Jones, Dalton (Weber State University)
Faculty Advisor: Schramm, Katharina (Science, Botany)
Tomatoes (Solanum lycopersicum) are an important agricultural crop around the world. In order to produce food with less impact on the environment, many researchers are looking to utilize natural systems to maximize production with minimal inputs. Maximizing tomato defenses is one possible way to increase productivity. Tomatoes produce both physical and chemical defenses in response to the stress. Increasing the number of trichomes on the plant is a physical means of deterring insects from eating the plant. Trichomes come in two forms glandular trichomes and non-glandular trichomes. The non-glandular trichomes are strictly a physical defense while the glandular trichomes produce chemical defensive compounds against a wide variety of insects. Most land plants can form a symbiosis with arbuscular mycorrhizal fungi (AMF). This symbiosis has been shown to increase nutrient supply, decrease drought stress, and prime plant defenses, all increasing a plant's ability to withstand herbivory stress better. This study examines the response of trichomes and the number of chemical defenses after insect herbivory has occurred with the additional support of the AMF symbiosis. Treatments were exposed to Manduca sexta to stimulate trichome and chemical production. The extracted leaves were analyzed via gas chromatography to examine the make-up of the tomato's chemical defenses. The growth rates of M. sexta were recorded to examine the effects of tomato's chemical defenses after feeding the insects the induced tomato leaves. Measuring trichome density quantifies the change in physical defenses. The addition of the AMF increased the plant defenses, both the number of trichomes present on the plants and the quantity of the chemical defenses. Insects feeding on plants with increased defenses were also shown to have decreased growth. This study shows an alternative strategy for the use of commercial pesticides, lessening the impact of tomato crops on the ecosystem.