TY - JOUR A1 - Rauf, Mamoona A1 - Arif, Muhammad A1 - Fisahn, Joachim A1 - Xue, Gang-Ping A1 - Balazadeh, Salma A1 - Müller-Röber, Bernd T1 - NAC transcription factor speedy hyponastic growth regulates flooding-induced leaf movement in arabidopsis JF - The plant cell N2 - In rosette plants, root flooding (waterlogging) triggers rapid upward (hyponastic) leaf movement representing an important architectural stress response that critically determines plant performance in natural habitats. The directional growth is based on localized longitudinal cell expansion at the lower (abaxial) side of the leaf petiole and involves the volatile phytohormone ethylene (ET). We report the existence of a transcriptional core unit underlying directional petiole growth in Arabidopsis thaliana, governed by the NAC transcription factor SPEEDY HYPONASTIC GROWTH (SHYG). Overexpression of SHYG in transgenic Arabidopsis thaliana enhances waterlogging-triggered hyponastic leaf movement and cell expansion in abaxial cells of the basal petiole region, while both responses are largely diminished in shyg knockout mutants. Expression of several EXPANSIN and XYLOGLUCAN ENDOTRANSGLYCOSYLASE/HYDROLASE genes encoding cell wall-loosening proteins was enhanced in SHYG overexpressors but lowered in shyg. We identified ACC OXIDASE5 (ACO5), encoding a key enzyme of ET biosynthesis, as a direct transcriptional output gene of SHYG and found a significantly reduced leaf movement in response to root flooding in aco5 T-DNA insertion mutants. Expression of SHYG in shoot tissue is triggered by root flooding and treatment with ET, constituting an intrinsic ET-SHYG-ACO5 activator loop for rapid petiole cell expansion upon waterlogging. Y1 - 2013 U6 - https://doi.org/10.1105/tpc.113.117861 SN - 1040-4651 SN - 1532-298X VL - 25 IS - 12 SP - 4941 EP - 4955 PB - American Society of Plant Physiologists CY - Rockville ER - TY - JOUR A1 - Alshareef, Nouf Owdah A1 - Otterbach, Sophie L. A1 - Allu, Annapurna Devi A1 - Woo, Yong H. A1 - de Werk, Tobias A1 - Kamranfar, Iman A1 - Müller-Röber, Bernd A1 - Tester, Mark A1 - Balazadeh, Salma A1 - Schmöckel, Sandra M. T1 - NAC transcription factors ATAF1 and ANAC055 affect the heat stress response in Arabidopsis JF - Scientific reports N2 - Pre-exposing (priming) plants to mild, non-lethal elevated temperature improves their tolerance to a later higher-temperature stress (triggering stimulus), which is of great ecological importance. 'Thermomemory' is maintaining this tolerance for an extended period of time. NAM/ATAF1/2/ CUC2 (NAC) proteins are plant-specific transcription factors (TFs) that modulate responses to abiotic stresses, including heat stress (HS). Here, we investigated the potential role of NACs for thermomemory. We determined the expression of 104 Ara bidopsis NAC genes after priming and triggering heat stimuli, and found ATAF1 expression is strongly induced right after priming and declines below control levels thereafter during thermorecovery. Knockout mutants of ATAF1 show better thermomemory than wild type, revealing a negative regulatory role. Differential expression analyses of RNA-seq data from ATAF1 overexpressor, ataf1 mutant and wild-type plants after heat priming revealed five genes that might be priming-associated direct targets of ATAF1: AT2G31260 (ATG9), AT2G41640 (GT61), AT3G44990 (XTH31), AT4G27720 and AT3G23540. Based on co-expression analyses applied to the aforementioned RNA-seq profiles, we identified ANAC055 to be transcriptionally co-regulated with ATAF1. Like atafl, anac055 mutants show improved thermomemory, revealing a potential co-control of both NACTFs over thermomemory. Our data reveals a core importance of two NAC transcription factors, ATAF1 and ANAC055, for thermomemory. Y1 - 2022 U6 - https://doi.org/10.1038/s41598-022-14429-x SN - 2045-2322 VL - 12 IS - 1 PB - Nature Research CY - Berlin ER - TY - JOUR A1 - Omranian, Nooshin A1 - Klie, Sebastian A1 - Müller-Röber, Bernd A1 - Nikoloski, Zoran T1 - Network-based segmentation of biological multivariate time series JF - PLoS one N2 - Molecular phenotyping technologies (e.g., transcriptomics, proteomics, and metabolomics) offer the possibility to simultaneously obtain multivariate time series (MTS) data from different levels of information processing and metabolic conversions in biological systems. As a result, MTS data capture the dynamics of biochemical processes and components whose couplings may involve different scales and exhibit temporal changes. Therefore, it is important to develop methods for determining the time segments in MTS data, which may correspond to critical biochemical events reflected in the coupling of the system's components. Here we provide a novel network-based formalization of the MTS segmentation problem based on temporal dependencies and the covariance structure of the data. We demonstrate that the problem of partitioning MTS data into k segments to maximize a distance function, operating on polynomially computable network properties, often used in analysis of biological network, can be efficiently solved. To enable biological interpretation, we also propose a breakpoint-penalty (BP-penalty) formulation for determining MTS segmentation which combines a distance function with the number/length of segments. Our empirical analyses of synthetic benchmark data as well as time-resolved transcriptomics data from the metabolic and cell cycles of Saccharomyces cerevisiae demonstrate that the proposed method accurately infers the phases in the temporal compartmentalization of biological processes. In addition, through comparison on the same data sets, we show that the results from the proposed formalization of the MTS segmentation problem match biological knowledge and provide more rigorous statistical support in comparison to the contending state-of-the-art methods. Y1 - 2013 U6 - https://doi.org/10.1371/journal.pone.0062974 SN - 1932-6203 VL - 8 IS - 5 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Rauf, Mamoona A1 - Arif, Muhammad A1 - Dortay, Hakan A1 - Matallana-Ramirez, Lilian P. A1 - Waters, Mark T. A1 - Nam, Hong Gil A1 - Lim, Pyung-Ok A1 - Müller-Röber, Bernd A1 - Balazadeh, Salma T1 - ORE1 balances leaf senescence against maintenance by antagonizing G2-like-mediated transcription JF - EMBO reports N2 - Leaf senescence is a key physiological process in all plants. Its onset is tightly controlled by transcription factors, of which NAC factor ORE1 (ANAC092) is crucial in Arabidopsis thaliana. Enhanced expression of ORE1 triggers early senescence by controlling a downstream gene network that includes various senescence-associated genes. Here, we report that unexpectedly ORE1 interacts with the G2-like transcription factors GLK1 and GLK2, which are important for chloroplast development and maintenance, and thereby for leaf maintenance. ORE1 antagonizes GLK transcriptional activity, shifting the balance from chloroplast maintenance towards deterioration. Our finding identifies a new mechanism important for the control of senescence by ORE1. KW - transcription factor KW - senescence KW - chloroplast KW - protein-protein interaction Y1 - 2013 U6 - https://doi.org/10.1038/embor.2013.24 SN - 1469-221X VL - 14 IS - 4 SP - 382 EP - 388 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Riano-Pachon, Diego Mauricio A1 - Dreyer, Ingo A1 - Müller-Röber, Bernd T1 - Orphan transcripts in Arabidopsis thaliana : identification of several hundred previously unrecognized genes N2 - Expressed sequence tags (ESTs) represent a huge resource for the discovery of previously unknown genetic information and functional genome assignment. In this study we screened a collection of 178 292 ESTs from Arabidopsis thaliana by testing them against previously annotated genes of the Arabidopsis genome. We identified several hundreds of new transcripts that match the Arabidopsis genome at so far unassigned loci. The transcriptional activity of these loci was independently confirmed by comparison with the Salk Whole Genome Array Data. To a large extent, the newly identified transcriptionally active genomic regions do not encode 'classic' proteins, but instead generate non-coding RNAs and/or small peptide-coding RNAs of presently unknown biological function. More than 560 transcripts identified in this study are not represented by the Affymetrix GeneChip arrays currently widely used for expression profiling in A. thaliana. Our data strongly support the hypothesis that numerous previously unknown genes exist in the Arabidopsis genome Y1 - 2005 SN - 0960-7412 ER - TY - JOUR A1 - Balazadeh, Salma A1 - Kwasniewski, Miroslaw A1 - Caldana, Camila A1 - Mehrnia, Mohammad A1 - Zanor, Maria Ines A1 - Xue, Gang-Ping A1 - Müller-Röber, Bernd T1 - ORS1, an H2O2-Responsive NAC Transcription Factor, Controls Senescence in Arabidopsis thaliana JF - Molecular plant N2 - We report here that ORS1, a previously uncharacterized member of the NAC transcription factor family, controls leaf senescence in Arabidopsis thaliana. Overexpression of ORS1 accelerates senescence in transgenic plants, whereas its inhibition delays it. Genes acting downstream of ORS1 were identified by global expression analysis using transgenic plants producing dexamethasone-inducible ORS1-GR fusion protein. Of the 42 up-regulated genes, 30 (similar to 70%) were previously shown to be up-regulated during age-dependent senescence. We also observed that 32 (similar to 76%) of the ORS1-dependent genes were induced by long-term (4 d), but not short-term (6 h) salinity stress (150 mM NaCl). Furthermore, expression of 16 and 24 genes, respectively, was induced after 1 and 5 h of treatment with hydrogen peroxide (H2O2), a reactive oxygen species known to accumulate during salinity stress. ORS1 itself was found to be rapidly and strongly induced by H2O2 treatment in both leaves and roots. Using in vitro binding site selection, we determined the preferred binding motif of ORS1 and found it to be present in half of the ORS1-dependent genes. ORS1 is a paralog of ORE1/ANAC092/AtNAC2, a previously reported regulator of leaf senescence. Phylogenetic footprinting revealed evolutionary conservation of the ORS1 and ORE1 promoter sequences in different Brassicaceae species, indicating strong positive selection acting on both genes. We conclude that ORS1, similarly to ORE1, triggers expression of senescence-associated genes through a regulatory network that may involve cross-talk with salt- and H2O2-dependent signaling pathways. KW - NAC transcription factor KW - leaf senescence KW - gene expression KW - gene regulatory network KW - hydrogen peroxide Y1 - 2011 U6 - https://doi.org/10.1093/mp/ssq080 SN - 1674-2052 VL - 4 IS - 2 SP - 346 EP - 360 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Mehterov, Nikolay A1 - Balazadeh, Salma A1 - Hille, Jacques A1 - Toneva, Valentina A1 - Müller-Röber, Bernd A1 - Gechev, Tsanko S. T1 - Oxidative stress provokes distinct transcriptional responses in the stress-tolerant atr7 and stress-sensitive loh2 Arabidopsis thaliana mutants as revealed by multi-parallel quantitative real-time PCR analysis of ROS marker and antioxidant genes JF - Plant physiology and biochemistry : an official journal of the Federation of European Societies of Plant Physiology N2 - The Arabidopsis thaliana atr7 mutant is tolerant to oxidative stress induced by paraquat (PQ) or the catalase inhibitor aminotriazole (AT), while its original background loh2 and wild-type plants are sensitive. Both, AT and PQ which stimulate the intracellular formation of H2O2 or superoxide anions, respectively, trigger cell death in loh2 but do not lead to visible damage in atr7. To study gene expression during oxidative stress and ROS-induced programmed cell death, two platforms for multi-parallel quantitative real-time PCR (qRT-PCR) analysis of 217 antioxidant and 180 ROS marker genes were employed. The qRT-PCR analyses revealed AT- and PQ-induced expression of many ROS-responsive genes mainly in loh2, confirming that an oxidative burst plays a role in the activation of the cell death in this mutant. Some of the genes were specifically regulated by either AT or PQ serving as markers for particular types of ROS. Genes significantly induced by both AT and PQ in loh2 included transcription factors (ANAC042/JUB1, ANAC102, DREB19, HSFA2, RRTF1, ZAT10, ZAT12, ethylene-responsive factors), signaling compounds, ferritins, alternative oxidases, and antioxidant enzymes. Many of these genes were upregulated in atr7 compared to loh2 under non-stress conditions at the first time point, indicating that higher basal levels of ROS and higher antioxidant capacity in atr7 are responsible for the enhanced tolerance to oxidative stress and suggesting a possible tolerance against multiple stresses of this mutant. KW - Antioxidant genes KW - Reactive oxygen species KW - Stress tolerance KW - Transcription analysis Y1 - 2012 U6 - https://doi.org/10.1016/j.plaphy.2012.05.024 SN - 0981-9428 VL - 59 SP - 20 EP - 29 PB - Elsevier CY - Paris ER - TY - JOUR A1 - Omranian, Nooshin A1 - Müller-Röber, Bernd A1 - Nikoloski, Zoran T1 - PageRank-based identification of signaling crosstalk from transcriptomics data the case of Arabidopsis thaliana JF - Molecular BioSystems N2 - The levels of cellular organization, from gene transcription to translation to protein-protein interaction and metabolism, operate via tightly regulated mutual interactions, facilitating organismal adaptability and various stress responses. Characterizing the mutual interactions between genes, transcription factors, and proteins involved in signaling, termed crosstalk, is therefore crucial for understanding and controlling cells' functionality. We aim at using high-throughput transcriptomics data to discover previously unknown links between signaling networks. We propose and analyze a novel method for crosstalk identification which relies on transcriptomics data and overcomes the lack of complete information for signaling pathways in Arabidopsis thaliana. Our method first employs a network-based transformation of the results from the statistical analysis of differential gene expression in given groups of experiments under different signal-inducing conditions. The stationary distribution of a random walk (similar to the PageRank algorithm) on the constructed network is then used to determine the putative transcripts interrelating different signaling pathways. With the help of the proposed method, we analyze a transcriptomics data set including experiments from four different stresses/signals: nitrate, sulfur, iron, and hormones. We identified promising gene candidates, downstream of the transcription factors (TFs), associated to signaling crosstalk, which were validated through literature mining. In addition, we conduct a comparative analysis with the only other available method in this field which used a biclustering-based approach. Surprisingly, the biclustering-based approach fails to robustly identify any candidate genes involved in the crosstalk of the analyzed signals. We demonstrate that our proposed method is more robust in identifying gene candidates involved downstream of the signaling crosstalk for species for which large transcriptomics data sets, normalized with the same techniques, are available. Moreover, unlike approaches based on biclustering, our approach does not rely on any hidden parameters. Y1 - 2012 U6 - https://doi.org/10.1039/c2mb05365a SN - 1742-206X VL - 8 IS - 4 SP - 1121 EP - 1127 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Read, Betsy A. A1 - Kegel, Jessica A1 - Klute, Mary J. A1 - Kuo, Alan A1 - Lefebvre, Stephane C. A1 - Maumus, Florian A1 - Mayer, Christoph A1 - Miller, John A1 - Monier, Adam A1 - Salamov, Asaf A1 - Young, Jeremy A1 - Aguilar, Maria A1 - Claverie, Jean-Michel A1 - Frickenhaus, Stephan A1 - Gonzalez, Karina A1 - Herman, Emily K. A1 - Lin, Yao-Cheng A1 - Napier, Johnathan A1 - Ogata, Hiroyuki A1 - Sarno, Analissa F. A1 - Shmutz, Jeremy A1 - Schroeder, Declan A1 - de Vargas, Colomban A1 - Verret, Frederic A1 - von Dassow, Peter A1 - Valentin, Klaus A1 - Van de Peer, Yves A1 - Wheeler, Glen A1 - Dacks, Joel B. A1 - Delwiche, Charles F. A1 - Dyhrman, Sonya T. A1 - Glöckner, Gernot A1 - John, Uwe A1 - Richards, Thomas A1 - Worden, Alexandra Z. A1 - Zhang, Xiaoyu A1 - Grigoriev, Igor V. A1 - Allen, Andrew E. A1 - Bidle, Kay A1 - Borodovsky, M. A1 - Bowler, C. A1 - Brownlee, Colin A1 - Cock, J. Mark A1 - Elias, Marek A1 - Gladyshev, Vadim N. A1 - Groth, Marco A1 - Guda, Chittibabu A1 - Hadaegh, Ahmad A1 - Iglesias-Rodriguez, Maria Debora A1 - Jenkins, J. A1 - Jones, Bethan M. A1 - Lawson, Tracy A1 - Leese, Florian A1 - Lindquist, Erika A1 - Lobanov, Alexei A1 - Lomsadze, Alexandre A1 - Malik, Shehre-Banoo A1 - Marsh, Mary E. A1 - Mackinder, Luke A1 - Mock, Thomas A1 - Müller-Röber, Bernd A1 - Pagarete, Antonio A1 - Parker, Micaela A1 - Probert, Ian A1 - Quesneville, Hadi A1 - Raines, Christine A1 - Rensing, Stefan A. A1 - Riano-Pachon, Diego Mauricio A1 - Richier, Sophie A1 - Rokitta, Sebastian A1 - Shiraiwa, Yoshihiro A1 - Soanes, Darren M. A1 - van der Giezen, Mark A1 - Wahlund, Thomas M. A1 - Williams, Bryony A1 - Wilson, Willie A1 - Wolfe, Gordon A1 - Wurch, Louie L. T1 - Pan genome of the phytoplankton Emiliania underpins its global distribution JF - Nature : the international weekly journal of science N2 - Coccolithophores have influenced the global climate for over 200 million years(1). These marine phytoplankton can account for 20 per cent of total carbon fixation in some systems(2). They form blooms that can occupy hundreds of thousands of square kilometres and are distinguished by their elegantly sculpted calcium carbonate exoskeletons (coccoliths), rendering them visible from space(3). Although coccolithophores export carbon in the form of organic matter and calcite to the sea floor, they also release CO2 in the calcification process. Hence, they have a complex influence on the carbon cycle, driving either CO2 production or uptake, sequestration and export to the deep ocean(4). Here we report the first haptophyte reference genome, from the coccolithophore Emiliania huxleyi strain CCMP1516, and sequences from 13 additional isolates. Our analyses reveal a pan genome (core genes plus genes distributed variably between strains) probably supported by an atypical complement of repetitive sequence in the genome. Comparisons across strains demonstrate that E. huxleyi, which has long been considered a single species, harbours extensive genome variability reflected in different metabolic repertoires. Genome variability within this species complex seems to underpin its capacity both to thrive in habitats ranging from the equator to the subarctic and to form large-scale episodic blooms under a wide variety of environmental conditions. Y1 - 2013 U6 - https://doi.org/10.1038/nature12221 SN - 0028-0836 SN - 1476-4687 VL - 499 IS - 7457 SP - 209 EP - 213 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Moreno Curtidor, Catalina A1 - Annunziata, Maria Grazia A1 - Gupta, Saurabh A1 - Apelt, Federico A1 - Richard, Sarah Isabel A1 - Kragler, Friedrich A1 - Müller-Röber, Bernd A1 - Olas, Justyna Jadwiga T1 - Physiological profiling of embryos and dormant seeds in two Arabidopsis accessions reveals a metabolic switch in carbon reserve accumulation JF - Frontiers in plant science N2 - In flowering plants, sugars act as carbon sources providing energy for developing embryos and seeds. Although most studies focus on carbon metabolism in whole seeds, knowledge about how particular sugars contribute to the developmental transitions during embryogenesis is scarce. To develop a quantitative understanding of how carbon composition changes during embryo development, and to determine how sugar status contributes to final seed or embryo size, we performed metabolic profiling of hand-dissected embryos at late torpedo and mature stages, and dormant seeds, in two Arabidopsis thaliana accessions with medium [Columbia-0 (Col-0)] and large [Burren-0 (Bur-0)] seed sizes, respectively. Our results show that, in both accessions, metabolite profiles of embryos largely differ from those of dormant seeds. We found that developmental transitions from torpedo to mature embryos, and further to dormant seeds, are associated with major metabolic switches in carbon reserve accumulation. While glucose, sucrose, and starch predominantly accumulated during seed dormancy, fructose levels were strongly elevated in mature embryos. Interestingly, Bur-0 seeds contain larger mature embryos than Col-0 seeds. Fructose and starch were accumulated to significantly higher levels in mature Bur-0 than Col-0 embryos, suggesting that they contribute to the enlarged mature Bur-0 embryos. Furthermore, we found that Bur-0 embryos accumulated a higher level of sucrose compared to hexose sugars and that changes in sucrose metabolism are mediated by sucrose synthase (SUS), with SUS genes acting non-redundantly, and in a tissue-specific manner to utilize sucrose during late embryogenesis. KW - carbon KW - embryo development KW - hexoses KW - metabolites KW - sucrose KW - synthase Y1 - 2020 U6 - https://doi.org/10.3389/fpls.2020.588433 SN - 1664-462X VL - 11 PB - Frontiers Media CY - Lausanne ER -