“Investigating the activation/deactivation mechanisms of jasmonate signaling in maize (Zea mays)”

 Project Summary:

The jasmonate signaling pathway controls many plant processes, including growth, development, and defense. One key component in this pathway is the fatty acid derivative jasmonic acid (JA). JA is induced by both abiotic and biotic stresses such as mechanical wounding and herbivory. Upon induction, JA is converted into its bioactive form JA-isoleucine (JA-Ile), which is perceived by its F-box COI1 receptor. JA-Ile perception results in a wide transcriptional reprogramming activating the immune system of the plant. This process is costly; therefore, plants need to maintain a fine-tuned homeostasis to optimize fitness and guarantee survival. In Arabidopsis thaliana, JA conjugation/deconjugation to Ile is achieved by amido-synthases/-hydrolases of the GH3 superfamily, respectively. A phylogenetic analysis of GH3 proteins revealed two candidate genes for conjugation and deconjugation of JA to Ile in maize. The objective of the work was to understand the role of the identified enzymes, JIH1 and IAA-AS, in regulating the jasmonate signaling pathway in Zea mays (maize). To achieve this goal, two experiments were conducted, (i) quantification jasmonate content on mutant lines, and (ii) a caterpillar performance assay on the same set of plants. The data showed the absence of JIH1 did not have a clear impact on maize defense against the generalist insect Spodoptera exigua. Results obtained with IAA-AS were inconsistent and further studies are needed to assess the role of this enzyme in maize. Future studies should be conducted on the activity of IAA-AS by employing different mutant lines than those analyzed in this study. Additionally, it may be helpful to find other metabolites that are impacted by these enzymes through an untargeted metabolomic analysis.

My Experience:

The past few weeks in the Jander lab have been an eye-opening experience. Being immersed in an environment with passionate researchers has exposed me to the vastness of plant biology research, a truly humbling experience. Working with my mentor, Dr. Jimenez-Aleman, I was able to get a glimpse of how to approach certain problems, not only with the available technology but also in the most efficient way. Caterpillar performance assays, phytohormone extraction, and running and analyzing samples via UPLC-MS/MS are just some of the techniques that I learned for my project. Along with learning new approaches and lab techniques, I was able to gain confidence with previously learned lab techniques, which has helped me to develop into a better scientific researcher. I will take all of these acquired techniques, approaches, and skills to my home institution, where I will continue to investigate key enzymes in the jasmonic acid signaling pathway in maize.