FAVORED EXPLANATION. “The RNA cache, on the other hand, Lolle proposes, is tapped when plants are under stress and is perhaps more than a one-time, random event. It is maintained outside the normal genomic context, inherited, and copied back into the DNA. There is a strong precedent for this mechanism to reside in RNA action.”
http://www.the-scientist.com/?articles.view/articleNo/26000/title/Mendel-upended-/