DCL3 and DCL4 are likely involved in the light intensity-RNA silencing cross talk in Nicotiana benthamiana.

Plants have substantially invested in RNA silencing as the central defense mechanism to combat nucleotide 'invaders' such as viruses, trasposable elements and transgenes. The quantity and quality of light perceived by a plant is a constant environmental stimulus refining cell homeostasis and RNA silencing mechanism seems not to be an exception In our recent paper in BMC Plant Biology we documented that light intensity, in physiological ranges, positively affects silencing initiation and spread. (1) Here, we show that virus induced gene silecing under high light conditions results in more frequent systemic silencing events of a transgene and is acompanied by elevated DCL3 and DCL4 mRNA levels. In addition, our results show that DCL3 holds a vital role in systemic silencing spread and the positive effect of light intensity on RNA silencing requires DCL4 function.