In vitro characterization of viral suppressors of plant silencing
Small RNA-mediated RNA silencing is the main adaptive immune response of higher plants against (+)-strand RNA viruses. RNA induced silencing complexes (RISC) containing AGO nucleases are directed by short RNAs termed small interfering (siRNA) to specific sites within viral RNA molecules. On these sites cleavage occurs inhibiting viral replication, translation and spread. Different viruses independently developed several proteins counteracting this defense mechanism. Tombusvirus p19 and Carmovirus coat protein (p38) are such viral suppressors of RNA silencing (VSRs). Both are already investigated in vivo. These approaches are disadvantageous for distinguishing different activities of the VSRs or for the separation between their direct or indirect effect on plants’ physiology.
In this project I will use an in vitro system (the BY-2 lysate) to investigate the different proposed influences of p19 and p38 on plants’ immune response individually. I will perform studies to compare the two mentioned VSRs concerning their influence in RISC formation and RISC activity to uncover their role in inhibition of RNA silencing.
Supervisor: Prof. Sven Erik Behrens