Exogenous classic phytohormones have limited regulatory effects on fructan and primary carbohydrate metabolism in perennial ryegrass (<i>Lolium perenne</i> L.)

Fructans are polymers of fructose and one of the main constituents of water-soluble carbohydrates in forage grasses and cereal crops of temperate climates. Fructans are involved in cold and drought resistance, regrowth following defoliation and early spring growth, seed filling, have beneficial effects on human health and are used for industrial processes. Perennial ryegrass (Lolium perenne L.) serves as model species to study fructan metabolism. Fructan metabolism is under the control of both synthesis by fructosyltransferases (FTs) and breakdown through fructan exohydrolases (FEHs). The accumulation of fructans can be triggered by high sucrose levels and abiotic stress conditions such as drought and cold stress. However, detailed studies on the mechanisms involved in the regulation of fructan metabolism are scarce. Since different phytohormones, especially abscisic acid (ABA), are known to play an important role in abiotic stress responses, the possible short term regulation of the enzymes involved in fructan metabolism by the five classical phytohormones was investigated. Therefore, the activities of enzymes involved in fructan synthesis and breakdown, the expression levels for the corresponding genes and levels for water-soluble carbohydrates were determined following pulse treatments with ABA, auxin (AUX), ethylene (ET), gibberellic acid (GA), or kinetin (KIN). The most pronounced fast effects were a transient increase of I- I activities by AUX, KIN, ABA, and ET, while minor effects were evident for 1-FEH activity with an increased activity in response to KIN and a decrease by GA. Fructan and sucrose levels were not affected. This observed discrepancy demonstrates the importance of determining enzyme activities to obtain insight into the physiological traits and ultimately the plant phenotype. The comparative analyses of activities for seven key enzymes of primary carbohydrate metabolism revealed no co-regulation between enzymes of the fructan and sucrose pool

Floral displays suffer from sulphur deprivation

Nutrient deficiency is known to constrain plant growth in numerous ways, but how it impacts floral displays and pollination success remains unclear. Here we investigate how insufficient availability of sulphur – a vital plant nutrient that is a limiting factor in natural and agricultural regions throughout the world – influences the production of floral displays in Brassica rapa, Physalis philadelphica and three Petunia species with differently coloured flowers. Sulphur deficiency led to a drastic reduction in the number of open flowers, an aberrant flower morphology and smaller pollen with an altered mineral nutrient content. Intriguingly, sulphur deprivation also led to a clear reduction in pigmentation of yellow flowers, but not in flowers with white, purple and red colours. The pale yellow flower colour was due to decreased amounts of violaxanthin, lutein and other carotenoids, suggesting that the carotenoid synthesis pathway is particularly susceptible to sulphur deficiency. Additional experiments with nitrogen and phosphorus depletion confirmed that observed colour and morphological changes were not a general nutrient limitation response, but could be ascribed to sulphur depletion specifically. Taken together, our results showed that (mild) sulphur deficiency deteriorates a suite of floral traits, and that the effects may cascade to pollinators and so have the potential to undermine (agro-)ecosystem functioning.<br/

Comparison of light condition-dependent differences in the accumulation and subcellular localization of glutathione in arabidopsis and wheat

This study aimed to clarify whether the light condition-dependent changes in the redox state and subcellular distribution of glutathione were similar in the dicotyledonous model plant Arabidopsis (wild-type, ascorbate-and glutathione-deficient mutants) and the monocotyledonous crop species wheat (Chinese Spring variety). With increasing light intensity, the amount of its reduced (GSH) and oxidized (GSSG) form and the GSSG/GSH ratio increased in the leaf extracts of both species including all genotypes, while far-red light increased these parameters only in wheat except for GSH in the GSH-deficient Arabidopsis mutant. Based on the expression changes of the glutathione metabolism-related genes, light intensity influences the size and redox state of the glu-tathione pool at the transcriptional level in wheat but not in Arabidopsis. In line with the results in leaf extracts, a similar inducing effect of both light intensity and far-red light was found on the total glutathione content at the subcellular level in wheat. In contrast to the leaf extracts, the inducing influence of light intensity on glutathione level was only found in the cell compartments of the GSH-deficient Arabidopsis mutant, and far-red light increased it in both mutants. The observed general and genotype-specific, light-dependent changes in the accumulation and subcellular distribution of glutathione participate in adjusting the redox-dependent metabolism to the actual environmental conditions. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Architectural space in postmodern America: A case study about the constitution of space in the course of history and its cultural condition

The main concern of this thesis is the establishment of a conceptual framework for the investigation of architectural space. Despite the common negligence in popular critique, my observation of current architecture in America shows both its dependency on, and evolution from, traditional space concepts (premodern and modern space) as well as its significance as a primary means of current architectural expression. Based on the analysis of four museum projects (High Museum in Atlanta - Richard Meier, Aerospace Museum in Los Angeles - Frank Gehry, and two projects for the Ohio State University Center of Visual Arts; CVA - Peter Eisenman, and the CVA competition entry - Michael Graves) an attempt is made to extract common features that characterize present attitudes toward space. Finally, the spectrum of different interpretations which comprise a new, pluralistic system of ordering principles, is put in the context of broader cultural conditions. This correlation (spatial expression - social environment) gives evidence of the interdependence of architecture and common phenomena of the American culture

Potential of enzyme activity assays for physiological phenotyping in perennial ryegrass (Lolium perenne L.)

Die Identifizierung von Genotypen, die hohe Erträge bei gleichzeitiger Toleranz zum Beispiel gegenüber ungünstigen klimatischen Bedingungen aufweisen, ist ein Ziel der Pflanzenzüchtung. "Physiological Phenotyping" ermöglicht die Identifizierung von geeigneten Markern und / oder gewünschten Eigenschaften.Hochzucker-Sorten von Deutsch Weidelgras (Lolium perenne L.), gelten als besonders geeignet, Stickstoffaustritt und Stickoxidemissionen von Weideflächen zu verringern und damit zur Verlangsamung des Klimawandels beizutragen. Bisher wurden Individuen anhand des Gehalts löslicher Zucker oder genomischer Marker bestimmt. Diese Arbeit untersucht erstmals das Potential von Enzymaktivitätsassays. Die Akkumulierung löslicher Zucker hängt in Deutsch Weidelgras von der vorhandenen Saccharose Menge ab. Daher wurde das Marker Potential von Fruktan 1-Exohydrolase (1-FEH, Freisetzung von Fruktose für die Re-Synthese von Saccharose); Zellwand gebundener Invertase, cytoplasmatischer Invertase und vakuolärer Invertase (Saccarose Abbau); Aldolase, Fruktokinase, Hexokinase, Phosphofruktokinase, Phosphoglucose Isomerase (PGI), Phosphoglucose Mutase, UDP-Glukose Pyrophosphorylase (Katalyse intermediärer Schritte der Saccharose Re-Synthese) und Glukose-6-phosphat Dehydrogenase (Kompetition für das limitierende Co-Substrat der Saccharose Re-Synthese), Aktivität unter dem Einfluss von Phytohormonen oder Kälte analysiert.Die etablierte Enzymaktivitätsbestimmung eignet sich zur Identifizierung von Markern, Isoenzymen (Invertasen, Fruktanexohydrolasen) und Eigenschaften in mehreren Modell- und Nutzpflanzen. Weiters wurden mittels Kältebehandlung und Enzymaktiviäten zwei potentielle Marker für Hochzucker-Sorten identifiziert: 1-FEH und PGI Aktivität. Darüber hinaus zeigten sich unterschiedliche Strategien für den Nachschub an Saccharose während der Fruktan-Akkumulation. Dabei handelt es sich um wertvolle Erkenntnisse für die Grundlagenforschung als auch für zukünftige Züchtungsvorhaben.Identifying genotypes with increased crop yield potential and high tolerance e.g. for unfavourable climatic conditions is one major aim in plant breeding. Physiological phenotyping is supposed to be well suited for marker and / or trait identification.Minimizing nitrogen leakage and nitrous oxide emissions from pastures is of major interest in slowing global climate change. High sugar varieties of perennial ryegrass (Lolium perenne L.) are sought to help reducing nitrogen leakage and nitrous oxide emissions from pastures to slow global climate change. So far, metabolite levels and genetic markers were used for candidate plant identification. This study aimed for the first time at verifying the potential of enzyme activity assays. High sugar accumulation in perennial ryegrass is dependent on sucrose supply. Therefore, we analyzed the potential of fructan 1-exohydrolase (1-FEH, releasing fructose for sucrose re-synthesis); cell wall bound, cytoplasmic and vacuolar invertase (degrading sucrose); aldolase, fructokinase, hexokinase, phosphofructokinase, phosphoglucose isomerase (PGI), phosphoglucose mutase, UDP-glucose pyrophosphorylase (catalyzing intermediate steps of sucrose re-synthesis) and glucose-6-phosphate dehydrogenase (competing for the rate limiting co-substrate of sucrose re-synthesis) activity under the influence of plant hormones or cold to induce fructan accumulation.The results presented in this study prove for the first time that the established miniaturized enzyme activity assays are suitable for marker, isozyme (invertases, fructan exohydrolases), and candidate plant identification in several model and crop plants. Further, cold treatment and enzyme activity assays revealed two potential markers for the high sugar trait (1-FEH and PGI activity) and different physiological strategies to maintain high sucrose supply under fructan accumulating conditions in perennial ryegrass, which is of great interest for basic research and breeding.Anna GasperlKumulative Dissertation aus 3 ArtikelnZusammenfassung in deutscher SpracheKarl-Franzens-Universität Graz, Dissertation, 2017OeBB(VLID)220045

Organelle-specific localization of glutathione in plants grown under different light intensities and spectra

Plant ascorbate and glutathione metabolism counteracts oxidative stress mediated, for example, by excess light. In this review, we discuss the properties of immunocytochemistry and transmission electron microscopy, redox-sensitive dyes or probes and bright-field microscopy, confocal microscopy or fluorescence microscopy for the visualization and quantification of glutathione at the cellular or subcellular level in plants and the quantification of glutathione from isolated organelles. In previous studies, we showed that subcellular ascorbate and glutathione levels in Arabidopsis are affected by high light stress. The use of light-emitting diodes (LEDs) is gaining increasing importance in growing indoor crops and ornamental plants. A combination of different LED types allows custom-made combinations of wavelengths and prevents damage related to high photon flux rates. In this review we provide an overview on how different light spectra and light intensities affect glutathione metabolism at the cellular and subcellular levels in plants. Findings obtained in our most recent study demonstrate that both light intensity and spectrum significantly affected glutathione metabolism in wheat at the transcriptional level and caused genotype-specific reactions in the investigated Arabidopsis lines. © 2022, The Author(s)

ÖAW-Gschliefgraben-Symposium Proceedings vom 1. April 2009

In den Jahren 2004-2007 wurde mit Fördermitteln der Internationalen Forschungsprogramme der Österreichischen Akademie der Wissenschaften (Geophysik der Erdkruste, International Strategy for Disaster Reduction) im Gschliefgraben bei Gmunden/OÖ ein umfangreiches geologisch-geophysikalisches Forschungsprojekt verwirklicht. Die Untersuchungen wurden von der Montanuniversität Leoben (Lehrstuhl für Geophysik, Projektleiter: Univ. Prof. Dr. Karl Millahn), dem Joanneum Research Leoben und dem Erkudok-Institut in den K-Hof Museen von Gmunden durchgeführt

A Simple and Fast Kinetic Assay for the Determination of Fructan Exohydrolase Activity in Perennial Ryegrass (Lolium perenne L.)

International audienceDespite the fact that fructans are the main constituent of water-soluble carbohydrates in forage grasses and cereal crops of temperate climates, little knowledge is available on the regulation of the enzymes involved in fructan metabolism. The analysis of enzyme activities involved in this process has been hampered by the low affinity of the fructan enzymes for sucrose and fructans used as fructosyl donor. Further, the analysis of fructan composition and enzyme activities is restricted to specialized labs with access to suited HPLG equipment and appropriate fructan standards. The degradation of fructan polymers with high degree of polymerization (DP) by fructan exohydrolases (FEHs) to fructosyloligomers is important to liberate energy in the form of fructan, but also under conditions where the generation of low DP polymers is required. Based on published protocols employing enzyme coupled endpoint reactions in single cuvettes, we developed a simple and fast kinetic 1-FEH assay. This assay can be performed in multi-well plate format using plate readers to determine the activity of 1-FEH against 1-kestotriose, resulting in a significant time reduction. Kinetic assays allow an optimal and more precise determination of enzyme activities compared to endpoint assays, and enable to check the quality of any reaction with respect to linearity of the assay. The enzyme coupled kinetic 1-FEH assay was validated in a case study showing the expected increase in 1-FEH activity during cold treatment. This assay is cost effective and could be performed by any lab with access to a plate reader suited for kinetic measurements and readings at 340 nm, and is highly suited to assess temporal changes and relative differences in 1-FEH activities. Thus, this enzyme coupled kinetic 1-FEH assay is of high importance both to the field of basic fructan research and plant breeding