Mobilization of a retrotransposon in 5-azacytidine-treated fungus Fusarium oxysporum

It is well known that DNA methylation is involved in the control of transposable elements in eukaryotic cells. Recent studies indicate that demethylation of DNA in a mutant of Chlamydomonas and Arabidopsis causes transcriptional activation and mobilization of transposons. In this report, transposition of a retrotransposon was investigated in the phytopathogenic fungus Fusarium oxysporum treated with 5-azacytidine (5azaC), a reagent that causes reduction in the DNA methylation level. The results showed elevated transposition frequency in 5azaC-treated isolates when they were incubated for a long time. However, increase of retrotransposon transcripts was not observed, suggesting that the retrotransposon was mobilized by a mechanism other than its transcriptional activation.