CHARACTERIZATION OF DNA-SEQUENCES CLONED FROM RESTING SPORES OF PLASMODIOPHORA-BRASSICAE

Forty-four clones containing P. brassicae genomic DNA fragments were i solated from a partial genomic library (pUC118) of the fungus. Eleven DNA fragments were arbitrarily selected from them and partially sequen ced. Southern blot analysis was performed using the 11 DNA fragments a s probes to estimate the copy number of these DNA fragments in the P. brassicae genome and to see if they hybridized also to genomic DNA of host plant (Chinese cabbage). Five of those (Nos 24, 48, 54, 57, and 1 08) were of single-copy and hybridized only to DNA bands of P. brassic ae. Two fragments (Nos 4 and 15) were found to contain repetitive sequ ence of P. brassicae. Three fragments (Nos 69, 73, and 82) hybridized to DNA bands of both host and P. brassicae while the size and the numb er of the bands were different between host and P. brassicae. Data bas e searches revealed that one of the single-copy fragments (No. 48) had high homology with yeast RNA polymerase II gene.