Identification of a Rice Autonomous DNA Transposon aDart

Abstract

A rice DNA transposon nDart is a non-autonomous element that was found from a mutable virecent line and its excision activity is controlled by an active autonomous element, aDart. A map-based cloning indicated that aDart is identical to an inactive element iDart1-27 (inactive Dart1-27) residing on chromosome 6 in Nipponbare that is probably silenced by epigenetic regulation. To test this hypothesis, cloned iDart1-27 was grown in E. coli in order to release its methylation state in Nipponbare and introduced into plants together with nDart. The results clearly demonstrated that the cloned iDart1-27 element is capable to act as aDart and to excise the nDart element. We can thus conclude that iDart1-27 in Nipponbare is an epigenetically silenced autonomous element.