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ARS Home » Pacific West Area » Corvallis, Oregon » Forage Seed and Cereal Research Unit » Research » Publications at this Location » Publication #260862

Title: Fertilization of Epichloe typhina in cultivated Dactylis glomerata by factors besides Botanophila flies

item RAO, S - Oregon State University
item Alderman, Stephen
item KASER, J - Oregon State University
item HOFFMAN, G - Oregon State University

Submitted to: International Symposium on Fungal Endophytes of Grasses
Publication Type: Proceedings
Publication Acceptance Date: 6/30/2011
Publication Date: 8/31/2012
Citation: Rao, S., Alderman, S.C., Kaser, J., Hoffman, G. 2012. Fertilization of Epichloe typhina in cultivated Dactylis glomerata by factors besides Botanophila flies. Proceedings of the International Symposium on Fungal Endophytes of Grasses. 122-126.

Interpretive Summary: Choke disease, caused by the fungus Epichloe typhina, is one of the most important diseases of orchardgrass grown for seed. The fungus relies on a specific fly for sexual reproduction, but observations in Oregon seed production fields indicated alternate mechanisms of fungal fertilization were occurring. Researchers at Oregon State University and USDA-ARS in Corvallis established alternate mechanisms of fertilization, including rain splashing, slugs, and the sexual spores of the fungus itself. This study provide new information on the biology of choke disease, accounts for the rapid and widespread occurrence of the disease, and provides insight into potential disease controls approaches, which is particularly important as there are currently no disease controls for choke disease in orchardgrass.

Technical Abstract: Epichloë typhina, an endophytic fungus native to Europe, requires spermatia transfer between opposite mating types for fertilization. In wild grasses, Botanophila flies are recognized as vectors for spermatial transfer. However, in cultivated seed production fields of Dactylis glomerata (orchardgrass, cooksfoot) in Oregon, USA, into which E. typhina was inadvertently introduced in the mid 1990s, Botanophila is present but fertilized stromata are abundant in the absence of fly eggs. Our objectives were to determine if alternative mechanisms could fertilize E. typhina in Oregon. Our results indicate that ascospores, the primary means of new plant infection in E. typhina, are abundant and can function as spermatia for fertilization. In addition, slugs, which feed on fungal stromata, and water splash, which can occur from frequent rains in the region, can facilitate fertilization in E. typhina. Thus, besides Botanophila, other biotic and abiotic mechanisms exist for transfer of spermatia for fertilization of E. typhina.