Comparative Analysis of Biological Characteristics among P0 Proteins from Different Brassica Yellows Virus Genotypes
by
, ,
Xiao-Yan Zhang
1,2,†, 
Yuan-Yuan Li
2,3,†,
Ying Wang
2,
Da-Wei Li
2,
Jia-Lin Yu
2 and
Cheng-Gui Han
2,*
1
School of Agriculture, Ludong University, Yantai 264025, China
2
State Key Laboratory for Agrobiotechnology, Ministry of Agriculture and Rural Affairs Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing 100193, China
3
Department of Plant Biology and The Genome Center, College of Biological Sciences, University of California, Davis, CA 95616, USA
*
Author to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Biology 2021, 10(11), 1076; https://doi.org/10.3390/biology10111076
Submission received: 23 September 2021
/
Revised: 17 October 2021
/
Accepted: 19 October 2021
/
Published: 21 October 2021
(This article belongs to the Special Issue Recent Advances in Molecular Plant Pathology)
Simple Summary
Polerovirus P0 proteins are multifunctional proteins. Besides their viral suppressor of RNA silencing (VSR) functions, several P0 proteins can induce a cell death phenotype within the infiltrated region of Nicotiana benthamiana or Nicotiana glutinosa. Recently, the Brassica yellows virus (BrYV) genotype A P0 protein (P0BrA) was identified as a strong viral suppressor of RNAi. In this study, we compared the features of the P0 proteins encoded by different genotypes of BrYV and revealed their difference in inducing cell death in N. benthamiana. Key residues in P0BrA for inducing cell death were also identified. We also showed that all three BrYV genotypes had synergistic interaction with PEMV 2 in N. benthamiana. This study provides theoretical guidance for controlling the viral disease caused by poleroviruses in the future.
Abstract
Brassica yellows virus (BrYV) is a tentative species of the genus Polerovirus, which has at least three genotypes (A, B, and C) in China. The P0 protein of BrYV-A (P0BrA) has been identified as a viral suppressor of RNA silencing (VSR), which can also induce cell death in infiltrated Nicotiana benthamiana leaves. In this study, we demonstrated that the cell death induced by P0BrA was accompanied by the accumulation of reactive oxygen species (ROS) and increased Pathogenesis-related protein genes-1 (PR1) expression. Meanwhile, this cell death phenotype was delayed by salicylic acid (SA) pretreatment. Biological function comparison of the three P0 proteins showed that transiently expressed P0BrB or P0BrC induced a significantly delayed and milder cell death response compared with P0BrA. However, like P0BrA, they also suppressed local and systemic RNA silencing. Six residues of P0BrA essential for inducing cell death were identified by comparative analysis and amino acid substitution assay. We also show that all three BrYV genotypes have synergistic interactions with pea enation mosaic virus 2 (PEMV 2) in N. benthamiana. This study provides theoretical guidance for controlling the viral disease caused by poleroviruses in the future.
Keywords:
Brassica yellows virus; P0; RNA silencing suppressor; cell death
