Long-Term Storage of Ustilago tritici

An extensive collection of isolates of Ustilago tritici from around the world is maintained at the Cereal Research Centre. As the collection size increases, however, the time and effort needed to maintain the collection becomes greater, as does the need for a good technique for long term storage of U. tritici. Race T2 of U. tritici was inoculated to spikelets of wheat in February 1976. The matured inoculated heads were thrashed and the seed stored in a desiccator with silica-gel at -15°C. Every 2 years, 60 seeds were removed and planted to determine viability and proportion of infected adult plants. Between 57 and 83% of the seed produced adult plants, and the percent of infected plants ranged between 56 and 98% during the 20 years. There was no significant change in seed germination over time, but there was a positive relationship (P < 0.0664, R2 = 0.452) between the time of storage and the arcsine of the proportion of smutted plants. Storage of U. tritici in infected seed at -15°C and low relative humidity is an efficient method for long-term storage of this fungus.