First report of Vitis cryptic virus from grapevines in China

Area of Science:

• Plant Virology
• Molecular Biology
• Genomics

Background:

• Vitis cryptic virus (VCV) was first identified in Japan in 2021.
• VCV is tentatively classified in the genus Deltapartitivirus, possessing a two-segmented genome encoding RNA-dependent RNA polymerase (RdRp) and coat protein (CP).

Purpose of the Study:

• To identify and characterize Vitis cryptic virus (VCV) in China.
• To confirm the graft transmissibility of VCV.
• To assess the incidence and distribution of VCV in Chinese grapevines.

Main Methods:

• Next-generation sequencing (Illumina NovaSeq 6000) of grapevine RNA.
• Bioinformatic analysis including read mapping, de novo assembly (rnaviralSPAdes), and BLAST.
• RT-PCR using specific primers for VCV RdRp and CP genes.
• Grafting experiments to assess VCV transmissibility.

Main Results:

• VCV was identified in a grapevine cv. Jinhuanghou in China, with genomic segments showing high nucleotide identity to the Japanese isolate.
• RT-PCR confirmed VCV infection, and sequencing of amplified products further validated the presence of the virus.
• Grafting experiments demonstrated that VCV is graft-transmissible, inducing chlorotic mottling symptoms.
• A survey revealed VCV in 2.6% of sampled grapevines across 21 provinces, with notable presence in Jilin and Liaoning provinces.

Conclusions:

• This study reports the second occurrence of Vitis cryptic virus (VCV) globally and the first confirmation of its graft transmissibility.
• The presence of VCV in important Chinese grapevine cultivars highlights the need for further research into its pathogenicity and impact.
• Understanding VCV distribution and transmission is essential for developing potential management strategies in China.