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Mitogen-activated protein kinase (MAPK) cascades transmit environmental signals and induce stress and defence responses in plants. These signalling cascades are negatively controlled by specific phosphatases of the type 2C Ser/Thr protein phosphatase (PP2C) and dual-specificity phosphatase (DSP) families that inactivate stress-induced MAPKs; however, the interplay between phosphatases of these different types has remained unknown. Our work reveals that different Arabidopsis MAPK phosphatases, the PP2C-type AP2C1 and the DSP-type MKP1, exhibit both specific and overlapping functions in plant stress responses. Each single mutant and ap2c1 mkp1 double mutant displayed enhanced wound-induced activation of MAPKs MPK3, MPK4, and MPK6, as well as induction of a set of transcription factors. Moreover, ap2c1 mkp1 double mutants show an autoimmune-like response, associated with elevated levels the stress hormones salicylic acid and ethylene, and of the phytoalexin camalexin. Interestingly, this phenotype is reduced in ap2c1 mkp1 mpk6 triple mutants, suggesting that the autoimmune-like response is due to MPK6 misregulation. We conclude that the evolutionarily distant MAPK phosphatases AP2C1 and MKP1 contribute crucially to the tight control of MPK6 activity, ensuring appropriately balanced stress signalling and suppression of autoimmune-like responses during plant growth and development.
Zahra Ayatollahi; Vaiva Kazanaviciute; Volodymyr Shubchynskyy; Kotryna Kvederaviciute; Manfred Schwanninger; Wilfried Rozhon; Michael Stumpe; Felix Mauch; Sebastian Bartels; Roman Ulm; Salma Balazadeh; Bernd Mueller-Roeber; Irute Meskiene; Alois Schweighofer. Dual control of MAPK activities by AP2C1 and MKP1 MAPK phosphatases regulates defence responses in Arabidopsis. 2021, 1 .
AMA StyleZahra Ayatollahi, Vaiva Kazanaviciute, Volodymyr Shubchynskyy, Kotryna Kvederaviciute, Manfred Schwanninger, Wilfried Rozhon, Michael Stumpe, Felix Mauch, Sebastian Bartels, Roman Ulm, Salma Balazadeh, Bernd Mueller-Roeber, Irute Meskiene, Alois Schweighofer. Dual control of MAPK activities by AP2C1 and MKP1 MAPK phosphatases regulates defence responses in Arabidopsis. . 2021; ():1.
Chicago/Turabian StyleZahra Ayatollahi; Vaiva Kazanaviciute; Volodymyr Shubchynskyy; Kotryna Kvederaviciute; Manfred Schwanninger; Wilfried Rozhon; Michael Stumpe; Felix Mauch; Sebastian Bartels; Roman Ulm; Salma Balazadeh; Bernd Mueller-Roeber; Irute Meskiene; Alois Schweighofer. 2021. "Dual control of MAPK activities by AP2C1 and MKP1 MAPK phosphatases regulates defence responses in Arabidopsis." , no. : 1.
Brassinosteroids (BRs) are steroid hormones of plants that coordinate fundamental growth and development processes. Their homeostasis is controlled by diverse means, including glucosylation of the bioactive BR brassinolide (BL), which is catalyzed by the UDP-glycosyltransferases UGT73C5 and UGT73C6 and occurs mainly at the C-23 position, Additional evidence had suggested that the resultant BL-23-O-glucoside (BL-23-O-Glc) can be malonylated, but the physiological significance of and enzyme required for this reaction had remained unknown. Here we show that in Arabidopsis thaliana malonylation of BL-23-O-Glc is catalyzed by the acyltransferase PMAT1, which is also known to malonylate phenolic glucosides and lipid amides. Loss of PMAT1 abolished BL-23-O-malonylglucoside formation and enriched BL-23-O-Glc, showing that the enzyme acts on the glucoside. An over-expression of PMAT1 in plants where UGT73C6 was also over-expressed, and thus BL-23-O-Glc formation was promoted, enhanced the symptoms of BR-deficiency of UGT73C6oe plants, providing evidence that PMAT1 contributes to BL inactivation. Based on these results a model is proposed in which PMAT1 acts in the conversion of both endogenous and xenobiotic glucosides, to adjust metabolic homeostasis in spatial and temporal modes.
Sufu Gan; Wilfried Rozhon; Elisabeth Varga; Jyotirmoy Halder; Franz Berthiller; Brigitte Poppenberger. The acyltransferase PMAT1 malonylates brassinolide glucoside. Journal of Biological Chemistry 2021, 296, 100424 .
AMA StyleSufu Gan, Wilfried Rozhon, Elisabeth Varga, Jyotirmoy Halder, Franz Berthiller, Brigitte Poppenberger. The acyltransferase PMAT1 malonylates brassinolide glucoside. Journal of Biological Chemistry. 2021; 296 ():100424.
Chicago/Turabian StyleSufu Gan; Wilfried Rozhon; Elisabeth Varga; Jyotirmoy Halder; Franz Berthiller; Brigitte Poppenberger. 2021. "The acyltransferase PMAT1 malonylates brassinolide glucoside." Journal of Biological Chemistry 296, no. : 100424.
Previous research complemented with results on BIA1 enzymatic activities shows that the enzyme regulates brassinosteroid homeostasis via mono- and diacetylation of castasterone.
Sufu Gan; Wilfried Rozhon; Elisabeth Varga; Simon Josef Unterholzner; Franz Berthiller; Brigitte Poppenberger. The BAHD Acyltransferase BIA1 Uses Acetyl-CoA for Catabolic Inactivation of Brassinosteroids. Plant Physiology 2020, 184, 23 -26.
AMA StyleSufu Gan, Wilfried Rozhon, Elisabeth Varga, Simon Josef Unterholzner, Franz Berthiller, Brigitte Poppenberger. The BAHD Acyltransferase BIA1 Uses Acetyl-CoA for Catabolic Inactivation of Brassinosteroids. Plant Physiology. 2020; 184 (1):23-26.
Chicago/Turabian StyleSufu Gan; Wilfried Rozhon; Elisabeth Varga; Simon Josef Unterholzner; Franz Berthiller; Brigitte Poppenberger. 2020. "The BAHD Acyltransferase BIA1 Uses Acetyl-CoA for Catabolic Inactivation of Brassinosteroids." Plant Physiology 184, no. 1: 23-26.
Chemical inhibitors are invaluable tools for investigating protein function in reverse genetic approaches. Their application bears many advantages over mutant generation and characterization. Inhibitors can overcome functional redundancy, their application is not limited to species for which tools of molecular genetics are available and they can be applied to specific tissues or developmental stages, making them highly convenient for addressing biological questions. The use of inhibitors has helped to elucidate hormone biosynthesis and signaling pathways and here we review compounds that were developed for the plant hormones brassinosteroids (BRs). BRs are steroids that have strong growth-promoting capacities, are crucial for all stages of plant development and participate in adaptive growth processes and stress response reactions. In the last two decades, impressive progress has been made in BR inhibitor development and application, which has been instrumental for studying BR modes of activity and identifying and characterizing key players. Both, inhibitors that target biosynthesis, such as brassinazole, and inhibitors that target signaling, such as bikinin, exist and in a comprehensive overview we summarize knowledge and methodology that enabled their design and key findings of their use. In addition, the potential of BR inhibitors for commercial application in plant production is discussed.
Wilfried Rozhon; Sonia Akter; Atiara Fernandez; Brigitte Poppenberger. Inhibitors of Brassinosteroid Biosynthesis and Signal Transduction. Molecules 2019, 24, 4372 .
AMA StyleWilfried Rozhon, Sonia Akter, Atiara Fernandez, Brigitte Poppenberger. Inhibitors of Brassinosteroid Biosynthesis and Signal Transduction. Molecules. 2019; 24 (23):4372.
Chicago/Turabian StyleWilfried Rozhon; Sonia Akter; Atiara Fernandez; Brigitte Poppenberger. 2019. "Inhibitors of Brassinosteroid Biosynthesis and Signal Transduction." Molecules 24, no. 23: 4372.
Fruit softening in Fragaria (strawberry) is proposed to be associated with the modification of cell wall components such as xyloglucan by the action of cell wall-modifying enzymes. This study focuses on the in vitro and in vivo characterization of two recombinant xyloglucan endotransglucosylase/hydrolases (XTHs) from Fragaria vesca, FvXTH9 and FvXTH6. Mining of the publicly available F. vesca genome sequence yielded 28 putative XTH genes. FvXTH9 showed the highest expression level of all FvXTHs in a fruit transcriptome data set and was selected with the closely related FvXTH6 for further analysis. To investigate their role in fruit ripening in more detail, the coding sequences of FvXTH9 and FvXTH6 were cloned into the vector pYES2 and expressed in Saccharomyces cerevisiae. FvXTH9 and FvXTH6 displayed xyloglucan endotransglucosylase (XET) activity towards various acceptor substrates using xyloglucan as the donor substrate. Interestingly, FvXTH9 showed activity of mixed-linkage glucan:xyloglucan endotransglucosylase (MXE) and cellulose:xyloglucan endotransglucosylase (CXE). The optimum pH of both FvXTH9 and FvXTH6 was 6.5. The prediction of subcellular localization suggested localization to the secretory pathway, which was confirmed by localization studies in Nicotiana tabacum. Overexpression showed that Fragaria × ananassa fruits infiltrated with FvXTH9 and FvXTH6 ripened faster and showed decreased firmness compared with the empty vector control pBI121. Thus FvXTH9 and also FvXTH6 might promote strawberry fruit ripening by the modification of cell wall components.
Lucia D. Witasari; Fong‐Chin Huang; Thomas Hoffmann; Wilfried Rozhon; Stephen C. Fry; Wilfried Schwab. Higher expression of the strawberry xyloglucan endotransglucosylase/hydrolase genesFvXTH9andFvXTH6accelerates fruit ripening. The Plant Journal 2019, 100, 1237 -1253.
AMA StyleLucia D. Witasari, Fong‐Chin Huang, Thomas Hoffmann, Wilfried Rozhon, Stephen C. Fry, Wilfried Schwab. Higher expression of the strawberry xyloglucan endotransglucosylase/hydrolase genesFvXTH9andFvXTH6accelerates fruit ripening. The Plant Journal. 2019; 100 (6):1237-1253.
Chicago/Turabian StyleLucia D. Witasari; Fong‐Chin Huang; Thomas Hoffmann; Wilfried Rozhon; Stephen C. Fry; Wilfried Schwab. 2019. "Higher expression of the strawberry xyloglucan endotransglucosylase/hydrolase genesFvXTH9andFvXTH6accelerates fruit ripening." The Plant Journal 100, no. 6: 1237-1253.
Feeding experiments with stable isotopes are helpful tools for investigation of metabolic fluxes and biochemical pathways. For assessing nitrogen metabolism, the heavier nitrogen isotope, [15N], has been frequently used. In plants, it is usually applied in form of [15N]-nitrate, which is assimilated mainly in leaves. Thus, methods for quantification of the [15N]-nitrate/[14N]-nitrate ratio in leaves are useful for the planning and evaluation of feeding and pulse–chase experiments. Here we describe a simple and sensitive method for determining the [15N]-nitrate to [14N]-nitrate ratio in leaves. Leaf discs (8 mm diameter, approximately 10 mg fresh weight) were sufficient for analysis, allowing a single leaf to be sampled multiple times. Nitrate was extracted with hot water and derivatized with mesitylene in the presence of sulfuric acid to nitromesitylene. The derivatization product was analyzed by gas chromatography–mass spectrometry with electron ionization. Separation of the derivatized samples required only 6 min. The method shows excellent repeatability with intraday and interday standard deviations of less than 0.9 mol%. Using the method, we show that [15N]-nitrate declines in leaves of hydroponically grown Crassocephalum crepidioides, an African orphan crop, with a biological half-life of 4.5 days after transfer to medium containing [14N]-nitrate as the sole nitrogen source.
Sebastian Schramm; Maria Fe Angela Comia Boco; Sarah Manzer; Oliver König; Tong Zhang; Fatima Tuz Zohora Mony; Adebimpe Nafisat Adedeji-Badmus; Brigitte Poppenberger; Wilfried Rozhon. Determination of the [15N]-Nitrate/[14N]-Nitrate Ratio in Plant Feeding Studies by GC–MS. Molecules 2019, 24, 1531 .
AMA StyleSebastian Schramm, Maria Fe Angela Comia Boco, Sarah Manzer, Oliver König, Tong Zhang, Fatima Tuz Zohora Mony, Adebimpe Nafisat Adedeji-Badmus, Brigitte Poppenberger, Wilfried Rozhon. Determination of the [15N]-Nitrate/[14N]-Nitrate Ratio in Plant Feeding Studies by GC–MS. Molecules. 2019; 24 (8):1531.
Chicago/Turabian StyleSebastian Schramm; Maria Fe Angela Comia Boco; Sarah Manzer; Oliver König; Tong Zhang; Fatima Tuz Zohora Mony; Adebimpe Nafisat Adedeji-Badmus; Brigitte Poppenberger; Wilfried Rozhon. 2019. "Determination of the [15N]-Nitrate/[14N]-Nitrate Ratio in Plant Feeding Studies by GC–MS." Molecules 24, no. 8: 1531.
Pyrrolizidine alkaloids (PAs) are heterocyclic secondary metabolites with a typical pyrrolizidine motif predominantly produced by plants as defense chemicals against herbivores. They display a wide structural diversity and occur in a vast number of species with novel structures and occurrences continuously being discovered. These alkaloids exhibit strong hepatotoxic, genotoxic, cytotoxic, tumorigenic, and neurotoxic activities, and thereby pose a serious threat to the health of humans since they are known contaminants of foods including grain, milk, honey, and eggs, as well as plant derived pharmaceuticals and food supplements. Livestock and fodder can be affected due to PA-containing plants on pastures and fields. Despite their importance as toxic contaminants of agricultural products, there is limited knowledge about their biosynthesis. While the intermediates were well defined by feeding experiments, only one enzyme involved in PA biosynthesis has been characterized so far, the homospermidine synthase catalyzing the first committed step in PA biosynthesis. This review gives an overview about structural diversity of PAs, biosynthetic pathways of necine base, and necic acid formation and how PA accumulation is regulated. Furthermore, we discuss their role in plant ecology and their modes of toxicity towards humans and animals. Finally, several examples of PA-producing crop plants are discussed.
Sebastian Schramm; Nikolai Köhler; Wilfried Rozhon. Pyrrolizidine Alkaloids: Biosynthesis, Biological Activities and Occurrence in Crop Plants. Molecules 2019, 24, 498 .
AMA StyleSebastian Schramm, Nikolai Köhler, Wilfried Rozhon. Pyrrolizidine Alkaloids: Biosynthesis, Biological Activities and Occurrence in Crop Plants. Molecules. 2019; 24 (3):498.
Chicago/Turabian StyleSebastian Schramm; Nikolai Köhler; Wilfried Rozhon. 2019. "Pyrrolizidine Alkaloids: Biosynthesis, Biological Activities and Occurrence in Crop Plants." Molecules 24, no. 3: 498.
A genomic segment on maize chromosome 7 influences carbon isotope composition, water use efficiency, and leaf growth sensitivity to drought, possibly by affecting stomatal properties. Climate change is expected to decrease water availability in many agricultural production areas around the globe. Therefore, plants with improved ability to grow under water deficit are urgently needed. We combined genetic, phenomic, and physiological approaches to understand the relationship between growth, stomatal conductance, water use efficiency, and carbon isotope composition in maize (Zea mays L.). Using near-isogenic lines derived from a maize introgression library, we analysed the effects of a genomic region previously identified as affecting carbon isotope composition. We show stability of trait expression over several years of field trials and demonstrate in the phenotyping platform Phenodyn that the same genomic region also influences the sensitivity of leaf growth to evaporative demand and soil water potential. Our results suggest that the studied genomic region affecting carbon isotope discrimination also harbours quantitative trait loci playing a role in maize drought sensitivity possibly via stomatal behaviour and development. We propose that the observed phenotypes collectively originate from altered stomatal conductance, presumably via abscisic acid. The online version of this article (10.1007/s00122-018-3193-4) contains supplementary material, which is available to authorized users.
Viktoriya Avramova; Adel Meziane; Eva Bauer; Sonja Blankenagel; Stella Eggels; Sebastian Gresset; Erwin Grill; Claudiu Niculaes; Milena Ouzunova; Brigitte Poppenberger; Thomas Presterl; Wilfried Rozhon; Claude Welcker; Zhenyu Yang; François Tardieu; Chris-Carolin Schön. Carbon isotope composition, water use efficiency, and drought sensitivity are controlled by a common genomic segment in maize. Theoretical and Applied Genetics 2018, 132, 53 -63.
AMA StyleViktoriya Avramova, Adel Meziane, Eva Bauer, Sonja Blankenagel, Stella Eggels, Sebastian Gresset, Erwin Grill, Claudiu Niculaes, Milena Ouzunova, Brigitte Poppenberger, Thomas Presterl, Wilfried Rozhon, Claude Welcker, Zhenyu Yang, François Tardieu, Chris-Carolin Schön. Carbon isotope composition, water use efficiency, and drought sensitivity are controlled by a common genomic segment in maize. Theoretical and Applied Genetics. 2018; 132 (1):53-63.
Chicago/Turabian StyleViktoriya Avramova; Adel Meziane; Eva Bauer; Sonja Blankenagel; Stella Eggels; Sebastian Gresset; Erwin Grill; Claudiu Niculaes; Milena Ouzunova; Brigitte Poppenberger; Thomas Presterl; Wilfried Rozhon; Claude Welcker; Zhenyu Yang; François Tardieu; Chris-Carolin Schön. 2018. "Carbon isotope composition, water use efficiency, and drought sensitivity are controlled by a common genomic segment in maize." Theoretical and Applied Genetics 132, no. 1: 53-63.
The plant hormone abscisic acid (ABA) regulates many processes, including response to drought, seed dormancy and abscission of leaves and fruits. For maintenance of ABA homeostasis, catabolism of ABA by 8′-hydroxylation and subsequent cyclisation to phaseic acid (PA) is crucial. However, detection of ABA 8′-hydroxylation activity is tedious. We present a simple and rapid method for detection of ABA 8′-hydroxylase activity by cloning cDNAs of interest and expressing the respective protein in yeast. Upon addition of ABA, PA is formed and subsequently quantified in the yeast cell culture supernatant by heart cutting 2D-HPLC or GC-MS.
Stella Eggels; Viktoriya Avramova; Chris-Carolin Schön; Brigitte Poppenberger; Wilfried Rozhon. Assay for abscisic acid 8′-hydroxylase activity of cloned plant cytochrome P450 oxidases in Saccharomyces cerevisiae. Analytical Biochemistry 2018, 553, 24 -27.
AMA StyleStella Eggels, Viktoriya Avramova, Chris-Carolin Schön, Brigitte Poppenberger, Wilfried Rozhon. Assay for abscisic acid 8′-hydroxylase activity of cloned plant cytochrome P450 oxidases in Saccharomyces cerevisiae. Analytical Biochemistry. 2018; 553 ():24-27.
Chicago/Turabian StyleStella Eggels; Viktoriya Avramova; Chris-Carolin Schön; Brigitte Poppenberger; Wilfried Rozhon. 2018. "Assay for abscisic acid 8′-hydroxylase activity of cloned plant cytochrome P450 oxidases in Saccharomyces cerevisiae." Analytical Biochemistry 553, no. : 24-27.
Glutamic and aspartic acid fulfil numerous functions in organisms. They are proteinogenic amino acids, they function as neurotransmitters, and glutamic acid links the citrate cycle with amino acid metabolism. In addition, glutamic acid is a precursor for many bioactive molecules like γ-aminobutyric acid (GABA). In tomatoes, glutamic acid accumulates in ripening fruits. Here we present a simple and rapid method for quantification of glutamate and aspartate in tomatoes. A cleared extract is prepared and 2-aminoadipic acid added as internal standard. Subsequently, the amino acids are derivatised with 2,4-dinitro-1-fluorobenzene under alkaline conditions. The derivatives are separated by ultra-high performance liquid chromatography using a phenyl-hexyl column and 50 mM N-methylmorpholine/acetate buffer pH 7.4 containing 12% acetonitrile as eluent and detected by UV absorption at 363 nm. The whole analysis time including separation and column equilibration takes less than 2.8 min with a flow rate of 1 mL/min and less than 1.6 min with a flow rate of 2 mL/min, making this method suitable for high-throughput applications. The method shows excellent reproducibility with intra- and inter-day SDs of approximately 4% for both aspartic and glutamic acid. Using this method we show that the glutamate/aspartate ratio changes significantly during fruit ripening.
Carlos Agius; Sabine Von Tucher; Brigitte Poppenberger; Wilfried Rozhon. Quantification of Glutamate and Aspartate by Ultra-High Performance Liquid Chromatography. Molecules 2018, 23, 1389 .
AMA StyleCarlos Agius, Sabine Von Tucher, Brigitte Poppenberger, Wilfried Rozhon. Quantification of Glutamate and Aspartate by Ultra-High Performance Liquid Chromatography. Molecules. 2018; 23 (6):1389.
Chicago/Turabian StyleCarlos Agius; Sabine Von Tucher; Brigitte Poppenberger; Wilfried Rozhon. 2018. "Quantification of Glutamate and Aspartate by Ultra-High Performance Liquid Chromatography." Molecules 23, no. 6: 1389.
Sugar and organic acid contents are major factors for tomato fruit flavour and are important breeding traits. Here we provide an improved protocol for accurate quantification of the main sugars, glucose and fructose, and the organic acids, citric acid and malic acid, present in tomato. The tomato extract is spiked with lactose and tricarballylic acid as internal standards and loaded onto a NH2 solid phase extraction (SPE) column. The sugars appear in the flow-through and are subsequently analysed by HPLC using a Nucleodur NH2 column and a refractive index detector. The organic acids bind to the SPE column and are eluted with 400?mM phosphoric acid. For analysis, the organic acids are separated by HPLC using a Nucleodur C18ec column and detected by UV absorption at 210?nm. The method shows excellent inter-day and intra-day reproducibility for glucose, fructose and citric acid with standard deviations of 1–5%. Quantification of citric acid by HPLC and GC–MS showed perfect agreement with a deviation of less than 3%.
Carlos Agius; Sabine von Tucher; Brigitte Poppenberger; Wilfried Rozhon. Quantification of sugars and organic acids in tomato fruits. MethodsX 2018, 5, 537 -550.
AMA StyleCarlos Agius, Sabine von Tucher, Brigitte Poppenberger, Wilfried Rozhon. Quantification of sugars and organic acids in tomato fruits. MethodsX. 2018; 5 ():537-550.
Chicago/Turabian StyleCarlos Agius; Sabine von Tucher; Brigitte Poppenberger; Wilfried Rozhon. 2018. "Quantification of sugars and organic acids in tomato fruits." MethodsX 5, no. : 537-550.
DNA methylation is an epigenetic modification, which contributes to the regulation of gene expression and chromatin organization, and thus plays a role in many aspects of plant life. Here we present three methods for the detection of DNA methylation in plant tissues: high performance liquid chromatography, methylation-sensitive restriction digest followed by quantitative PCR and bisulfite conversion followed by single read sequencing. These methods are complementary and allow analysis of DNA methylation in samples from both model and non-model plant species.
Andreas Finke; Wilfried Rozhon; Ales Pecinka. Analysis of DNA Methylation Content and Patterns in Plants. Advanced Structural Safety Studies 2017, 1694, 277 -298.
AMA StyleAndreas Finke, Wilfried Rozhon, Ales Pecinka. Analysis of DNA Methylation Content and Patterns in Plants. Advanced Structural Safety Studies. 2017; 1694 ():277-298.
Chicago/Turabian StyleAndreas Finke; Wilfried Rozhon; Ales Pecinka. 2017. "Analysis of DNA Methylation Content and Patterns in Plants." Advanced Structural Safety Studies 1694, no. : 277-298.
The developed method is sufficiently sensitive for reproducible detection of jacobine in C. crepidioides. Simple sample preparation and rapid separation allows for quantification of jacobine in plant material in a high-throughput manner. Thus, the method is suitable for genetic screenings and may be applicable for other plant species, for instance Jacobaea maritima. In addition, our results show that C. crepidioides cannot be considered safe for human consumption. Copyright © 2017 John Wiley & Sons, Ltd.
Wilfried Rozhon; Lukas Kammermeier; Sebastian Schramm; Nayeem Towfique; N. Adebimpe Adedeji; S. Adesola Ajayi; Brigitte Poppenberger. Quantification of the Pyrrolizidine Alkaloid Jacobine inCrassocephalum crepidioidesby Cation Exchange High-Performance Liquid Chromatography. Phytochemical Analysis 2017, 29, 48 -58.
AMA StyleWilfried Rozhon, Lukas Kammermeier, Sebastian Schramm, Nayeem Towfique, N. Adebimpe Adedeji, S. Adesola Ajayi, Brigitte Poppenberger. Quantification of the Pyrrolizidine Alkaloid Jacobine inCrassocephalum crepidioidesby Cation Exchange High-Performance Liquid Chromatography. Phytochemical Analysis. 2017; 29 (1):48-58.
Chicago/Turabian StyleWilfried Rozhon; Lukas Kammermeier; Sebastian Schramm; Nayeem Towfique; N. Adebimpe Adedeji; S. Adesola Ajayi; Brigitte Poppenberger. 2017. "Quantification of the Pyrrolizidine Alkaloid Jacobine inCrassocephalum crepidioidesby Cation Exchange High-Performance Liquid Chromatography." Phytochemical Analysis 29, no. 1: 48-58.
PHW126 belongs to a small group of rolling circle plasmids. So far, the region mediating autonomous replication has been identified and it was shown that the rep gene is required for replication. However, the regulation of rep expression remained elusive. Here evidence is presented that expression of the replication gene rep is auto-regulated. Sequence analysis revealed a conserved stretch in the rep promoter consisting of three imperfect direct repeats (DR2.1, DR2.2 and DR2.3). Assays for promoter activity showed that these direct repeats act as an enhancer of transcriptional activity. Interestingly, the activating effect was reduced in the presence of Rep protein. Electrophoretic mobility shift assays demonstrated that the Rep protein can directly bind to direct repeats DR2.1 and DR2.3 while DR2.2 is not bound but places DR2.1 and DR2.3 in an appropriate distance. These results show that the synthesis of Rep protein is auto-regulated. In the absence of Rep protein the promoter is, due to the presence of the direct repeats acting as a transcriptional enhancer, highly active. Binding of Rep to the direct repeats reduces the transcription rate significantly. Since this regulation mechanism is independent of a specialised regulator protein it is presumably a very economic strategy.
Wilfried Rozhon. The replication protein of pHW126 auto-controls its expression. Plasmid 2017, 90, 38 -43.
AMA StyleWilfried Rozhon. The replication protein of pHW126 auto-controls its expression. Plasmid. 2017; 90 ():38-43.
Chicago/Turabian StyleWilfried Rozhon. 2017. "The replication protein of pHW126 auto-controls its expression." Plasmid 90, no. : 38-43.
Most signaling cascades ultimately lead to changes in gene expression by modulating the activity of transcription factors (TFs). The electrophoretic mobility shift assay (EMSA) is a simple but powerful in vitro method for investigation of specific protein–DNA interactions. It makes use of the fact that protein–DNA complexes have a lower electrophoretic mobility in gels than free DNA has. The application of labeled probes in combination with unlabeled competitors allows investigation of DNA-binding specificity and identification of binding motifs with single base-pair resolution. Here we describe the application of EMSAs for the study of interactions of the brassinosteroid-regulated TFs, BRASSINAZOLE-RESISTANT1, (BZR1), BRI1-ETHYL METHANESULFONATE-SUPPRESSOR1 (BES1)/BZR2, and CESTA with putative binding sites. The classical approach using radiolabeled probes, as well as the more recent application of fluorescent probes, is described and the advantages and disadvantages of both methods are discussed.
Simon J. Unterholzner; Wilfried Rozhon; Brigitte Poppenberger. Analysis of In Vitro DNA Interactions of Brassinosteroid-Controlled Transcription Factors Using Electrophoretic Mobility Shift Assay. Advanced Structural Safety Studies 2017, 1564, 133 -144.
AMA StyleSimon J. Unterholzner, Wilfried Rozhon, Brigitte Poppenberger. Analysis of In Vitro DNA Interactions of Brassinosteroid-Controlled Transcription Factors Using Electrophoretic Mobility Shift Assay. Advanced Structural Safety Studies. 2017; 1564 ():133-144.
Chicago/Turabian StyleSimon J. Unterholzner; Wilfried Rozhon; Brigitte Poppenberger. 2017. "Analysis of In Vitro DNA Interactions of Brassinosteroid-Controlled Transcription Factors Using Electrophoretic Mobility Shift Assay." Advanced Structural Safety Studies 1564, no. : 133-144.
Brassinosteroids (BRs) are growth-promoting plant hormones that play a role in abiotic stress responses, but molecular modes that enable this activity remain largely unknown. Here we show that BRs participate in the regulation of freezing tolerance. BR signaling-defective mutants of Arabidopsis thaliana were hypersensitive to freezing before and after cold acclimation. The constitutive activation of BR signaling, in contrast, enhanced freezing resistance. Evidence is provided that the BR-controlled basic helix–loop–helix transcription factor CESTA (CES) can contribute to the constitutive expression of the C-REPEAT/DEHYDRATION-RESPONSIVE ELEMENT BINDING FACTOR (CBF) transcriptional regulators that control cold responsive (COR) gene expression. In addition, CBF-independent classes of BR-regulated COR genes are identified that are regulated in a BR- and CES-dependent manner during cold acclimation. A model is presented in which BRs govern different cold-responsive transcriptional cascades through the posttranslational modification of CES and redundantly acting factors. This contributes to the basal resistance against freezing stress, but also to the further improvement of this resistance through cold acclimation.
Marina Eremina; Simon J. Unterholzner; Ajith I. Rathnayake; Marcos Castellanos; Mamoona Khan; Karl G. Kugler; Sean T. May; Klaus F. X. Mayer; Wilfried Rozhon; Brigitte Poppenberger. Brassinosteroids participate in the control of basal and acquired freezing tolerance of plants. Proceedings of the National Academy of Sciences 2016, 113, E5982 -E5991.
AMA StyleMarina Eremina, Simon J. Unterholzner, Ajith I. Rathnayake, Marcos Castellanos, Mamoona Khan, Karl G. Kugler, Sean T. May, Klaus F. X. Mayer, Wilfried Rozhon, Brigitte Poppenberger. Brassinosteroids participate in the control of basal and acquired freezing tolerance of plants. Proceedings of the National Academy of Sciences. 2016; 113 (40):E5982-E5991.
Chicago/Turabian StyleMarina Eremina; Simon J. Unterholzner; Ajith I. Rathnayake; Marcos Castellanos; Mamoona Khan; Karl G. Kugler; Sean T. May; Klaus F. X. Mayer; Wilfried Rozhon; Brigitte Poppenberger. 2016. "Brassinosteroids participate in the control of basal and acquired freezing tolerance of plants." Proceedings of the National Academy of Sciences 113, no. 40: E5982-E5991.
ALTERED MERISTEM PROGRAM1 (AMP1) is a member of the M28 family of carboxypeptidases with a pivotal role in plant development and stress adaptation. Its most prominent mutant defect is a unique hypertrophic shoot phenotype combining a strongly increased organ formation rate with enhanced meristem size and the formation of ectopic meristem poles. However, so far the role of AMP1 in shoot development could not be assigned to a specific molecular pathway nor is its biochemical function resolved. In this work we evaluated the level of functional conservation between AMP1 and its human homolog HsGCPII, a tumor marker of medical interest. We show that HsGCPII cannot substitute AMP1 in planta and that an HsGCPII-specific inhibitor does not evoke amp1-specific phenotypes. We used a chemical genetic approach to identify the drug hyperphyllin (HP), which specifically mimics the shoot defects of amp1, including plastochron reduction and enlargement and multiplication of the shoot meristem. We assessed the structural requirements of HP activity and excluded that it is a cytokinin analog. HP-treated wild-type plants showed amp1-related tissue-specific changes of various marker genes and a significant transcriptomic overlap with the mutant. HP was ineffective in amp1 and elevated the protein levels of PHAVOLUTA, consistent with the postulated role of AMP1 in miRNA-controlled translation, further supporting an AMP1-related mode of action. Our work suggests that plant and animal members of the M28 family of proteases adopted unrelated functions. With HP we provide a tool to characterize the plant-specific functions of this important class of proteins.
Olena Poretska; Saiqi Yang; Delphine Pitorre; Wilfried Rozhon; Karin Zwerger; Marcos Castellanos Uribe; Sean May; Peter McCourt; Brigitte Poppenberger; Tobias Sieberer. The small molecule hyperphyllin enhances leaf formation rate and mimics shoot meristem integrity defects associated with AMP1 deficiency. Plant Physiology 2016, 171, 1277 -1290.
AMA StyleOlena Poretska, Saiqi Yang, Delphine Pitorre, Wilfried Rozhon, Karin Zwerger, Marcos Castellanos Uribe, Sean May, Peter McCourt, Brigitte Poppenberger, Tobias Sieberer. The small molecule hyperphyllin enhances leaf formation rate and mimics shoot meristem integrity defects associated with AMP1 deficiency. Plant Physiology. 2016; 171 (2):1277-1290.
Chicago/Turabian StyleOlena Poretska; Saiqi Yang; Delphine Pitorre; Wilfried Rozhon; Karin Zwerger; Marcos Castellanos Uribe; Sean May; Peter McCourt; Brigitte Poppenberger; Tobias Sieberer. 2016. "The small molecule hyperphyllin enhances leaf formation rate and mimics shoot meristem integrity defects associated with AMP1 deficiency." Plant Physiology 171, no. 2: 1277-1290.
Simon Josef Unterholzner; Wilfried Rozhon; Brigitte Poppenberger. Reply: Interaction between Brassinosteroids and Gibberellins: Synthesis or Signaling? In Arabidopsis, Both! The Plant Cell 2016, 28, 836 -839.
AMA StyleSimon Josef Unterholzner, Wilfried Rozhon, Brigitte Poppenberger. Reply: Interaction between Brassinosteroids and Gibberellins: Synthesis or Signaling? In Arabidopsis, Both! The Plant Cell. 2016; 28 (4):836-839.
Chicago/Turabian StyleSimon Josef Unterholzner; Wilfried Rozhon; Brigitte Poppenberger. 2016. "Reply: Interaction between Brassinosteroids and Gibberellins: Synthesis or Signaling? In Arabidopsis, Both!" The Plant Cell 28, no. 4: 836-839.
Cold stress responses in plants are highly sophisticated events that alter the biochemical composition of cells for protection from damage caused by low temperatures. In addition, cold stress has a profound impact on plant morphologies, causing growth repression and reduced yields. Complex signalling cascades are utilised to induce changes in cold-responsive gene expression that enable plants to withstand chilling or even freezing temperatures. These cascades are governed by the activity of plant hormones, and recent research has provided a better understanding of how cold stress responses are integrated with developmental pathways that modulate growth and initiate other events that increase cold tolerance. Information on the hormonal control of cold stress signalling is summarised to highlight the significant progress that has been made and indicate gaps that still exist in our understanding.
Marina Eremina; Wilfried Rozhon; Brigitte Poppenberger. Hormonal control of cold stress responses in plants. Cellular and Molecular Life Sciences (CMLS) 2015, 73, 797 -810.
AMA StyleMarina Eremina, Wilfried Rozhon, Brigitte Poppenberger. Hormonal control of cold stress responses in plants. Cellular and Molecular Life Sciences (CMLS). 2015; 73 (4):797-810.
Chicago/Turabian StyleMarina Eremina; Wilfried Rozhon; Brigitte Poppenberger. 2015. "Hormonal control of cold stress responses in plants." Cellular and Molecular Life Sciences (CMLS) 73, no. 4: 797-810.
Plant growth and development are highly regulated processes that are coordinated by hormones including the brassinosteroids (BRs), a group of steroids with structural similarity to steroid hormones of mammals. Although it is well understood how BRs are produced and how their signals are transduced, BR targets, which directly confer the hormone’s growth-promoting effects, have remained largely elusive. Here, we show that BRs regulate the biosynthesis of gibberellins (GAs), another class of growth-promoting hormones, in Arabidopsis thaliana. We reveal that Arabidopsis mutants deficient in BR signaling are severely impaired in the production of bioactive GA, which is correlated with defective GA biosynthetic gene expression. Expression of the key GA biosynthesis gene GA20ox1 in the BR signaling mutant bri1-301 rescues many of its developmental defects. We provide evidence that supports a model in which the BR-regulated transcription factor BES1 binds to a regulatory element in promoters of GA biosynthesis genes in a BR-induced manner to control their expression. In summary, our study underscores a role of BRs as master regulators of GA biosynthesis and shows that this function is of major relevance for the growth and development of vascular plants.
Simon Josef Unterholzner; Wilfried Rozhon; Michael Papacek; Jennifer Ciomas; Theo Lange; Karl G. Kugler; Klaus Mayer; Tobias Sieberer; Brigitte Poppenberger. Brassinosteroids Are Master Regulators of Gibberellin Biosynthesis in Arabidopsis. The Plant Cell 2015, 27, 2261 -2272.
AMA StyleSimon Josef Unterholzner, Wilfried Rozhon, Michael Papacek, Jennifer Ciomas, Theo Lange, Karl G. Kugler, Klaus Mayer, Tobias Sieberer, Brigitte Poppenberger. Brassinosteroids Are Master Regulators of Gibberellin Biosynthesis in Arabidopsis. The Plant Cell. 2015; 27 (8):2261-2272.
Chicago/Turabian StyleSimon Josef Unterholzner; Wilfried Rozhon; Michael Papacek; Jennifer Ciomas; Theo Lange; Karl G. Kugler; Klaus Mayer; Tobias Sieberer; Brigitte Poppenberger. 2015. "Brassinosteroids Are Master Regulators of Gibberellin Biosynthesis in Arabidopsis." The Plant Cell 27, no. 8: 2261-2272.