Identification of Differentially Expressed Genes in Susceptible and Resistant Responses of Chinese Cabbage to Plasmodiophora brassicae

Di€erential gene expression in susceptible and resistant responses of Chinese cabbage to Plasmodiophora brass- icae was examined by di€erential screening of randomly ampli®ed cDNAs. Three cDNA fragments (H6±2, H8, and Y4) hybridizing to di€erentially expressed mRNAs in RNA gel blot analysis were sequenced and subjected to database homology searches. H6±2 cDNA, detecting inhibited expression of the corresponding gene in the susceptible response, revealed signi®cant homology to the chloroplast 16S rRNA gene. H8 cDNA, hybridizing to an extra mRNA band in the susceptible response along with a band observed in common among suscept- ible, resistant and control responses had signi®cant homology with an Arabidopsis homeobox gene Athb-8. Southern blot analysis showed that sequences hybrid- izing to H8 cDNA were contained in the genomic DNA of both Chinese cabbage and P. brassicae. Y4 cDNA, detecting enhanced expression of the corresponding gene in the resistant response, shared homology with an A. thaliana transcribed sequence with an unknown function.