Long-term storage of Phytophthora cultures in water

Abstract

Long-term storage of cultures of Phytophthora species is a challenge for any lab managing a working collection of isolates. Storage in liquid nitrogen is generally considered to be optimal for archival storage, and successful recovery of most species is regularly achieved after many years. Nitrogen storage has its drawbacks, however, especially for a working collection. It requires species specific freezing conditions, and thawing must be done carefully. Equipment is bulky, and regular addition of liquid nitrogen is necessary. Storage in vials in water at room temperature is an efficient, effective alternative for many collections. Isolates are grown on agar, and plugs are removed from the colony margin and placed in sterile water in 1.5 ml plastic tubes, with or without pieces of sterilized hemp seed. Tubes are kept in coded racks at room temperature, in the dark. Agar plugs can be removed one at a time as needed and plated on selective agar to resume growth. In a recent test, we had nearly 100 percent recovery of several Phytophthora species, including P. ramorum, after 7 years in water storage.

Parent Publication

• Proceedings of the fourth meeting of the International Union of Forest Research Organizations (IUFRO) Working Party S07.02.09: Phytophthoras in forests and natural ecosystems

Citation

Sutton, Wendy; Reeser, Paul; Hansen, Everett. 2009. Long-term storage of Phytophthora cultures in water. In: Goheen, E.M.; Frankel, S.J., tech. coords. Proceedings of the fourth meeting of the International Union of Forest Research Organizations (IUFRO) Working Party S07.02.09: Phytophthoras in forests and natural ecosystems. Gen. Tech. Rep. PSW-GTR-221. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 327-330.