Discipline: Ecology Environmental and Earth Sciences
Room: Exhibit Hall A
Erinn R Dady - University of Illinois at Urbana-Champaign
Co-Author(s): Isako B. Di Tomassi, Community College of Philadelphia, Philadelphia, Pennsylvania; Neha Chatterjee, Department of Crop Sciences, College of ACES, University of Illinois at Urbana-Champaign, Urbana, Illinois; Andrew Margenot, Department of Crop Sciences, College of ACES, University of Illinois at Urbana-Champaign, Urbana, Illinois; Esther N. Ngumbi, Department of Entomology, College of Liberal Arts & Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois.
Arbuscular mycorrhizae fungi (AMF) are naturally occurring, beneficial fungi that grow in mutualism with many plants by colonizing their roots. Associations between host plants and AMF enhance plant defense responses, including production of volatile organic compounds (VOCs). Previous studies show the outcomes of AMF-plant mutualism vary depending on fertilization and insect herbivory. Our study tested the hypothesis that AMF mutualism improves plant volatile signaling under conditions of nutrient limitation, following exposure to insect herbivory. This work is important because it could help identify novel approaches to pest management. We used a model system consisting of consisting of tomato plant (Lycopersicon esculentum) and the herbivorous pest, tobacco hornworm (Manduca sexta). To isolate mechanisms of AMF mutualisms, we used two tomato genotypes a) Myc, mycorrhizal wild-type tomato, easily colonized by AMF (6-30% reported); and b) Rmc, reduced mycorrhizal mutant, resists colonization by AMF (<2% reported) Tomato plants were grown under low- and high-phosphorous soils. Volatiles were collected from undamaged, mechanically damaged and herbivore damaged plants. To induce the production of herbivore-induced volatiles, four, fourth instar M. sexta larvae were allowed to feed on tomato plants 48 hours prior to volatile collection. Four replicates were done. Volatiles were collected using solid phase microextraction and identified using gas chromatography mass spectrometry. Results showed that soil fertility and mycorrhizal colonization affected the emissions of herbivore-induced VOCs in tomato. Overall, 28 VOCs were identified in detectable quantities. As predicted, VOC emissions differed by genotype, with the AMF colonized plants in low fertility responding strongest to insect herbivory. The implication of this finding should be considered particularly in the use of AMF to manage agricultural pests, as many herbivores and their natural enemies are known to use plant VOCs as host location cues. More understanding of these mechanisms could help lower the need for fertilizer and pesticide applications while improving yields and reducing insect damage to crop plants. This would be beneficial to the farmers? bottom line as well as the environment. Further research will focus on tomatoes grown in realistic field conditions to unravel additional mechanisms.
Funder Acknowledgement(s): Financial support was provided by the National Science Foundation under grant #NSF REU 1559908/1559929, as part of the Phenotypic Plasticity Research Experience for Community College Students, through the University of Illinois at Urbana-Champaign Institute for Genomic Biology and Parkland College. http://precs.igb.illinois.edu/
Faculty Advisor: Esther N Ngumbi, email@example.com
Role: I participated in all aspects of the experiment. I dug soil from local fields, planted seeds, and cared for seedlings. I also assisted in volatiles collection and identification. Later, I recorded weights of 192 Manduca sexta, used to induce the emission of herbivore-induced VOCs and recorded above- and below ground biomass for dry weight of all plants.