Plant & Animal Genome VI Conference

P41

DIVERSIFICATION OF A RESTRICTION DNA FRAGMENTS IN SELECTED RICE CULTIVAR GENOMES

Molecular Biology Laboratory, Botany Department, University of Calcutta Calcutta-700019, India

We have reported the sequence of a PstI rice (IR36) genomic DNA clone (RG104) in the EMBL databank as putative transposon (OSY07612) - read from automatic and manual sequencing. Its purative transposon nature is reported (Nucleus v. 39, 1996). To note its sequence divergence within available indica rice cultivars, two approaches were made: (1) RFLP studies using the entire 820 bp fragment as the probe and (2) RAPD studies using oligos (10-12 bases) designed from the clone. In total 17 oligos were designed. Results indicate the RG104 clone has AT and TAA preferences in short stretches. It lighted up cytosine methylation in IR36 genome, i.e. it might contain mutational "hot spots". Dendogram constructed on DNA polymorphism shows similarity to the dendogram on isoenzyme bands, and out of 1500 DNA bands about 1200 are polymorphic. Some oligos showed preferential amplification even when bands are at the same positions. RFLP data suggests that this DNA fragment could be used as a successful RFLP probe. We grately acknowledge the technical help of Dr. A. Mitra and his group at the University of Nebraska and of computation help of the DIC of the Bose Institute (Calcutta). Material help of Chinsura Rice Research Centre is also acknowledged.