“Variation in Trichome Density, Latex Inducibility, and Resistance Against a Specialist Insect Herbivore in Natural Populations of Common Milkweed”

Project Summary:

The common milkweed, Asclepias syriaca, a native weedy plant that occurs throughout eastern North America, is the major food source for migrating monarch butterflies (Danaus plexippus) and their larvae. When damaged, milkweed plants immediately exude a sticky, gelatinous, milky-white substance known as latex that serves as a physical barrier to herbivores. This latex, along with all other plant parts, contains cardenolides of varying polarity and effectiveness against herbivores. The growth rate of Danaus plexippus is related to the amount of latex produced from abrasions, leaf cardenolide concentrations, and the presence of leaf trichomes. However, the causes of variation in these traits among natural populations of A. syriaca are poorly known.

Here we measured two defensive traits, latex inducibility and density of leaf trichomes, as well as Monarch larva performance on ~200 A.syriaca accessions. We found that there were high variations of latex response among different accessions post larva damage. Also, the greater the amount of leaf trichomes present, the more latex the caterpillars ingested, and the greater risk of death. Studying the phenotypic variation amongst natural accessions of milkweed allows us to identify the genetic and molecular basis of A. syriaca in future studies.

My Experience:

Over the past 10 weeks, I’ve improved several of my lab skills, made impactful connections, and have gained more knowledge than my brain can hold. My mentor, and friend, Jing Wei, has taught me different lab techniques, showed me how to be an independent researcher, and has challenged me to become a better problem solver. I am now excited and prepared more than ever to conduct my own research in the future. I have discovered my love for plant genomics research, and can fully appreciate all of the hard work and failure that goes into research.