XVI International Botanical Congess

It is presumed that a large part of mutations of the Japanese morning glory were induced by Tpn transposons, an En/Spm type since all unstable alleles cloned had Tpns. Using 3'-terminal region, 200 clones containing both ends of Tpn transposons were screened from a genomic DNA library. The copy number of Tpn was estimated between 500 and 1000 copies per haploid genome. Sequencing analysis showed that these clones have very similar 500 bp regions in both ends. These transposable elements were classified into more than 30 types based on restriction maps of the internal regions. Surprisingly the internal sequences were derived from different host genes. A phylogenetic analysis showed that these Tpns often exchanged their terminal sequences with other types. These results suggest that Tpn family affected evolution of host genome.