The copy number of rice CACTA DNA transposons carrying MIR820 does not correlate with MIR820 expression.

miR820 is a small RNA species (22 and 24 nucleotides), produced from transcripts originated from a region inside CACTA DNA transposons in rice. Because MIR820 is a transposon gene, its expression may depend on the transposon copy number. Here, we investigated the copy number of MIR820 and its expression levels in various cultivars and wild species of rice. We found no correlation between copy number and expression level, suggesting that MIR820 transcription is regulated not by the copy dosage but by the epigenetic state of each copy.