Abstract
When challenged with the fungus Alternaria alternata Japanese pear pathotype, the Arabidopsis plants produced no lesion. The plants did not produce both reactive oxygen species and HR cell death after challenge with A. alternata, although they denoted the resistance to A. alternata. The spore germination was observed microscopically at the surfaces of Arabidopsis plants and the penetration attempts were found at the cell walls. However, the infection hyphae were not seen in the cytoplasm of epidermal cells. In Arabidopsis plants infected with A. alternata, papillae were formed at the sites of attempted fungal penetration. On the other hand, changes in the expression patterns of ca.7000 genes were examined by cDNA microarray analysis in Arabidopsis plants after inoculation with A. alternata. In the results, the abundance of 128 mRNAs was increased, whereas that of 86 mRNAs was reduced. Physiological, molecular and genetic characterization of several genes is in progress.
