PARENT SESSION
Poster Session 35: Evolutionary Ecology
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Chemical Phenotypes of Ripe Fruit: The Importance of Microbial Pathogens.
Reagan, Karen*,1, Tewksbury, Joshua1, 1 University of Washington, Seattle, WA, USA
ABSTRACT- Secondary metabolites, chemicals in plants that have no obvious function in primary growth, are present in many plants, but the importance of these chemicals are still poorly understood. Secondary metabolites in ripe fruit may function to increase the effectiveness of beneficial fruit consumers, or to deter fruit consumers that are consistently harmful to the seeds. While many vertebrates are beneficial seed dispersers others are seed predators and differences in vertebrate physiology make targeting of vertebrate consumers by means of secondary metabolite production difficult. Under the hypotheses known as Defensive Tradeoff, secondary metabolites may instead target microbial fruit consumers since they are always detrimental consumers of the fruit and never, under any circumstances, act as seed dispersers. The genus Capsicum (family Solanaceae) presents an ideal model for the study of secondary metabolites in fruit. Capsicum species produce capsaicin as a secondary metabolite, the fiery tasting chemical that is responsible for pungency and gives chili peppers their spicy flavor. Utilizing C. chacoense, a chili plant that is polymorphic for the characteristic of pungency, the viability of both pungent and non-pungent seeds affected by the microbial seed predator Fusarium was tested. Each seed was then assigned a score for the level of Fusarium infection ranging from 1-10 and subsequently tested for viability using a 0.05% tetrazoleum solution. Preliminary data indicates that the presence of capsaicin results in lower infection rates of Fusarium. The results of this experiment will help illuminate previously uninvestigated interactions between secondary metabolites in fruits and microbial seed predators that have potentially affected the fruits' evolutionary state.
Key words: secondary metabolites, capsaicin, fusarium, defensive tradeoff