Colgate students have fanned out across the globe to apply their liberal arts know-how in a variety of real-world settings. They are keeping our community posted on their progress. Christine Horn ’19, from Corning, N.Y., wrote this dispatch about her research, funded through the Beckman Scholars Program.
Has the agriculture industry’s selection of redder, juicier, more flavorful tomato fruits come at the cost of reduced defensive abilities in tomato plants? With professor Frank Frey, I will conduct a two-year independent research project that aims to answer this question. The research investigates volatile organic compound (VOC) expression in cultivated, heirloom, and wild type tomato plants in response to various types of herbivory — the consumption of plants by animals.
When a species of plant is attacked by herbivores, it may release chemicals as a defense mechanism. There are two schools of thought on how this mechanism works: some studies suggest that increased VOC emission attracts parasitic and carnivorous insects that eat the herbivores, whereas others suggest that increased VOC emission deters herbivores directly through adverse chemical accumulation in leaves.
In Colgate’s greenhouse, I am growing 120 cultivated tomatoes (which have been highly selected for in terms of color, smell, and other traits), 120 heirloom tomatoes (which have been intermediately selected for), and 120 wild type tomatoes (which have not been selected for at all). I will expose these tomato plants to a half-dozen different experimental herbivory treatments, including mechanical damage (hole punching), chemical induction with methyl jasmonate, as well as attacks by tomato hornworm moth eggs and caterpillars.
To collect data, I measure the VOCs from both the leaves and the air using a gas chromatographer. I gauge the amount of lycopene (the chemical that gives tomatoes their red color) using a spectrophotometer. I also measure smell, taste, acidity, and other traits so I can accurately correlate the defensive abilities of tomatoes with certain expressed traits that may be selected for in the agriculture industry.
The expected outcomes of this research are exciting. Understanding how VOC expression differs in response to herbivory treatments is a critical first step in evaluating whether selection for increased fruit quality has come at the cost of reduced defensive ability. Results may provide the framework for novel mechanisms that reduce agricultural dependency on pesticides.
In addition, this research could provide important insight into agricultural effects on global climate change. VOCs already supply a significant amount of the atmospheric carbon load and have the potential to produce tropospheric ozone, a harmful greenhouse gas. If cultivated tomatoes, in response to herbivory, produce certain volatiles in different proportions relative to other tomato types, they could affect atmospheric carbon load and impact global climate change.
I am extremely excited to have the opportunity to be conducting this research for the rest of my time as a student at Colgate, and I can’t wait to see where it will take me.