Microarray-based detection of defence-related genes in Norway spruce towards Heterobasidion annosum

The fungal pathogen Heterobasidion annosum causes severe damage in forests by causing root and stem rot in Norway spruce.The premise for this work is that the level of natural resistance has a genetic basis and is reflected in the type and/or level of transcripts being expressed by the plant. Genetically identical clonal plants developed using somatic embryogenesis and rooted cuttings will be used. The transcription pattern in lines of spruce clones will be analyzed by array technology. Probes corresponding to the number and level of transcripts will be generated by RT-PCR, labeled and then hybridized to a large number of spruce cDNA clones to assay the difference between and within the clonal lines. Differences both in the constitutive expression and induced responses to infection will be examined. This data will be compared with relative disease resistance of different clones, obtained from pathogenicity tests, to detect RNA markers that correlate with disease resistance. Information generated in this project could be of scientific, practical and economic importance used in selection and breeding of resistant tree varieties. Since decay caused by Heterobasidion annosum is the major growth and quality-limiting factor in growing Norway spruce, this knowledge could have significant economic impacts.