Viral Determinants of Resistance Versus Susceptibility

Abstract

The ability of a plant virus to systemically infect its hosts can be considered the consequence of a series of interactions between the viral genome and its gene products with the host. Once a virus enters the cell, it must be able to express each of its proteins, replicate its genome, move from one cell to another, and then gain access to the host vascular system to move out of the initially infected leaf to other parts of the plant. At each step of this process, there must be a basic level of compatibility between the virus and its host; otherwise, the infection process ends prematurely. (2002) discusses how mismatches between host and virus at different points of the infection process can define the host range of a virus. For example, stringent requirements for cell-to-cell movement in the plant can provide one important barrier that limits the host range of a virus. A virus may be able to replicate in an individual cell, but its cell-to-cell movement protein may be non-functional in that host, thereby limiting its movement into adjacent cells. In this instance, there would be no visible response of the plant to the inoculation of the virus.