p22 of Tomato chlorosis virus, an RNA silencing suppressor, is naturally expressed in the infected plant

Authors: ZHAO, R - China Agricultural University; WANG, N - China Agricultural University; LIU, S - China Agricultural University; Ling, Kai-Shu; FAN, ZAIFENG - China Agricultural University; ZHOU, TAO - China Agricultural University

Submitted to: Acta Virologica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/13/2017
Publication Date: 7/13/2017
Citation: Zhao, R., Wang, N., Liu, S., Ling, K., Fan, Z., Zhou, T. 2017. p22 of Tomato chlorosis virus, an RNA silencing suppressor, is naturally expressed in the infected plant. Acta Virologica. 60:423–425. doi:10.4149/av_2016_04_423

Interpretive Summary: Tomato chlorosis virus (ToCV) has emerged as a serious disease problem in field and greenhouse tomato productions in the U.S. and worldwide. This whitefly transmitted virus is difficult to control. An effective and economical means of controlling a viral disease has been to use a tomato cultivar with resistance. On the other hand, viruses have developed a counter defense mechanism using a virus-encoded gene (s) as a ribonucleic acid (RNA) silencing suppressor, leading to resistance breaking. One of these genes in ToCV encoding for the p22 protein has been shown to be a gene silencing suppressor. However, at this time the physical presence of the p22 protein in an infected host plant has not been determined. In the present study, we revealed, for the first time, the natural expression of p22 in a ToCV-infected plant (Nicotiana benthamiana) using an antibody targeting the fusion protein tag. Identification for the presence of RNA silencing suppressor may help us to understand the mechanism of virus pathogenicity, and thus lead to development of a more durable disease resistance cultivar against ToCV.

Technical Abstract: Tomato chlorosis virus (ToCV) in the genus Crinivirus of the family Closteroviridae, is an economically important emerging disease of tomato worldwide. This whitefly-transmitted virus is difficult to control. The best strategy in viral disease management is through the use of a resistant cultivar. However, viruses often develop a counter-defense measure using virus-encoded gene(s) for a RNA silencing suppressor. P22 gene in ToCV has been identified by others as an RNA silencing suppressor, but its presence in the ToCV-infected plant has not been determined. Since an antibody is not yet available for p22, until now, there is no direct evidence showing p22 is expressed naturally in the ToCV infected plants. The objective of the present study was to provide a direct physical evidence for the presence of p22 protein in a ToCV-infected plant. By developing an infectious clone of ToCV with a triple-FLAG tag fused to the C-terminus of p22, using an anti-FLAG monoclonal antibody, we present here, for the first time, a physical evidence for the natural expression of p22 in ToCV-infected Nicotiana benthamiana plant. Understanding of the gene silencing suppressor may help us in developing a tomato cultivar with durable disease resistance to ToCV.