Arianna Nimocks
Faculty Advisor: Georg Jander
Year: 2017

“Determining the functions of herbivore-inducible maize genes on defense against Spodoptera exigua

Project Summary

The survival and fitness of plants is affected by a wide variety of biotic and abiotic stresses; hence plants must defend themselves. Jasmonic Acid (JA) is a plant hormone induced by insect feeding and helps plants defend themselves by producing chemicals that harm the attacking insects or attract their predators.

However, there is much less research on the JA signaling pathway in monocots, such as maize, as compared to dicots. Our project, therefore, is focused on testing the functions of two herbivore-inducible genes in maize that may have roles in affecting JA flux. These genes are highly induced in maize after herbivory, pointing to their importance in plant defense. Even though the homolog of the first gene (Allene Oxide Cyclase2, AOC2) is reported to have a role in JA biosynthesis in dicots, its role in monocots has not been described.

The second gene (IAA-Amidase), despite its high induction, has not been described to affect herbivore resistance in any other plant species. In both projects, we used the reverse genetics approach to reduce the transcript levels of the genes and test the effect of gene silencing on the herbivore-induced jasmonate and metabolite accumulation and on caterpillar performance. Our results suggest that these genes affect the herbivore-induced metabolome of maize plants and the performance of the caterpillars, increasing knowledge on the biosynthesis and signaling pathways of JA, which will not only be important for developing insect-resistant lines of maize, but will elucidate the ancient history of the split between monocots and dicots.

My Experience

This internship gave me the hands-on research opportunity I had been wanting. Because my mentor taught me each step and the science behind the step for every procedure I learned, and then let me do the procedure on my own, I feel confident in my ability to work in any biology lab, regardless of concentration.

Another major take-away from this internship is an appreciation for the immense amount of work that goes behind each scientific publication. For example, prior to running an experiment, one must make sure each of the plants are the right genotype by conducting PCR, gel electrophoresis, and DNA sequencing. Then, during the experiment, researchers troubleshoot any errors that came up. Scientific research takes a lot of detail and patience, but it makes the result all the more rewarding.