Characterization of a DMC1 homologue, RiLIM15, in meiotic panicles, mitotic cultured cells and mature leaves of rice (Oryza sativa L.)

DMC1 is one of the most important genes involved in meiotic homologous recombination in Saccharomyces cerevisiae. Homologues of DMC1 have been isolated recently from some plant species, and in this study, we characterized the structure and expression of a DMC1 homologue, RiLIM15, in a Japonica rice, strain A58. RiLIM15 was found to be a gene family consisting of two genes, RiLIM15 and RiLIM15B, in the rice genome. The DNA sequence of RiLIM15A was highly homologous with that of RiLIM15B in the exon regions, although it was less homologous with that of RiLIM15B in the intron regions. Analysis for the expression of RiLIM15 by a combination of Southern blot hybridization and reverse transcription-polymerase chain reaction (RT-PCR) showed that RiLIM15 was expressed not only in meiotic young panicles, but also in mitotic cultured cells, although not in the mature leaves. Analysis of the sequences of these RiLIM15 cDNAs amplified by RT-PCR showed that the sequences of exon 5 were deleted from the cDNAs derived from the meiotic young panicles. Also, exons 5, 10 and 11, as well as 29 bp of exon 8, were deleted from some types of cDNA from the mitotic cultured cells. These results suggest that these deletions map be caused by alternative splicing.