From the specific behaviors of the varieties, it can be concluded that TN shows a higher capacity for heat dissipation and for withstanding high light intensities, indicating a better adjustment to warm conditions, provided that water supply is plentiful. This article is protected by copyright. All rights reserved.
    Full-text · Article · Oct 2015
    +1 more author...
    Read full-text

Institutions

Publication Stats

7k Citations
Browse more researchers