Abstract: Wheat yellow mosaic virus （WYMV） is a member of the genus Bymovirus in the family Potyviridae. WYMV has two single\|stranded positive sense RNA genomes which produce 10 viral proteins. Among those proteins， viral genome\|linked protein （VPg）， which binds to the 5′ end of the viral RNA genome， is predicted to contain a nuclear localization signal （NLS） and nuclear export signal （NES） in the N\| and C\|terminal portions， respectively. WYMV（Wheat yellow mosaic virus） VPg fused to C\|terminus of enhanced green florescent protein （eGFP\|VPg） exclusively accumulated in the nucleus of epidermal cells of Nicotiana benthamiana plants. Fibrillarin， a nucleolus resident protein， was introduced into eYFP（n） plasmid. To investigate the regions of the VPg domain binding fibrillarin， a series of VPg mutant and fibrillarin performed BiFC assay. The result display VPg localized and interact with fibrillarin in the nucleus. NLS but not NES is required for interact with fibrillarin.

Key words: Wheat yellow mosaic virus, VPg protein, nuclear localization, fibrillarin, protein interaction