SYSTEMATIC ANALYSIS OF RICE GENES DISRUPTED BY INSERTION OF THE ENDOGENOUS RETROTRANSPOSON TOS17

¹ Institute of the Society for Techno-innovation of Agriculture, Forestry and Fisheries, Tsukuba, Ibaraki 305-0854, Japan

² National Institute of Agrobiological Resources, Tsukuba, Ibaraki 305-8602, Japan

A rice retrotransposon, Tos17, shows transposition induced by tissue culture; a low number of original copies (1-4) in the genome; a high frequency of transposition, resulting in 5-30 transposed copies; and random transposition throughout the genome. Thus Tos17 could be used for insertional mutagenesis, as a tool for functional analysis of rice genes. To screen mutant lines used for functional analysis of genes, we used TAIL-PCR to analyze DNA sequences flanking transposed Tos17 copies in about 700 regenerated plants that possessed genes randomly disrupted by Tos17. We determined thousands of sequences and characterized them by similarity search against a nonredundant DNA database at the Japanese Ministry of Agriculture, Forestry and Fisheries. Some DNA sequences were identical to those of genes encoding rice proteins; for example, sucrose phosphate synthase, Oryza sativa protein kinase 10, and the OSA1 gene for H+-ATPase. Other sequences were very similar to those from various species of plants and animals; for example, the RPB1-C gene for the largest subunit of RNA polymerase II in soybean, and a human DNA sequence from P1-derived artificial chromosome 388M5 on chromosome 22. Others showed a low degree of similarity to the sequences in the database. Approximately 10% of the sequences matched rice expressed sequence tags surveyed in the Rice Genome Research Program.