Abstract
Transposable elements comprise majority of eukaryotic genomes where they contribute to genome evolution and diversification. Although Miniature inverted repeat transposable elements (MITEs) don't have the coding capacity of transposition, they successfully attain high copy numbers (>1,000 or >10,000) in a short time. However, the mechanism of causing rapid MITE amplification ha yet to be mentioned because these multiple amplifications happened millions years ago. Recently, we caught recent MITE (mPing) amplification (>1,000) in four japonica rice strains (EG4 and several landraces), despite most of japonica strains including Nipponbare have only 50 copies. Ping and Pong are known for autonomous elements of mPing. Here, we revealed that although Pong has almost no transcription and high methylation status in promoter and ORF regions, Ping is still transcribed even in Nipponbare with lack of methylation of all C sites (CG, CHG and CHH) at promoter region like active genes, and Ping dosage effect should be resposible for rapid mPing amplification in the genome.
