The effect of the glucosinolate sinigrin and of allyl isothiocyanate on the infectivity of turnip mosaic virus

Abstract

The effect of the glucoainolate sinigrin applied at concentrations from 5×10-6 to 5 × 10-3 g cm-3 on the infectivity of two isolates of turnip mosaic virus (TuMV) was studied. A statistically highly significant linear correlation relationship was found between the concentration of sinigrin added to the sap prepared from infectious plants ofPetunia hybrida hort. Vilm. cv. Lavina and the infectivity of the virus, expressed in the number of local necrotic lesions onNicotiana tabacum L. cv. Samsun leaves. Sinigrin caused a statistically significant decrease in the virus infectivity already at a concentration of 5 × 10-5 g cm-3. This virocidal effect of sinigrin was not dependent on the virus isolate applied and was not influenced by the host plantsP. hybrida andNicotiana glutinosa L. A statistically highly significant decrease in the virus infectivity was also caused by sinigrin applied at a concentration of 5 × 10-3 g cm-3 in the sap from infectiousSinapis alba L. andBrassica nigra (L.) Koch plants, in which case its enzymic degradation to allyl isothiocyanate was observed. When these plants were homogenized in 0.5 M phosphate buffer pH 8.5, no statistically significant decrease in the infectivity of the virus was observed. Purified virus preparations in 0.5 M phosphate buffer pH 7.5 were not affected by sinigrin applied at the concentration of 5 × 10-3 g cm-3. The significance of the content of glucosinolates in the pathophysiology of theBrassicaceae and in their resistance to viruses and other pathogens is discussed.