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

Colletotrichum graminicola is the causal agent of leaf anthracnose and stem rot in maize. In acompatible interaction, this hemibiotrophic fungus sequentially establishes a biotrophicfollowed by a necrotrophic interaction. Previous studies have shown that biotrophic andnecrotrophic 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 theproposed research is to determine iron acquisition pathways in the fungus required to establisha biotrophic interaction and to switch to necrotrophic development. On the side of the hostplant, we will characterize the iron nutritional status and iron binding forms that promotepathogen sensitivity or resistance. The combined methodological approach relies on thegeneration 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 mutantplants with different pools and availabilities of iron. Fungal infection assays will be monitoredby gene expression studies, analyses of Fe binding forms and microscopic studies on hyphalpenetration, Fe dislocalisation and the production of reactive oxygen species. This study isdesigned to uncover the importance of iron as a signal and virulence factor in the C.graminicola-maize pathosystem.