Mechanisms of RNA-Mediated Resistance to Plant Viruses

Viral diseases cause significant losses to almost all crops throughout the world. Infections with plant viruses can either cause direct yield losses or lead to unacceptable levels of postharvest damage to the crops. Besides measures to limit the virus incidence, the ultimate way to minimize losses caused by viral infections is the production of resistant varieties. This can be obtained by introgression of resistance genes from wild relatives, or by transformation of host plants with antiviral genes or viral sequences. Expression of viral coat protein (CP) in plants yields protection to the homologous virus. In addition to this CP-mediated protection (CPMR), a still growing number of reports deal with engineered virus resistance conferred by transgenic expression of viral transcripts, rather than proteins.