The diseased plant; Economic considerations; Pathophysiological alterations; Pathogenesis-related proteins; Viruses as pathogens; Virus transport in plants; Variability of plant viruses; Genetic basis of host specificity of plant viruses; Aphid transmission of plant viruses; Virus transmission; Spatiotemporal determinants in plant virus epidemics: development of a conceptual model; Disease control; Disease management; Tissue culture; Disease resistance mechanisms; Genetically engineered resistance: transgenic plants.