Essential oil composition of Agastache anethiodora Britton (Lamiaceae) infected by cucumber mosaic virus (CMV)

Giant hyssop, Agastache anethiodora Britton, cultivated at the Herb Garden of Casola Valsenio, Italy, has been found for the first time naturally infected by cucumber mosaic virus (CMV). Characteristic symptoms on the leaves were chlorotic or yellow mosaic, ring and line patterns and malformation, followed by yellowing and stunting of the entire plant. CMV was mechanically transmitted to species of the families Chenopodiaceae and Solanaceae and identified by applying PAS–ELISA and RT–PCR techniques. The essential oil of both healthy and CMV‐infected plants has been evaluated by means of GC–FID and GC–MS, with the object of identifying composition differences caused by the disease. The infection of A. anethiodora by CMV was found to induce significant reduction in the yield of essential oil and several changes in the relative composition of the main components: pulegone, menthone, iso ‐menthone, methyl chavicole and limonene. Methyl chavicole content, in particular, was drastically reduced. The importance of the phytopathological status of essential oil‐bearing plants is outlined.