Characterisation of a new potyvirus species infecting meadow saffron Colchicum autumnale).

The alkaloids contained in Colchicum autumnale seeds are used in numerous medicines. Good quality seeds are difficult to obtain from this undomesticated plant. Therefore, a research program was set up aiming to cultivate C. autumnale in order to improve alkaloid contents and seed yields. In this context, a collection was established in 1999 by transplanting corms from twelve different locations in Eastern France. However, serious symptoms of necrosis and decay have appeared in this collection since 2001. Electron microscopic observations of plants showing symptoms revealed the presence of filamentous particles and pinwheel-like structures characteristic of the Potyviridae family. Leaves and corms from symptomatic plants were assayed with potyvirus-specific Enzyme-Linked Immunosorbent Assay test. Positive reactions were obtained with plants from all the geographic origins, which exhibited flower breaking symptoms on petals. RT-PCR tests with family Potyviridae-specific primers confirmed the ELISA results and showed that the virus can be detected in corms, roots and flowers of symptomatic plants. The 3' region of the genome was cloned, sequenced and compared to other potyvirus species. Phylogenetic analyses suggest the presence of a new viral species tentatively named Meadow saffron breaking virus (MSBV) in C. autumnale.