Künstliche Inokulation von Gerstenpflanzen mit dem Flugbranderreger (Ustilago nuda) und Infektionsverlauf auf dem Fruchtknoten

ZusammenfassungZiel der Arbeit war die Prüfung künstlicher Inokulationsverfahren von Gerstenpflanzen mit dem Flugbranderreger (Ustilago nuda) und das Erlangen von Erkenntnissen zum genauen Infektionsverlauf auf dem Fruchtknoten. Diese Versuche sollten die Basis sein, um zukünftig hoch befallenes Saatgut in ausreichender Menge herstellen zu können, was für Folgeexperimente von großer Wichtigkeit wäre. Hierzu wurden drei Inokulationsmethoden – Inokulation mit der Spritze, Vakuuminfiltration und Besprühen mit Sporensuspension – hinsichtlich der erhaltenen Befallsraten und ihrem Einfluss auf die Keimfähigkeit miteinander verglichen. Weiterhin wurde untersucht, ob die Position des inokulierten Blütchens an der Ähre einen Einfluss auf den späteren Befall des daraus hervorgehenden Korns hat. Zu diesem Zweck wurden die Ähren zunächst per Spritze inokuliert und anschließend beim Ernten in jeweils drei Teile zerlegt und gesondert über einen Embryotest ausgewertet. Als aussichtsreichste Inokulationsmethode kristallisierte sich die Inokulation mit der Spritze heraus. Ein Einfluss der Ährenregion auf den späteren Befall konnte nicht nachgewiesen werden. Des Weiteren wurden mikroskopische Untersuchungen durchgeführt, die zu einem besseren Verständnis des Infektionsverlaufes auf dem Fruchtknoten führen sollten. Hierfür wurde ein lactophenolbasierendes Autoklavieranfärbeverfahren verwendet. Es konnte gezeigt werden, dass eine Infektion des Fruchtknotens nicht zwingend über die Narbe stattfinden muss, und dass der Pilz bei einer erfolgreichen Infektion die obersten Zellschichten der Fruchtknotenwand intrazellulär mit einer Infektionshyphe penetriert.Stichwörter: Brandkrankheiten, Flugbrandbefall, BlüteninokulationAbstract The aim of this study was the examination of artificial inoculation techniques of barley with the pathogen (Ustilago nuda) and to obtain detailed new findings on the mode of infection on the ovary. These tests were designed to be the base to produce a sufficient amount of highly infected seeds, which would be of great importance for further experiments. Three inoculation techniques - by injection, vacuum infiltration or spraying with spore suspension - were compared with respect to the resulting infection rates and their influence on the germination rate. Moreover, it was evaluated, if the position of the inoculated floret on the ear has any influence on subsequent infection of the developing grain. Therefore the ears were inoculated by injection and, after harvesting, divided in three parts and separately evaluated with an embryo test. The most promising inoculation technique turned out to be inoculation by injection. An influence of the ear area on subsequent infection was not detected. In addition, microscopic analyses were carried out, which should provide a better understanding of the mode of infection on the ovary. A lactophenolbased autoclave staining technique was applied. The analysis showed that an infection of the ovary does not necessarily originate from the stigma, and that in case of an effective infection the fungus penetrates the uppermost cell layers of the ovary intracellularly with an infection hypha.Keywords: smuts, loose smut, flower inoculatio

Covid-19 and the onlineification of research: kick-starting a dialogue on Responsible online Research and Innovation (RoRI)

The COVID-19 crisis opened up discussions on using online tools and platforms for academic work, e.g. for research (management) events that were originally designed as face-to-face interactions. As social scientists working in the domain of responsible research and innovation (RRI), we draft this paper to open up a dialogue on Responsible online Research and Innovation (RoRI), and deliberate particular socioethical opportunities and challenges of the onlineification in collaborative theoretical and empirical research. An RRI-inspired ‘going online’ approach would mean, we suggest, trying to make academic events and research activities more inclusive, researchers’ attitude to their work more reflective and suggest processes that are more responsive to societal needs and ethical concerns. For such systematic reflection, we suggest using the RRI-heuristic provided by Owen et al., and applying the dimensions of ‘Anticipation, Inclusion, Reflection and Responsiveness’ (AIRR) in order to identify and reflect on the dilemmas involved in ‘going online’ in one’s research

Metabolic state alters economic decision making under risk in humans

Background: Animals' attitudes to risk are profoundly influenced by metabolic state (hunger and baseline energy stores). Specifically, animals often express a preference for risky (more variable) food sources when below a metabolic reference point (hungry), and safe (less variable) food sources when sated. Circulating hormones report the status of energy reserves and acute nutrient intake to widespread targets in the central nervous system that regulate feeding behaviour, including brain regions strongly implicated in risk and reward based decision-making in humans. Despite this, physiological influences per se have not been considered previously to influence economic decisions in humans. We hypothesised that baseline metabolic reserves and alterations in metabolic state would systematically modulate decision-making and financial risk-taking in humans. Methodology/Principal Findings: We used a controlled feeding manipulation and assayed decision-making preferences across different metabolic states following a meal. To elicit risk-preference, we presented a sequence of 200 paired lotteries, subjects' task being to select their preferred option from each pair. We also measured prandial suppression of circulating acyl-ghrelin (a centrally-acting orexigenic hormone signalling acute nutrient intake), and circulating leptin levels (providing an assay of energy reserves). We show both immediate and delayed effects on risky decision-making following a meal, and that these changes correlate with an individual's baseline leptin and changes in acyl-ghrelin levels respectively. Conclusions/Significance: We show that human risk preferences are exquisitely sensitive to current metabolic state, in a direction consistent with ecological models of feeding behaviour but not predicted by normative economic theory. These substantive effects of state changes on economic decisions perhaps reflect shared evolutionarily conserved neurobiological mechanisms. We suggest that this sensitivity in human risk-preference to current metabolic state has significant implications for both real-world economic transactions and for aberrant decision-making in eating disorders and obesity

Perennial snow and ice variations (2000–2008) in the Arctic circumpolar land area from satellite observations

Perennial snow and ice (PSI) extent is an important parameter of mountain environments with regard to its involvement in the hydrological cycle and the surface energy budget. We investigated interannual variations of PSI in nine mountain regions of interest (ROI) between 2000 and 2008. For that purpose, a novel MODIS data set processed at the Canada Centre for Remote Sensing at 250 m spatial resolution was utilized. The extent of PSI exhibited significant interannual variations, with coefficients of variation ranging from 5% to 81% depending on the ROI. A strong negative relationship was found between PSI and positive degree‐days (threshold 0°C) during the summer months in most ROIs, with linear correlation coefficients (r) being as low as r = −0.90. In the European Alps and Scandinavia, PSI extent was significantly correlated with annual net glacier mass balances, with r = 0.91 and r = 0.85, respectively, suggesting that MODIS‐derived PSI extent may be used as an indicator of net glacier mass balances. Validation of PSI extent in two land surface classifications for the years 2000 and 2005, GLC‐2000 and Globcover, revealed significant discrepancies of up to 129% for both classifications. With regard to the importance of such classifications for land surface parameterizations in climate and land surface process models, this is a potential source of error to be investigated in future studies. The results presented here provide an interesting insight into variations of PSI in several ROIs and are instrumental for our understanding of sensitive mountain regions in the context of global climate change assessment

A new spatially scanning 2.7 µm laser hygrometer and new small-scale wind tunnel for direct analysis of the H2_{2}O boundary layer structure at single plant leaves

A new spatially scanning TDLAS in situ hygrometer based on a 2.7-µm DFB diode laser was constructed and used to analyse the water vapour concentration boundary layer structure at the surface of a single plant leaf. Using an absorption length of only 5.4 cm, the TDLAS hygrometer permits a H2O vapour concentration resolution of 31 ppmv. This corresponds to a normalized precision of 1.7 ppm m. In order to preserve and control the H2O boundary layer on an individual leaf and to study the boundary layer dependence on the wind speed to which the leaf might be exposed in nature, we also constructed a new, application specific, small-scale, wind tunnel for individual plant leaves. The rectangular, closed-loop tunnel has overall dimensions of 1.2 × 0.6 m and a measurement chamber dimension of 40 × 54 mm (H × W). It allows to generate a laminar flow with a precisely controlled wind speed at the plant leaf surface. Combining honeycombs and a miniaturized compression orifice, we could generate and control stable wind speeds from 0.1 to 0.9 m/s, and a highly laminar and homogeneous flow with an excellent relative spatial homogeneity of 0.969 ± 0.03. Combining the spectrometer and the wind tunnel, we analysed (for the first time) non-invasively the wind speed-dependent vertical structure of the H2O vapour distribution within the boundary layer of a single plant leaf. Using our time-lag-free data acquisition procedure for phase locked signal averaging, we achieved a temporal resolution of 0.2 s for an individual spatial point, while a complete vertical spatial scan at a spatial resolution of 0.18 mm took 77 s. The boundary layer thickness was found to decrease from 6.7 to 3.6 mm at increasing wind speeds of 0.1–0.9 m/s. According to our knowledge, this is the first experimental quantification of wind speed-dependent H2O vapour boundary layer concentration profiles of single plant leaves

Absolute, high resolution water transpiration rate measurements on single plant laaves via tunable diode laser absorption spectroscopy (TDLAS) at 1.37 µm

A new sampling-free and calibration-free multi-channel hygrometer using near infrared (NIR) tunable diode laser absorption spectroscopy (TDLAS) at 1.37 mu m was developed and used to determine absolute transpiration rates of single plant leafs. Four 8 x 6 x 4 cm(3), fiber-coupled absorption cells are used to simultaneously measure absolute water vapor concentrations with an absolute accuracy of about 5% and a temporal resolution of about 2 s. Two chambers (BOTTOM, TOP) are directly attached to the leaf surface, while two chambers (IN, OUT) analyze the purge gas supplied to the plant leaf and the total outflow of the leaf chambers. The BOTTOM-TOP comparison provided a direct, leaf-side resolved ratio of stomatal conductance and-by taking into account the purge gas flow and the leaf area exposed-leaf side resolved water transpiration rates. The OUT-IN-difference yielded the total leaf transpiration rate with 2 mu mol/m(2)/s resolution. The new multi-point hygrometer was validated by monitoring of the transpiration dynamics of a plant of the species Epipremnum pinnatum (L.) Engl. during diurnal variation of the leaf irradiation. During these experiments the differential H2O concentration resolution between two chambers was determined to be better than 3 ppm at Delta t = 2s (i.e. better than 711 ppb m Hz(1/2)). This performance was verified by an Allan analysis over a 30 min time period using CH4 as a surrogate absorber and yielded an average optimum optical resolution of 4.9 x 10(-6) for 83 s measurement time, i.e. a CH4 resolution of 892 ppb, which corresponds to the optical resolution needed for a water sensitivity of 454 ppb m Hz(1/2)