Time Lapse (over two weeks) of the GFP gene being switched off in N.benthamiana by mobile small RNAs that were initiated by injection of a hairpinRNA construct into a lower leaf.

In the side branch, the signal reaches the meristem and the silencing is 100% (all pink) from then on.

In the main stem, the sRNAs are chasing the growing tip but have not caught up yet.