PARENT SESSION
Oral Session #53: Co-evolved species interactions: Mutualisms and parasitism. Presiding: A. Krist.
Wednesday, August 8, 2001. 1:00 PM to 4:45 PM. Hall of Ideas F.
Horizontal transmission of Neotyphodium in Arizona fescue populations.
Hamilton, Cyd1, Faeth, Stan1, 1
ABSTRACT- Neotyphodium is an asymptomatic, maternally transmitted endophyte infecting both agronomic and native grasses. Neotyphodium in agronomic Tall Fescue reduces herbivory by both vertebrate and invertebrate herbivores and increases resistance to drought. However, Neotyphodium infection in the native perennial bunch grass Festuca arizonica does not confer the same benefits. Instead, in some instances infection promotes herbivory and provides no clear benefit under drought conditions. These studies suggest that Neotyphodium may be pathogenic to F. arizonica. However, infection status of the host population remains high, 50%-100%. High infection rates coupled with maternal transmission are puzzling since one would expect reduced infection rates if the host population is not receiving some benefit from infection. Neotyphodium may not be limited to maternal (vertical) transmission and may be transmitted horizontally. Occurrences of both transmission pathways would explain the high infection rate within the grass populations and mild pathogenicity of the fungus. Preliminary laboratory studies suggest that horizontal transmission occurs infrequently.
KEY WORDS: Neotyphodium, Mutualisms, Transmission