Resistance of potato to cucumber mosaic virus appears related to localization in inoculated leaves

Although CMV can cause extensive damage to solanaceous crops like tomato, tobacco and pepper, it has little if any impact on the related crop, potato. To better understand this phenomenon, we have tested 32 potato genotypes for susceptibility or resistance to local and systemic Fny-CMV infection. Using ELISA, all genotypes appeared to show virus replication in leaves that were mechanically inoculated. In contrast, only ten genotypes exhibited systemic spread as expressed by significant CMV titers in new growth. These data suggest that, although CMV can replicate in potato cells and appears to spread short distances cell-to-cell, long distance movement appears to be blocked in most potato genotypes. Therefore, the general resistance of potato crops to CMV infection may be related to virus localization at points of entry.