EPIGENETICS AND TRANSPOSONS. “The hypothesis that transposable elements activated in the vegetative cell generate mobile siRNA that reinforces the methylation and silencing of cognate sperm transposable elements. This hypothesis is consistent with the known ability of small RNAs to move between plant cells.” (siRNA = small interfering RNAs or silencing RNAs).
http://www.sciencedirect.com/science/article/pii/S1534580713000427