A Transposon Triggers Multiple Silencing Pathways During Maize Development

Transposable element activity represents a fundamental threat to the integrity of both plant and animal genomes.  In order to confront this threat, systems of epigenetic silencing have evolved whose function is to repress expression of transposable elements and thus immobilize them.  Although systems of epigenetic regulation have diversified in plants, the one thing that they all share is their capacity to target transposable elements.  Here we present evidence that a single transposon in maize appears to illicit nearly every known plant silencing system, including translational repression, post-transcriptional gene silencing, transcriptional gene silencing, both trans and cis-acting silencing, small RNA mobility, somatically and trans-generationally transmitted silencing and DNA methylation-dependent and independent silencing pathways.  This extraordinary diversity of responses to a single transposon in a single plant suggests that the one theme that unifies all epigenetic silencing in plants is transposon control.