Hormonal cross-talk in plant development and stress responses

In contrast to animals, plants can continuously cease and resumegrowth. This flexibility in their architecture and growth patterns ispartly achieved by the action of plant hormones. Plant hormonesare structurally diverse compounds that act usually at nanomolarconcentrations and include five groups of the so-called "clas-sic" hormones, namely auxins, cytokinins, gibberellins, abscisicacid, and ethylene. Jasmonates, salicylates, strigolactones, brassi-nosteroids, polyamines, and some peptides were recognized asnew families of plant hormones. Hormones build a signalingnetwork and mutually regulate several signaling and metabolicsystems, which are essential both for plant development and plantresponses to biotic and abiotic stresses. Although earlier workgreatly advanced our knowledge of how hormones affect plantgrowth and development and stress responses focusing on a singlecompound, it is now evident that physiological processes are reg-ulated in a complex way by the cross-talk of several hormones.In this Research Topic, we aim at collecting a comprehensiveset of original research and review papers focused on hormonalcrosstalk in plants

Rapid and sensitive hormonal profiling of complex plant samples by liquid chromatography coupled to electrospray ionization tandem mass spectrometry

Background Plant hormones play a pivotal role in several physiological processes during a plant's life cycle, from germination to senescence, and the determination of endogenous concentrations of hormones is essential to elucidate the role of a particular hormone in any physiological process. Availability of a sensitive and rapid method to quantify multiple classes of hormones simultaneously will greatly facilitate the investigation of signaling networks in controlling specific developmental pathways and physiological responses. Due to the presence of hormones at very low concentrations in plant tissues (10-9 M to 10-6 M) and their different chemistries, the development of a high-throughput and comprehensive method for the determination of hormones is challenging. Results The present work reports a rapid, specific and sensitive method using ultrahigh-performance liquid chromatography coupled to electrospray ionization tandem spectrometry (UPLC/ESI-MS/MS) to analyze quantitatively the major hormones found in plant tissues within six minutes, including auxins, cytokinins, gibberellins, abscisic acid, 1-amino-cyclopropane-1-carboxyic acid (the ethylene precursor), jasmonic acid and salicylic acid. Sample preparation, extraction procedures and UPLC-MS/MS conditions were optimized for the determination of all plant hormones and are summarized in a schematic extraction diagram for the analysis of small amounts of plant material without time-consuming additional steps such as purification, sample drying or re-suspension. Conclusions This new method is applicable to the analysis of dynamic changes in endogenous concentrations of hormones to study plant developmental processes or plant responses to biotic and abiotic stresses in complex tissues. An example is shown in which a hormone profiling is obtained from leaves of plants exposed to salt stress in the aromatic plant, Rosmarinus officinalis

Was ist gute Hochschullehre? Befunde aus der Hattie-Studie

StudieDie Vorstellungen davon, was gute Lehre ist bzw. gute Lehre ausmacht, gehen weit auseinander und sind zeitlichen Trends und Ideologien unterworfen. Die Frage, die sich zwangsläufig stellt, ist, welchen Orientierungsrahmen es für Hochschullehrende gibt bzw. auf welchen Prinzipien Lehre an einer Hochschule aufbauen kann und muss. Aktuelle Studien – wie die vielbeachtete Metanalyse von Hattie - zeigen vor allem eines: Es gibt nicht eine spezifische Methode oder ein bestimmtes Tool, das den Unterricht verbessert. Lehren und Lernen ist ein komplexer, hochgradig kontext-sensitiver Prozess, der vielen Einflüssen ausgesetzt ist. Deshalb soll nicht von einzelnen Methoden ausgegangen werden, sondern von sieben Prinzipien guter Lehre, welche die Basis eines didaktischen Konzepts für die SML bilden. Im Kern zielen diese auf das reflexive Moment des Lern- und Lehrvorganges ab sowie auf das Sichtbarmachen dieses Vorgangs

Flexibilisierung von Studiengängen : Lernen im Zwischenraum von formellen und informellen Kontexten

Die School of Management and Law der ZHAW transformiert derzeit einen ganzen Studiengang in ein flexibilisiertes Lernformat. Die Studienform FLEX sieht vor, dass der Präsenzunterricht vor Ort um die Hälfte reduziert und durch dreiwöchige Online-Phasen ersetzt wird. Damit entsteht ein neuer Lernraum, der das formelle Lernen in informellen Kontexten stärkt. Der vorliegende Bericht beschreibt, wie die Transformation des Studienganges über alle 34 Module vollzogen und wie das Spannungsfeld zwischen informellen und formellen Kontext gestaltet wird

Dauerhaft digital : systematische Entwicklung und Implementation einer E-Learning-Strategie

E-Learning an Hochschulen hat längst den Status von Pilotprojekten hinter sich gelassen. Häufig jedoch fehlt eine Verstetigung auf institutioneller Ebene. In einem aufwendigen Prozess, der über mehrere Abstimmungszyklen alle Stakeholder involvierte, wurde an der School of Management and Law (SML) der ZHAW eine E-Learning-Strategie entwickelt und verabschiedet. Zentraler Entwicklungsbaustein war die Erstellung eines Morphologischen Kastens, der bei der Abstimmung über relevante Parameter und ihre Ausgestaltung zu einer kongruenten und systematischen Entscheidungsfindung beitrug. Für die Implementation der E-Learning-Strategie wurde das Analysemodell von Knoster herangezogen, um Schwierigkeiten und Widerstände zu antizipieren und geeignete Massnahmen abzuleiten

Leaf orientation as part of the leaf developmental program in the semi-deciduous shrub, Cistus albidus l.: Diurnal, positional, and photoprotective effects during winter

Mediterranean ecosystems harbor a very important part of Earth's biodiversity, and they are a conservation priority due to the effects of global change. Here, we examined the performance of the semi-deciduous shrub Cistus albidus under Mediterranean conditions during winter, including changes in leaf angle governed by diurnal, seasonal, and positional effects and their relationship with winter photoinhibition and photoprotection. We found marked diurnal variations in leaf angle during the day in autumn, which disappeared as the photoperiod shortened during winter due to a progressive decrease in the predawn leaf angle from November to January. During this period, auxin contents decreased, while those of melatonin increased, and the Fv/Fm ratio, chlorophyll, and tocopherol contents kept unaltered, thus indicating the absence of photoinhibitory damage. A marked decrease in the leaf angle toward the shoot apex occurred during winter, which was associated with slightly higher Fv/Fm ratios. An analysis of the inter-individual variability and sun orientation effects on leaf movements in a population growing in the Montserrat mountains revealed a very marked variability of 46.8% in the leaf angle, while Fv/Fm ratio showed a variation of 7.5% only. West orientation, which was associated with reduced leaf temperatures, but with no differences in the photosynthetic photon flux density, led to enhanced tocopherol contents, while leaf angle, Fv/Fm ratio, chlorophyll, auxin, and melatonin contents kept unaltered. It is concluded that (1) C. albidus has very effective and fine-regulated photoprotection mechanisms, including an adequate orientation of decussate leaves as part of the developmental program, (2) leaf angle is modulated on a diurnal and seasonal basis, thus contributing to prevent photoinhibition as a first line of defense, and (3) enhanced tocopherol contents help withstand combined high light with low temperature stress in C. albidus growing at high elevation

Interactions Between sucrose and jasmonate signalling in the response to cold stress

Background: Jasmonates play an important role in plant stress and defence responses and are also involved in the regulation of anthocyanin synthesis in response to sucrose availability. Here we explore the signalling interactions between sucrose and jasmonates in response to cold stress in Arabidopsis. Results: Sucrose and cold treatments increased anthocyanin content additively. Comprehensive profiling of phytohormone contents demonstrated that jasmonates, salicylic acid and abscisic acid contents increased in response to sucrose treatment in plants grown on agar, but remained considerably lower than in plants grown in compost. The gibberellin GA3 accumulated in response to sucrose treatment but only at warm temperature. The role of jasmonate signalling was explored using the jasmonate response mutants jar1-1 and coi1-16. While the jar1-1 mutant lacked jasmonate-isoleucine and jasmonate-leucine, it accumulated 12-oxo-phytodienoic acid at low temperature on agar medium. Altered patterns of abscisic acid accumulation and higher sugar contents were found in the coi1-16 mutant when grown in compost. Both mutants were able to accumulate anthocyanin and to cold acclimate, but the jar-1-1 mutant showed a larger initial drop in whole-rosette photosystem II efficiency upon transfer to low temperature. Conclusions: Hormone contents are determined by interactions between temperature and sucrose supply. Some of these effects may be caused indirectly through senescence initiation in response to sucrose availability. During cold stress, the adjustments of hormone contents may compensate for impaired jasmonate signalling, enabling cold acclimation and anthocyanin accumulation in Arabidopsis jasmonate response mutants, e.g. through antagonistic interactions between gibberellin and jasmonate signalling

Besser, schlechter, ändert nichts? Eine Evaluation des papierlosen Studiums aus didaktischer Sicht

StudieBesser, schlechter, ändert nichts? Diese oder eine ähnliche Frage kommt zwangsläufig auf, wenn im Unterricht Innovationen, seien sie didaktischer oder technologischer Art, eingeführt werden. Das Institut für Biotechnologie am Departement Life Sciences und Facility Management der Zürcher Hochschule für angewandte Wissenschaften (ZHAW) hat 2013 den Schritt gewagt und Studierende und Dozierende des zweiten Studienjahrs mit Tablets ausgestattet. Die vorliegende Studie untersucht diesen Pilotversuch aus didaktischer Perspektive. Dabei wurde eine phasenbezogene Betrachtungsweise gewählt, die den Einsatz von Tablets während der Präsenz-, der Selbststudiums-, der Prüfungsvorbereitungsphase und in der Prüfung unterscheidet und sowohl Dozierenden als auch Studierendenperspektive gleichermassen mit einbezieht. Über alle Lehr- und Lernphasen hinweg zeigen sich vielfältigste Lehr- und Lernpraktiken bei der Nutzung von Tablets, die alle zu einer sehr positiven Bewertung des Einsatzes führen. Die tatsächliche Stärke des Tablets liegt in der Vielfalt der Nutzungsmöglichkeiten, die sehr individuelle und sogar gegensätzliche Lernstile unterstützt. Insgesamt zeigt sich, dass gängige Vorurteile gegen die Nutzung von Tablets, wie beispielsweise ein erschwertes Lese- und Orientierungsverhalten im Text, nicht haltbar sind. Es muss als sehr positiv für den Tableteinsatz gewertet werden, dass das Lehren und das Lernen mit diesen Geräten so gut funktioniert, das Projekt durch die Teilnehmenden so positiv bewertet wird, obwohl keine didaktische Anpassungen am Unterricht vorgenommen worden sind. Natürlich gibt es auch Schwierigkeiten und Unstimmigkeiten, es zeigt sich aber, dass eine schrittweise Einführung und Umstellung ein praktikabler Weg hin zu einem Papierlosen Studium sind

The decapping activator Edc3 and the Q/N-rich domain of Lsm4 function together to enhance mRNA stability and alter mRNA decay pathway dependence in Saccharomyces cerevisiae

The rate and regulation of mRNA decay are major elements in the proper control of gene expression. Edc3 and Lsm4 are two decapping activator proteins that have previously been shown to function in the assembly of RNA granules termed P bodies. Here, we show that deletion of edc3, when combined with a removal of the glutamine/asparagine rich region of Lsm4 (edc3Δ lsm4ΔC) reduces mRNA stability and alters pathways of mRNA degradation. Multiple tested mRNAs exhibited reduced stability in the edc3Δ lsm4ΔC mutant. The destabilization was linked to an increased dependence on Ccr4-mediated deadenylation and mRNA decapping. Unlike characterized mutations in decapping factors that either are neutral or are able to stabilize mRNA, the combined edc3Δ lsm4ΔC mutant reduced mRNA stability. We characterized the growth and activity of the major mRNA decay systems and translation in double mutant and wild-type yeast. In the edc3Δ lsm4ΔC mutant, we observed alterations in the levels of specific mRNA decay factors as well as nuclear accumulation of the catalytic subunit of the decapping enzyme Dcp2. Hence, we suggest that the effects on mRNA stability in the edc3Δ lsm4ΔC mutant may originate from mRNA decay protein abundance or changes in mRNPs, or alternatively may imply a role for P bodies in mRNA stabilization

Development of a Method for Decision Support on Participation in Capacity Sharing for Manufacturing SMEs

A volatile, non-transparent market environment leads to fluctuations in the load on production capacities in the manufacturing sector, which are reflected within production in the over- or underutilization of machines and persons. Small and midsized enterprises (SMEs) are expecting increasing volatility, which is accompanied by an increase in the frequency of market and economic cycles. For SMEs it is difficult to cope with these fluctuations. Capacity sharing platforms can be a solution for this challenge. Platforms are available in different forms, but not used by companies often, because of prevailing scepticism in different fields. Therefore, a methodology will be developed to provide a decision support for or against platform usage. Additionally, the platform type choice will be supported, and the changes of logistic and economic indicators will be considered. With this information companies can make a qualitative decision, and the existing inhibitions can be alleviated