Phenolic compounds and the hypersensitivity reaction in nicotiana tabacum infected with tobacco mosaic virus

The hypersensitivity of Nicotiana tabacum cv. Xanthi to tobacco mosaic virus infection leads to the production and accumulation of a great number of phenolics (flavonol glycosides, caffeoylquinic, feruloylquinic and p-coumaroylquinic acids, glucose esters and glucosides of cinnamic and benzoic acids). An increase in temperature inhibits the hypersensitive reaction, resulting in the disappearance of these substances. The differences between the healthy and infected leaves become important when the synthesis of the virus is practically brought to completion and the hypersensitivity taken hold. The phenolic compounds do not appear to be responsible for the necrotic hypersensitivity and their production is one of the secondary effects of the virus infection.