As primary producers of organic matter, plants constitute an attractive habitat for micro-organisms. Different types of interactions are described like killing of infected cells by necrotrophic fungi, exploitation of resources from living host cells by biotrophic pathogens, and symbiotic interactions which benefit both sides. The life style of the soil-borne, vascular fungal pathogen V. longisporum (VL) constitutes still another form of interaction. Here, the fungus persists for a long time in the xylem of its host without causing severe damage. In general, stunting and early senescence are observed during this stage. Conidiospores, which are transported with the transpiration stream to the shoot, ensure eventual colonization of the whole plant. VL infections on oilseed rape become apparent only during the ripening period, and breaks out of the vessels into the xylem parenchyma, stem pith and stem parenchyma to produce microslerotia. VL infections represent a serious threat to oilseed rape which has evolved to the most important oil crop in the temperate climates. Due to the booming biofuel markets, the importance is likely to expand in the future. In the absence of effective fungicides or resistant cultivars, the understanding of the Brassicaceae-VL interaction might lead to innovative strategies to combat the disease.

The Verticillium research unit, which consists of 9 partners of the Georg August University Göttingen, has chosen VL as a common experimental system to address the question how plants can sense and react to foreign organisms in the xylem and how micro-organisms adapt to the growth conditions inside the plant. The interaction is investigated using the different expertise of laboratories working in the fields of biochemistry, cell biology, molecular genetics, plant physiology, plant pathology and microbiology.

The common research objectives of the Verticillium research unit are:

• Identification of signals of plant and fungal origin that shape the interaction.

• Elucidation of the response of the plant to the fungus, including signal transduction processes and functional analysis of the elicited responses.

• Elucidation of the response of the fungus to the plant, including signal transduction processes as well as functional analysis of the elicited response for its pathogenicity.

PhD students: Hella Tappe (2004-2008), Anjali Ralhan (since 2008)

Publications: Tappe et al. 2008 (submitted)