Global expression of defence-related genes in Populus and transfer of knowledge to Norway spruce

Due to the great economic losses caused by the root and butt-rot pathogen Heterobasidion annosum, developments of efficient control measures are warranted. Considerable clonal variation has been recorded for Norway spruce in resistance towards H. annosum, but the defence mechanisms contributing to host resistance remain poorly understood. The recent genome sequencing of Populus has made the genus a model to facilitate tree genetics. Genome-wide transcript profiling of Populus tremula upon pathogen attack will now be used, and homologues of Norway spruce genes to defence genes up-regulated in Populus will be identified. Based on the identified homologues, real-time PCR will be employed to screen the defence responses of Norway spruce clones showing differe ntial resistance toward H. annosum. This will enable identification of the components and marker genes of host defence in Norway spruce, knowledge that can be used in a breeding program targeted to resistance of Norway spruce toward Heterobasidion.