The conservation of Ustilago tritici in infected seed

Traditional methods of maintaining strains of Ustilago tritici over long periods of time consume large amounts of labour and physical resources, with variable results. These methods generally involve the storage of teliospores of each isolate at temperatures of 2-4 °C. Very little long-term work has been conducted on the survival of mycelium of U. tritici in infected host seed. Our objective was to determine the survival of race T2 of U. tritici as mycelium in infected wheat seed stored at -15 °C for up to 32 years. There was a significant decline in the per cent viability of the inoculated wheat seed over time. Conversely, there was a significant increase in the per cent infection of the viable seed over time. This suggests that either the cold treatment enhances the survival of the mycelium of the pathogen, or the fungus enhances the survival of the wheat seed at low temperatures. Storage of U. tritici as mycelium in infected seed at -15 °C is an effective technique for longterm preservation of this pathogen. © Her majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada (2010).