Investigation of viral targeting of the argonaute proteins as a trigger of immune responses

Plants and plant viruses are engaged in an evolutionary molecular arms race. Plants employ RNA silencing, which allows plants to target viral transcripts for silencing; however, plant viruses have evolved proteins, known as viral suppressors of silencing (VSRs), which interfere with RNA silencing function. in turn, plants have counter-evolved resistance (R) proteins that directly or indirectly recognize VSRs and elicit a robust anti-viral response known as hypersensitive response (HR), which is a form of programmed cell death. The P0 protein, a VSR encoded by Poleroviruses, perturbs host RNA silencing by specifically targeting the catalytic component of the RNA-Induced Silencing Complex (RISC), known as Argonaute (AGO). P0 targets AGO to degradation by means of autophagy. Nicotiana glutinosa confers resistance to Poleroviruses, and the associated R-protein, designated Rpol, recognizes three different P0 proteins, PLRVencoded P0 (P0PL), Cucurbit aphid-borne yellows virus (P0CA) and Turnip Yellows Virus (P0 TU). The goal of this research is to better understand Rpol function by exploring a role for the AGO family in Rpol-mediated HR. AGO1 degradation was discovered to be insufficient to elicit Rpol response. P0CA, P0PL and P0TU demonstrated shared activity in causing degradation of both AtAGO4 and AtAGO9. Pe recognition in N. glutinosa accession TW59 required N- and C- terminal ends. This work to better understand plant defense against Poleroviruses may help in the development of virus resistant crops.