The hypothesis that the dark septate root endophyte Phialocephala fortinii provides biological control of Phytophthora diseases to trees is tested under two temperature regimes. Phytophthora spp. are very aggressive plant pathogens affecting also woody plants in the natural environment. Studies on biological control of Phytophthora diseases are scarce, but antagonistic effects of endophytic fungi have been demonstrated in a few cases. In temperate and boreal forests, conifers are much less susceptible to Phytophthora diseases than deciduous broadleaf trees, whereas their roots are very frequently colonized by dark septate endophytes (DSE) with Phialocephala fortinii s.l., a supposedly asexual ascomycete, being the dominant component. This fungus also colonizes hardwoods, but to a lesser degree. Recent population genetic studies showed that P. fortinii s.l. consists of at least 15 reproductively isolated cryptic species (CSP). We hypothesise that P. fortinii s.l. may protect its host from Phytophthora disease depending on CSP and environmental conditions. A model system will be developed and applied to test this hypothesis using Norway spruce (Picea abies), beech (Fagus sylvatica) and Phytophthora citricola. The experimental program will be multidisciplinary in approach and include molecular, mycological, phytopathological (infection experiments, epifluorescence microscopy) and statistical methods.
The magnetosphere of a planet is controlled by a number of factors such as the intrinsic magnetic field, the atmosphere and ionosphere, and the solar wind. Different combinations of these control factors are at work at the terrestrial planets Mercury, Venus, Earth, and Mars, hence they form a very suitable set for quantitative comparative studies. A significant intrinsic dipolar magnetic field is present only on Earth and on Mercury. However, the configuration at Mercury differs considerably from that at Earth because Mercury does not support an atmosphere and ionosphere, the dipolar field is much weaker, the solar wind denser, and the interplanetary magnetic field stronger. Both Mars and Venus have atmospheres but lack a global planetary magnetic field, with regional crustal magnetization being present on Mars. This proposal aims at investigating and comparing electrical current systems in the space environments of terrestrial planets using magnetic vector data collected by orbiting spacecraft such as Venus Express, Mars Global Surveyor, CHAMP (Earth), and MESSENGER (Mercury). We propose to construct data-driven and physically meaningful representations that reveal and quantify the influence of various control factors. To achieve this, we will tailor Empirical Orthogonal Function (EOF) analysis and other multivariate methods to the specifics of planetary magnetic field observations. In contrast to representations that build on predefined functions like spherical harmonics, basis functions in the EOF approach are derived directly from the data. EOFs are designed to extract dominant coherent variations for further interpretation in terms of known physical phenomena, and then, in a regression step, for modeling using suitable control variables. The EOF methodology thus allows quantifying the relative importance of control factors for each planet individually, and thus contributes to the solution of topical science questions. The resulting empirical models will facilitate comparative studies of current systems at the terrestrial planets.
The goal of this project is to capture and analyse fluctuations of the fresh water in the western Nordic Seas and to understand the related processes. The East Greenland Current in the Nordic Seas constitutes an important conduit for fresh water exiting the Arctic Ocean towards the North Atlantic. The Arctic Ocean receives huge amounts of fresh water by continental runoff and by import from the Pacific Ocean. Within the Arctic Ocean fresh water is concentrated at the surface through sea ice formation. The East Greenland Current carries this fresh water in variable fractions as sea ice and in liquid form; part of it enters the central Nordic Seas, via branching of the current and through eddies. It controls the intensity of deep water formation and dilutes the water masses which result from convection. The last decades showed significant changes of the fresh water yield and distribution in the Nordic Seas and such anomalies were found to circulate through the North Atlantic. In this project the fresh water inventory, its spatial distribution and its pathways between the East Greenland Current and the interior Greenland and Icelandic seas shall be captured by autonomous glider missions. The new measurements and existing data will, in combination with the modeling work of the research group, serve as basis for understanding the causes of the fresh water variability and their consequences for the North Atlantic circulation and deep water formation.
Background and Objectives: The project area is located in the Ashanti Region of Ghana / West Africa in the transition zone of the moist semideciduous forest and tropical savannah zone. Main land use in this region is subsistence agriculture with large fallow areas. As an alternative land-use, forest plantations are under development by the Ghanaian wood processing company DuPaul Wood Treatment Ltd. Labourers from the surrounding villages are employed as permanent or casual plantation workers. Within three forest plantation projects of approximately 6,000 ha, DuPaul offers an area of 164 ha (referred to as Papasi Plantation) - which is mainly planted with Teak (Tectona grandis) - for research purposes. In return, the company expects consultations to improve the management for sustainable timber and pole production with exotic and native tree species. Results: In a first research approach, the Papasi Plantation was assessed in terms of vegetation classification, timber resources (in qualitative and quantitative terms) and soil and site conditions. A permanent sampling plot system was established to enable long-term monitoring of stand dynamics including observation of stand response to silvicultural treatments. Site conditions are ideally suited for Teak and some stands show exceptionally good growth performances. However, poor weed management and a lack of fire control and silvicultural management led to high mortality and poor growth performance of some stands, resulting in relative low overall growth averages. In a second step, a social baseline study was carried out in the surrounding villages and identified landowner conflicts between some villagers and DuPaul, which could be one reason for the fire damages. However, the study also revealed a general interest for collaboration in agroforestry on DuPaul land on both sides. Thirdly, a silvicultural management concept was elaborated and an improved integration of the rural population into DuPaul's forest plantation projects is already initiated. If landowner conflicts can be solved, the development of forest plantations can contribute significantly to the economic income of rural households while environmental benefits provide long-term opportunities for sustainable development of the region. Funding: GTZ supported PPP-Measure, Foundation
The nature of the microbial communities inhabiting the deeper soil horizons is largely unknown. It is also not clear why subsurface microorganisms do not make faster use of organic compounds under field conditions. The answer could be provided by a reciprocal soil transfer experiment studying the response of transferred soils to fluctuations in microclimate, organic inputs, and soil biota. The subproject P9 will be responsible for the establishment of reciprocal transfer experiments offering a strong link between subgroups interested in organic matter quality, transport of organic substances, as well as functions of the soil microbial community. A single, high molecular weight substrate (13C labelled cellulose) will be applied at two different levels in the pre-experiment to understand the dose-dependent reaction of soil microorganisms in transferred surface and sub-soils. Uniformly 13C labelled beech roots - representing complex substrates - will be used for the main reciprocal soil transfer experiment. We hypothesize that transferring soil cores between subsoil and surface soil as well as addition of labelled cellulose or roots will allow us to evaluate the relative impact of surface/subsurface habitat conditions and resource availability on abundance, function, and diversity of the soil microbial community. The second objective of the subproject is to understand whether minerals buried within different soil compartments (topsoil vs. subsoil) in the field contribute to creation of hot spots of microbial abundance and activity within a period of two to five years. We hypothesize that soil microorganisms colonize organo-mineral complexes depending on their nutritional composition and substrate availability. The existence of micro-habitat specific microbial communities could be important for short term carbon storage (1 to 6 years). The third objective is to understand the biogeography and function of soil microorganisms in different subsoils. Parent material as well as mineral composition might control niche differentiation during soil development. Depending on size and interconnectedness of niches, colonization and survival of soil microbial communities might be different in soils derived from loess, sand, terra fusca, or sandstone. From the methodological point of view, our specific interest is to place community composition into context with soil microbial functions in subsoils. Our subgroup will be responsible for determining the abundance, diversity, und function of soil microorganisms (13C microbial biomass, 13C PLFA, enzyme activities, DNA extraction followed by quantitative PCR). Quantitative PCR will be used to estimate total abundances of bacteria, archaea and fungi as well as abundances of specific groups of bacteria at high taxonomic levels. We will apply taxa specific bacterial primers because classes or phyla might be differentiated into ecological categories on the basis of their life strategies.
Südchina, insbes. die Provinz Guandong, ist eines der am dichtesten besiedelten Gebiete der Erde. Positive Konsequenz dieser Ballung ist eine äußerst dynamische Wirtschaftsentwicklung, aber gerade diese von subtropischem Monsunklima geprägte Region ist auch immer wieder Ausgangspunkt für sich schnell und zunehmend global ausbreitende epidemische Krankheiten wie zuletzt SARS. Mit der globalen Erwärmung einhergehende Klimaveränderungen könnten sich für diese Region insbesondere durch Veränderungen der Häufigkeit und Intensität tropischer Wirbelstürme, aber auch Änderungen der Niederschlagsmenge- und Intensität bemerkbar machen. Im Gegensatz zu den schon recht umfangreichen Datensätzen aus der Südchinesischen See (SCS) gibt es bisher jedoch nur sehr wenige terrestrische Paläoklimaarchive aus der Region, die Klimaveränderungen während des Holozäns, des Spätglazials oder Glazials hochauflösend dokumentieren. Wir haben deshalb einen an der nördlichen Küste der SCS gelegenen Maarsee ausgewählt, um über die Analyse von Proxydaten aus Seesedimenten solche Paläo-Klimavariationen zu untersuchen. Aus dem Sediment des Huguang-Maarsees wurden mittels Usinger-Präzisionsstechtechnik von einem Floss aus insgesamt 7 Sedimentsequenzen gewonnen, von denen die tiefste bis 57 m unter den Seeboden reicht. Die zeitliche Einstufung der Profile wurde mit Hilfe von 17 Radiokohlenstoff-Datierungen vorgenommen und ergab ein extrapoliertes Maximalalter von ca. 78.000 Jahren. Ein breites Spektrum aus sedimentologischen, geochemischen, paläo- und gesteinsmagnetischen sowie palynologischen Methoden kam sodann zum Einsatz, um die Paläo-Umweltbedingungen, die natürlich immer das entsprechende Klima widerspiegeln, während dieses Zeitraumes zu rekonstruieren. Überraschenderweise ergab sich ein von vielen bekannten Klimaprofilen der Nordhemisphäre (insbes. des Atlantikraumes, aber auch mariner Kerne aus dem Indik und Südostasien) abweichendes Muster. Im Gegensatz zu dem bekannten Grundmuster eines vergleichsweise stabilen Klimas während des Holozäns und stärkerer Schwankungen während des letzten Glazials weisen die Daten aus dem Huguang-Maarsee für das letzte Glazial im Zeitraum zwischen 15.000 und 40.000 Jahren auf relativ stabile Umweltbedingungen hin. Die älteren Bereiche zwischen 40.000 und ca. 78.000 Jahren haben durch Eintrag von umgelagertem Torf eine eher lokale Komponente und sind somit für den regionalen und globalen Vergleich ungeeignet. Das Holozän hingegen zeichnet sich durch hohe Schwankungsamplituden vieler Proxydaten (Karbonatgehalt, magnetische Suszeptibilität, organischer Kohlenstoff, Trockendichte, gesteinsmagnetische Parameter, Redox-Verhältnisse) aus, die auf ein recht variables Klima hinweisen. Besonders interessant ist die Übergangsphase vom Glazial zum Holozän, die bei etwa 15.000 Jahren vor heute in etwa zeitgleich mit dem beobachteten stärksten Meeresspiegelanstieg der Südchinesischen See einsetzt und eine abrupte Intensitätszunahme des Sommermonsuns anzeigt
Unsere Motivation liegt in der Tatsache, dass die dynamische Verbindung zwischen dem marinen Oberflächenfilm (engl. sea-surface microlayer, SML) und der darunterliegenden oberflächennahen Wasserschicht über Konvektion zu heterogenen Eigenschaften der SML führt. Dies wiederum steuert das Ausmaß der bio-photochemischen Reaktionen und des Gasaustausches zwischen dem Ozean und der Atmosphäre. Die Konvektion wird durch Verdunstung angetrieben, die die SML abkühlt und es salzhaltiger macht. Infolgedessen wird die SML dichter, sinkt ab und wird durch das darunterliegende Wasser ersetzt. Die auftriebsgetriebene Konvektion wurde jedoch bei der Erforschung der SML und des Gasaustausches als dynamisches Bindeglied zwischen der Atmosphäre und dem Ozean vernachlässigt. Unser Hauptziel ist es, ein mechanistisches Verständnis der Dynamik zwischen der SML und der oberflächennahen Wasserschicht zu beschreiben. Ein mechanistisches Verständnis der Konvektion ist wichtig, da das Ausmaß der bio-photochemischen Reaktionen und Austauschprozessen von Spurengasen, Energie und Impuls letztlich durch Austauschprozesse zwischen der SML und der oberflächennahen Wasserschicht und schließlich mit tieferen Schichten bestimmt wird. Wir werden einen experimentellen Aufbau mit mehreren profilierenden Mikroelektroden und einem optischen Schlierensystem entwickeln, um die Konvektion unter verschiedenen externen Antrieben zu untersuchen. Wir werden den Effekt der horizontalen Strömung aufgrund von Gradienten der Oberflächenspannung (d.h. Marangoni-Effekt) untersuchen. Wir werden auch an dem gemeinsamen Mesokosmen-Experiment BASS teilnehmen, um den Einfluss biogener Tenside auf den konvektiven Transportmechanismus zwischen der SML und der oberflächennahen Wasserschicht zu untersuchen. Im gemeinsamen Feldexperiment BASS werden wir der Frage nachgehen, inwieweit Variationen der klein-skaligen Konvektion durch die Variabilität sub-mesoskaligen (1 km-10 km) und hydrodynamischen Prozessen nahe der Meeresoberfläche beeinflusst werden. Wir werden zwei Forschungskatamarane und eine Flotte von Treibbojen einsetzen, die mit Leitfähigkeits- und Temperatursensoren ausgestattet sind, um Dichteanomalien zwischen der SML und oberflächennahen Wasserschicht zu untersuchen. Wir werden externe ozeanische und atmosphärische Einflüsse beobachten, um die Dichteanomalien zu beschreiben. Schließlich werden wir die gewonnenen Erkenntnisse aus den Laborexperimenten, der Mesokosmos-Studie und der Feldstudie nutzen, um einen mathematischen Rahmen zur Beschreibung von Temperatur- und Salzgehaltsprofilen und deren Schwankungen unter dem Einfluss definierter ozeanischer und atmosphärischer Einflüsse zu entwickeln.
The basidiomycete Armillaria mellea s.l. is one of the most important root rot pathogens of forest trees and comprises several species. The aim of the project is to identify the taxa occurring inSwitzerland and to understand their ecological behaviour. Root, butt and stem rots caused by different fungi are important tree diseases responsible for significant economic losses. Armillaria spp. occur world-wide and are important components of many natural and managed forest ecosystems. Armillaria spp. are known saprothrophs as well as primary and secondary pathogens causing root and butt rot on a large number of woody plants, including forest and orchard trees as well as grape vine and ornamentals. The identification of several Armillaria species in Europe warrants research in the biology and ecology of the different species. We propose to study A. cepistipes for the following reasons. First, A. cepistipes is dominating the rhizomorph populations in most forest types in Switzerland. This widespread occurrence contrasts with the current knowledge about A. cepistipes, which is very limited. Second, because the pathogenicity of A. cepistipes is considered low this fungus has the potential for using as an antagonist to control stump colonising pathogenic fungi, such as A. ostoyae and Heterobasidion annosum. This project aims to provide a better understanding of the ecology of A. cepistipes in mountainous Norway spruce (Picea abies) forests. Special emphasis will be given to interactions of A. cepistipes with A. ostoyae, which is a very common facultative pathogen and which often co-occurs with A. cepistipes. The populations of A. cepistipes and A. ostoyae will be investigated in mountainous spruce forests were both species coexist. The fungi will be sampled from the soil, from stumps and dead wood, and from the root system of infected trees to determine the main niches occupied by the two species. Somatic incompatibility will be used to characterise the populations of each species. The knowledge of the spatial distribution of individual genets will allow us to gain insights into the mode of competition and the mode of spreading. Inoculation experiments will be used to determine the variation in virulence expression of A. cepistipes towards Norway spruce and to investigate its interactions with A. ostoyae.
We will compare the role of an RNA-binding protein in floral transition in Arabidopsis thaliana and Hordeum vulgare. The RNA-binding protein AtGRP7 promotes floral transition mainly by downregulating the floral repressor FLC via the autonomous pathway. Based on our observation that AtGRP7 affects the steady-state abundance of a suite of microRNA precursors, we will globally compare the small RNA component of the transcriptome during FTi regulation in wild type plants and AtGRP7 overexpressors by deep sequencing. This will extend the knowledge on small RNAs associated with floral transition and provide insights into the regulatory network downstream of this RNA-binding protein. Further, we will address the question how AtGRP7 orthologues function in crop species lacking FLC homologues. A barley line with highly elevated levels of the AtGRP7 orthologue HvGR-RBP1 shows accelerated FTi and preanthesis development when compared to a near-isogenic parent with very low expression of this gene. We will characterize in detail flowering of this line with respect to different photoperiods and its vernalization requirement. We will employ a TILLING approach to further delineate the function of HvGR-RBP1 in flowering. A candidate gene approach to identify downstream targets will provide insights into the signaling pathways through which HvGR-RBP1 influences FTi. This project contributes to the development of a functional cross-species network of FTi regulators, the major strategic aim of the SPP.
The detritusphere is an excellent model to study microbial-physicochemical interactions during degradation of the herbicide MCPA. Whereas during the first phase of SPP 1315 we focused on bacterial and fungal abundance at the soil litter interface and carbon flow between different compartments, the second phase will be devoted to elucidating complex regulation mechanisms of MCPA degradation in the detritusphere: (1) At the cellular level, co-substrate availability and laccase abundance might be important regulators, (2) at the community level, bacteria harbouring different classes of tfdA genes might control degradation of MCPA and (3) at the microhabitat level, interaction between MCPA degraders and organo-mineral surfaces as well as transport processes might be important regulators. The concept of hierarchical regulation of MCPA degradation will be included into the modelling of small-scale microbial growth, MCPA transport and MCPA degradation near the soil-litter interface.
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