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.
Infection by the systemic fungus Epichloë glyceriae alters clonal growth of its host Glyceria striata.
PAN, JEAN1, CLAY, KEITH1, 1
ABSTRACT- Diseases affect growth characteristics and population structure in many nonclonal plant species but the effects of diseases on clonal plant species have not been well studied. The aim of our study was to determine how disease affects host clonal growth in the Glyceria striata-Epichloë glyceriae plant-pathogen system. In a greenhouse study, we found that naturally infected plants had greater clonal growth than naturally uninfected plants. Infected plants produced more stolons and had greater clonal growth biomass than uninfected plants, although total biomass was similar. We then compared growth of infected and disinfected G. striata plants to distinguish between the following two hypotheses: 1) E. glyceriae infection directly changes host clonal growth, and 2) host genets with greater stolon production are more likely to be infected by the pathogen. Results from this experiment support the first hypothesis, that pathogen infection directly affects host clonal growth. Similar to naturally uninfected plants, mother ramets of disinfected plants produced more tillers and had greater biomass than infected plants. Conversely, infected plants produced more stolons and had greater clonal growth biomass than disinfected plants. Again, total biomass was not statistically different. Our results suggest that changes in host growth patterns due to pathogen infection can affect the population structure of the symbionts and the prevalence of the symbiosis within host populations.
KEY WORDS: clonal growth, symbiosis, endophyte, grass