Inhibition of tobacco mosaic virus infection by quercetin and vitexin.

The flavonoids, quercetin and vitexin were proved to reduce lesion number in the local hosts Datura stramonium and Chenopodium amaranticolor infected with Tobacco mosaic virus (TMV). Both flavonoids also reduced the virus concentration in systemically infected tobacco plants. This effect was restricted to an early stage of infection and correlated with an induced synthesis of salicylic acid (SA) and kaempferol suggesting their possible defensive role in the infected plant tissue. Since the tested flavonoids did not bind to the virus particles, their antiphytoviral activity was probably not based on a direct virus inactivation.