[Effect of BYDV-MP nuclear localization signal on the movement of PVX]

Area of Science:

• Plant virology
• Molecular biology
• Genetics

Context:

• Investigating plant virus interactions and movement mechanisms is crucial for understanding disease spread.
• Potato Virus X (PVX) and Barley Yellow Dwarf Virus (BYDV) are significant agricultural pathogens.
• The role of viral movement proteins (MPs) in systemic infection is a key area of research.

Purpose:

• To elucidate the role of the BYDV-MP nuclear localization signal in the systemic movement of PVX.
• To determine if BYDV-MP can functionally replace the PVX 25kD movement protein.
• To identify specific amino acid residues within the BYDV-MP nuclear localization signal critical for PVX movement.

Summary:

• Using a PVX-derived vector (pGR107) with Green Fluorescent Protein (GFP) as an indicator, BYDV-MP was introduced into *Nicotiana benthamiana*.
• BYDV-MP induced systemic infection and exacerbated PVX symptoms, even compensating for the absence of the PVX 25kD movement protein.
• Mutational analysis revealed that substitutions at the 5th and 6th amino acids of the BYDV-MP nuclear localization signal only delayed PVX movement, while a mutation at the 7th amino acid completely inhibited it.

Impact:

• This research reveals a novel mechanism of viral synergy and functional complementation between different plant viruses.
• Identifies critical residues in BYDV-MP's nuclear localization signal essential for mediating PVX systemic movement.
• Provides insights into the molecular basis of viral movement and potential targets for disease control strategies.