Summary auto-generated
This study examined the functional interchangeability of movement and coat proteins between two closely related tripartite RNA plant viruses: alfalfa mosaic virus (AMV) and Prunus necrotic ringspot ilarvirus (PNRSV). Researchers created chimeric AMV RNA 3 molecules where the movement protein (MP) gene, coat protein (CP) gene, or both were replaced with corresponding PNRSV genes. These chimeric viruses were tested for replication in protoplasts derived from transgenic tobacco plants expressing AMV replicase genes, and for cell-to-cell movement in these transgenic plants. Results showed that chimeric viruses with PNRSV proteins could replicate in protoplasts and exhibited low-level cell-to-cell movement in plants, though with reduced efficiency compared to wild-type AMV. The PNRSV coat protein could effectively substitute for AMV coat protein in supporting RNA accumulation, while substitution of the movement protein resulted in significantly lower viral RNA levels in plants. These findings suggest that while the movement protein may influence host specificity, it is not the sole determinant, and functional interactions between movement and coat proteins may be important for efficient virus replication and spread.
Key findings
- Chimeric viruses with PNRSV coat protein genes replicated nearly as efficiently as wild-type AMV in protoplasts, showing the CP genes are functionally similar between these related viruses
- Replacement of the movement protein gene with PNRSV MP allowed only low-level cell-to-cell movement in plants, suggesting host specificity involves additional factors beyond the MP gene
- The construct containing both PNRSV MP and CP genes achieved the highest viral RNA accumulation in plants, indicating potential interaction between movement and coat proteins for optimal viral replication
- All chimeric constructs were capable of encapsidation by coat proteins and could support viral RNA synthesis, demonstrating basic functional compatibility between AMV and PNRSV viral proteins
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Abstract
Alfalfa mosaic virus (AMV) and Prunus necrotic ringspot virus (PNRSV) are tripartite positive-strand RNA plant viruses that encode functionally similar translation products. Although the two viruses are phylogenetically closely related, they infect a very different range of natural hosts. The coat protein (CP) gene, the movement protein (MP) gene or both genes in AMV RNA 3 were replaced by the corresponding genes of PNRSV. The chimeric viruses were tested for heterologous encapsidation, replication in protoplasts from plants transformed with AMV replicase genes P1 and P2 (P12 plants) and for cell-to-cell transport in P12 plants. The chimeric viruses exhibited basic competence for encapsidation and replication in P12 protoplasts and for a low level of cell-to-cell movement in P12 plants. The potential involvement of the MP gene in determining host specificity in ilarviruses is discussed.