Skip to main content
ARS Home » Northeast Area » Ithaca, New York » Robert W. Holley Center for Agriculture & Health » Emerging Pests and Pathogens Research » Research » Publications at this Location » Publication #405865
Research Project: Management and Biology of Arthropod Pests and Arthropod-borne Plant Pathogens

Location: Emerging Pests and Pathogens Research

Title: Grapevine fanleaf virus RNA1-encoded proteins 1A and 1BHel individually or cooperatively suppress RNA silencing

Author
item CHOI, JIYEONG - Cornell University
item PAKBAZ, SAMIRA - (NCE, CECR)networks Of Centres Of Exellence Of Canada, Centres Of Excellence For Commercilization A
item YEPES, LUZ - Cornell University
item CIENIEWICZ, ELIZABETH - Clemson University
item SCHMITT-KEICHINGER, CORINNE - (NCE, CECR)networks Of Centres Of Exellence Of Canada, Centres Of Excellence For Commercilization A
item LABARILE, ROSSELLA - (NCE, CECR)networks Of Centres Of Exellence Of Canada, Centres Of Excellence For Commercilization A
item MINUTILLO, SERENA - (NCE, CECR)networks Of Centres Of Exellence Of Canada, Centres Of Excellence For Commercilization A
item Heck, Michelle
item HUA, JIAN - Cornell University
item FUCHS, MARC - Cornell University

Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2023
Publication Date: 3/30/2023
Citation: Choi, J., Pakbaz, S., Yepes, L., Cieniewicz, E., Schmitt-Keichinger, C., Labarile, R., Minutillo, S., Heck, M.L., Hua, J., Fuchs, M. 2023. Grapevine fanleaf virus RNA1-encoded proteins 1A and 1BHel individually or cooperatively suppress RNA silencing. Molecular Plant-Microbe Interactions. https://doi.org/10.1094/MPMI-01-23-0008-R.
DOI: https://doi.org/10.1094/MPMI-01-23-0008-R

Interpretive Summary: Grapevine fanleaf virus (GFLV) causes fanleaf degeneration, one of the most damaging viral diseases of grapevines. The virus is spread by nematodes in nature and via graft propagation of infected material. Negative impacts on yield drive increased costs of grape production due to yield loss, increased costs of vineyard management and vine replacement. Scientific research focused on understanding how GFLV infects grapevines may lead to the development of new management strategies and importantly, the development of virus-resistant grape varieties. In this research, we show new details about how the virus dismantles the plant immune response to GFLV infection. Importantly, it was shown that two viral proteins worked together, either as a single larger unit or individually to target the most critical genes involved in plant immunity to viral infection. The work shows that plant viruses such as GFLV have sophisticated mechanisms to overcome plant defenses and the importance of model plant systems to conduct research on challenging and economically important grape-infecting pathogens.

Technical Abstract: Grapevine fanleaf virus (GFLV) causes fanleaf degeneration, one of the most damaging viral diseases of grapevines. Despite substantial advances at deciphering GFLV-host interactions, how this virus overcomes the host antiviral pathways of RNA silencing is poorly understood. In this study, we identified viral suppressors of RNA silencing (VSRs) encoded by GFLV using fluorescence and gene expression assays in transgenic Nicotiana benthamiana expressing enhanced green fluorescent protein (EGFP). Results revealed that GFLV RNA1-encoded protein 1A, for which a function had yet to be assigned, and protein 1Bhel, a putative helicase, reverse systemic RNA silencing. Proteins 1A and 1Bhel acted individually, together (1A+1Bhel), or as a fused form (1ABhel) predicted as an intermediary product of RNA1 polyprotein proteolytic processing. The GFLV VSRs differentially altered the expression of plant host genes involved in RNA silencing, as shown by RT-qPCR. In coinfiltration assays with an EGFP hairpin construct, protein 1A upregulated NbDCL2/4 and NbRDR6, and proteins 1Bhel and 1A+1Bhel upregulated NbDCL2/4, MbAGO1/2 and NbRDR6, while protein 1ABhel upregulated NbAGO1 and NvRDR6. In a reversal of systemic silencing assay, protein 1A upregulated NbDCL2 and NbAGO2, and protein 1ABhel upregulated NbDCL2/4 and NbAGO1. This is the first report of two VSRs encoded by a virus that act individually or cooperatively as a fused form to counteract the systemic antiviral host defense, suggesting GFLV encodes a unique, counter-defense strategy to interfere with various steps of the plant antiviral pathways of RNA silencing during infection.