The group studies the molecular mechanisms involved in plant tolerance to environmental parameters. Special focus is given to the regulation of the chloroplast antioxidant system, which protects plants against photooxidative damage. Presently, we work on four main projects:

Genetic approaches for isolation of signal transduction elements involved in redox regulation of nuclear gene expression in higher plants

For identification and characterization of genes involved in the expressional control of antioxidant enzymes several Arabidopsis mutants with low activation of the 2-Cys peroxiredoxin-A (2CPA) promoter were isolated from a chemically mutagenized reporter gene line, which expresses luciferase under control of the redox-regulated 2CPA promoter. The rimb-mutants (redox-imbalanced) were compared for gene expression regulation, metabolite patterns and stress responses.

Analysis of transcription factor functions in plant protection against photooxidative stress

During evolution of plants, transcription factos highly diverified. Related transcription factors may compete for the same binding sites or may have taken over distinct functions. We study stress regulated transcription factors for their function in plant acclimation. Special attention is given to apetala-2-related transcription factors, which are involved in plant responses to abiotic stresses, such as drought, heat and high light.

Screening for and chararacterization of cis-regulatory elements involved in sensing of photosynthetic signals

cDNA-Array experimentes demonstrated that thousands of nuclear encoded genes respond to photosynthetic signals. Using enhancer trapping techniques and reporter gene approaches we screen for cis-regulatory elements which are involved in sensing photosynthetically controlled signals. Subsequently, we analyse them and their trans-regulators in vivo and in vitro to study the nuclear transformation of chloroplast signals into gene expression regulation.

Natural variation and inter-specific comparison of intracellular signalling mechanisms

During plant evolution and species diversification, the signalling mechanisms of the heterotrophic and phototrophic compartments were challenged by functional gene translocation and adaptation. Comparison of today´s plants demonstrate species- and ecotype-specific modifications of the chloroplast-to-nucleus signalling and regulation mechanisms. In a series of distinct sub-projects, different evolutionary traits are compared and signalling pathways studied.

The function of chloroplasts in priming

Teh experience of a stress event modifies the response to future stress events. The process is cold "priming". In the first series of experiments, we demonstrated that a 24 h cold stimulus modifies chloroplast-to-nucleus ROS signalling still  5 days after the priming stress event, which regulatio of genes responding to the canonical cold signalling pathway was not affected. The nature of the stress memory, its regulation and its impact on stress tolerance are presently under investigation.