Expression of Heterobasidion annosum genes during its saprophytic and parasitic growth in Norway spruce

The wood decay fungus Heterobasidion annosum is by far the most important pathogen of Norway spruce in the Nordic countries. Despite of the considerable economic impacts of the disease, the genome of H. annosum is presently poorly characterized and subseq uently very little is known about its pathogenicity factors or factors contributing to the efficient colonization of wood. Knowledge on the strategies employed by the pathogen forms an important basis for understanding of the host defense responses and wh en developing more resistant tree genotypes by breeding. EST sequencing offers a low cost strategy to identify H. annosum genes expressed at the different stages of wood colonization. In the now planned project, cDNA libraries will be constructed from cru cial stages regarding colonization of Norway spruce by S type H. annosum. Array and real-time PCR technology will be subsequently employed to monitor the expression of H. annosum genes during different stages of Norway spruce colonization.