Teilprojekt 10

Iron as a determinant of virulence and resistance in the Colletotrichum graminicola – maize interaction

Holger B. Deising (MLU), Nicolaus von Wirén (IPK)

Colletotrichum graminicola is the causal agent of leaf anthracnose and stem rot in maize. In a compatible interaction, this hemibiotrophic fungus sequentially establishes a biotrophic followed by a necrotrophic interaction. Previous studies have shown that biotrophic and necrotrophic growth depend on different iron acquisition strategies by the fungus, however, their relation to local iron availabilities in the plant tissue remain unclear. The aim of the proposed research is to determine iron acquisition pathways in the fungus required to establish a biotrophic interaction and to switch to necrotrophic development. On the side of the host plant, we will characterize the iron nutritional status and iron binding forms that promote pathogen sensitivity or resistance. The combined methodological approach relies on the generation of multiple C. graminicola mutants defective in several components of Fe(III) reduction or siderophore-based Fe acquisition and on the use of maize wildtype and mutant plants with different pools and availabilities of iron. Fungal infection assays will be monitored by gene expression studies, analyses of Fe binding forms and microscopic studies on hyphal penetration, Fe dislocalisation and the production of reactive oxygen species. This study is designed to uncover the importance of iron as a signal and virulence factor in the C. graminicola-maize pathosystem.

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