Pacific Southwest

Title: The maturation and germination of Phytophthora ramorum Chlamydospores

Author: Smith, Aaron L.; Hansen, Everett M.

Date: 2008

Source: In: Frankel, Susan J.; Kliejunas, John T.; Palmieri, Katharine M., tech. coords. 2008. Proceedings of the sudden oak death third science symposium. Gen. Tech. Rep. PSW-GTR-214. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. pp. 451-454

Station ID: GTR-PSW-214

Description: Chlamydospores are a distinctive feature of Phytophthora ramorum. They are formed quickly in agar, and within colonized leaves. We followed their development and maturation in vitro and in vivo, and studied conditions affecting their germination. Cell walls of mature P. ramorum chlamydospores are thicker than reported for other Phytophthora species, although thin-walled chlamydospores are also formed. Chlamydospores formed within rhododendron leaves are smaller with thicker walls than spores formed in vitro. Chlamydospore development begins on hyphae less than two days old, and chlamydospores reach maximum size in about 10 days. Chlamydospores are formed continuously as P. ramorum develops, so spores of all ages are mixed in a colony. Chlamydospores of P. ramorum germinate in vitro at a low but highly variable frequency. In our experiments, the maximum germination obtained was about 13 percent, and the overall average was closer to 3 percent. Germination was higher on V8 agar than on cornmeal agar, and lowest on water agar. Smaller chlamydospores germinated more frequently than larger spores.

Keywords: Phytophthora ramorum, chlamydospores, germination

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Citation

Smith, Aaron L.; Hansen, Everett M.  2008.  The maturation and germination of Phytophthora ramorum Chlamydospores.   In: Frankel, Susan J.; Kliejunas, John T.; Palmieri, Katharine M., tech. coords. 2008. Proceedings of the sudden oak death third science symposium. Gen. Tech. Rep. PSW-GTR-214. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. pp. 451-454.