Differing requirements for actin and myosin by plant viruses for sustained intercellular movement

Area of Science:

• Plant Virology
• Cell Biology
• Cytoskeletal Dynamics

Background:

• The actin cytoskeleton plays a role in the movement of many plant and animal viruses.
• Mechanisms of actin-mediated viral transport and the range of viruses involved are not fully understood.

Purpose of the Study:

• To investigate the role of microfilaments and myosins in the intercellular movement of RNA-based plant viruses.
• To understand the molecular basis for differential requirements of viruses for actin-based transport.

Main Methods:

• Disruption of microfilaments using chemical inhibitors.
• Comparison of subcellular localization of viral proteins using GFP fusions.
• Virus-induced gene silencing of myosin genes in Nicotiana benthamiana.

Main Results:

• Intercellular movement of tobacco mosaic virus (TMV), potato virus X (PVX), and tomato bushy stunt virus (TBSV) was inhibited by microfilament disruption.
• Turnip vein-clearing virus (TVCV) movement was not affected by microfilament disruption.
• TMV protein localized to microfilament-associated inclusions, while TVCV protein did not.
• Silencing of Nicotiana benthamiana myosin XI-2 gene specifically inhibited TMV movement.

Conclusions:

• RNA viruses exhibit diverse evolutionary strategies regarding their reliance on microfilaments and myosin motors for intercellular movement.
• Viral protein interactions with the actin cytoskeleton are key determinants of these differing requirements.
• Phylogenetic relationships do not consistently predict the dependence of viruses on actin-based transport mechanisms.