In the case of TGMV, a second viral protein, BR1, is thought to bind to single stranded viral DNA and to mediate transfer through the enlarged plasmodesmata. Name another protein with a function related to that of TGMV BR1. Recently, plant encoded proteins with similarities to viral movement proteins have been discovered. The resemblance included similarity at the protein sequence level and the immunological level, and conservation of the ability to increases plasmodesmatal size exclusion limits. Maybe viral genomes acquired such host genes and thus became less dependent on host factors for viral spread through the plant.
Most plants are resistant to most viruses.
There are few compatible interactions between viruses and host plants. The N gene appears to sense the presence of virus by binding to the TMV replicase protein. During the HR the cells containing virus die, resulting in a small necrotic lesion in the leaf. The HR prevents spread of the virus throughout the plant and contains the virus. Plants infected with one virus often show decreased susceptibility for other viruses.