Biological Sciences, School of

 

Date of this Version

Spring 4-14-2020

Document Type

Presentation

Citation

Holste, Natalie M & Garcia-Ruiz, H. (2020, April) Silencing Suppression Activity of a Polerovirus P0 Protein. Graduate Student Spring Research Fair (Cancelled for COVID-19), Lincoln, Nebraska

Abstract

Maize lethal necrosis is an intense viral disease spreading across sub-Saharan Africa. Maize is the staple crop grown in sub-Saharan Africa, but most crops infected with maize lethal necrosis will not survive to harvest. This causes immense economic hardship and starvation within the population. Maize lethal necrosis consists of a combination of two viruses, Maize chlorotic mottle virus (MCMV) and a virus from the genus potyvirus. In a recent study, a Maize yellow dwarf virus-RMV (MYDV-RMV)-like polerovirus, was repeatedly detected in plants with maize lethal necrosis. Poleroviruses have a silencing suppressor, P0 protein, and the mechanism of suppression is poorly understood. In order to understand the mechanisms of silencing suppression, P0 was cloned and tagged. Transient analysis showed it is a strong suppressor of transgene silencing. P0 also restored pathogenicity in trans-complementation assays with two suppressor-deficient viruses, Turnip mosaic virus (TuMV), a potyvirus, and Turnip crinkle virus (TCV), a carmovirus, elucidating that P0 is a suppressor of antiviral silencing. P0 lead to the depletion of secondary small-interfering RNAs (siRNAs) possibly due to the degradation of Argonautes (AGO). P0 was co-expressed with tagged AGO 1, 2, 4, 5, 7, and 10 and caused a drop in all AGOs except AGO 4. Dual suppressor assays show that P0 affects the biogenesis of secondary virus-derived siRNAs. Our results provide novel insights on the mechanism of siRNA silencing suppression by polerovirus P0.

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