Research themes

Publications

Teaching activities

Cooperations:

Max-Planck Institute for 
Limnology (Plön), 
Department of Tropical 
Ecology

Max-Planck Institute for 
Chemistry (Mainz), 
Department of 
Biogeochemistry

University Bonn, 
Ecophysiology of 
Plants - Institute of Botany

Instituto National de 
Pesquisas da Amazônia 
(INPA) at Manaus (Brasil)

Bundesanstalt für 
Züchtungsforschung an 
Kulturpflanzen, 
Institut für 
Zierpflanzenforschung

Humboldt-Universität Berlin,
AG Angewandte Botanik

The central aim of our work is to search for the mechanistic basis of adaptive processes in terrestrial plants to adverse soil conditions and to understand the regulation of acclimatory processes in response to environmental changes. Research is focused on the regulation of iron homeostasis, stimulus-induced epidermal cell differentiation, and on adaptations of trees from the Central Amazon floodplain to flooding stress. 
Iron levels in plants are controlled by various parallel but, at least partly, separate pathways. The role of inter-organ signaling in coordinating the responses of root cells (expression and subcellular localization of membrane bound enzymes, and structur changes such as the formation of transfer cells, root hairs and cluster roots) to the plants`s demand is investigated by means of immunocytochemical labeling and in situ hybridization in hormone-related mutants and in mutants with de-regulated Fe uptake.
The role of putative signal transmitters in the induction of the various responses to Fe deficiency is also studied. A further point of interest is the identification of iron responsive elements (IREs) and iron responsive element binding proteins (IRPs). Root epidermal cells can differentiate into hair or non-hair cells, often in a well-defined, predictable pattern. This pattern is affected by various abiotic stimuli, such as sub-optimal supply of the essential nutrients iron and phosphate. We are investigating the signal pathways leading to alterations in epidermal patterning by screening mutants in Arabidopsis that are unable to induce the phenotypes characteristic of phosphate-deficient plants. The isolation of genes involved in the translation of environmental signals to changes in epidermal cell specification in the aging primary root should help to understand the molecular basis underlying the adaptation of plants to adverse soil conditions. 
Low oxygen levels in the rhizosphere, caused by waterlogging or complete submergence, is a serious environmental stress that affects plant productivity and distribution in natural habitats. The Central Amazon floodplain is one of the largest inundation areas in the world. Plants of the inundation forests are subjected to flooding periods for up to ten months with an average amplitude of about ten meters. The monomodal flood pulse causes an annual change between relatively dry and oxic conditions and prolonged flooding, causing drastic changes in the bioavailability of nutrients, oxygen levels, and concentration of phytotoxins. By using morphological, physiological, biochemical, and molecular approaches, we are trying to add insights in the adaptations that have evolved in flood-tolerant trees to overcome the long flooding periods.