“Functional Analysis of a Putative UDP-Glycosyltransferase Involved in the Biosynthesis of Cardiac Glucosides in Erysimum cheiranthoides”
Cardiac glycosides are a class of defense-related plant metabolites that inhibit animal Na+, K+-ATPase membrane ion transporters, and thereby deter certain insect species from feeding or ovipositing on the plants that produce them. Despite their potential medical and agricultural applications, the biosynthetic pathway of cardiac glycosides remains incomplete to this day. Candidate genes were selected based on comparisons of 3′-RNA-seq and LC-MS analyses, performed before and after elicitation of defenses in Erysimum cheiranthoides (wormseed wallflower), a Brassicaceae species that is phylogenetically close to the model plant Arabidopsis thaliana. This identified a gene coding for a predicted UDP-glycosyltransferase that could catalyze the last step of the production of erycordine, a cardiac glycoside that was previously identified in E. cheiranthoides. Through cloning in plasmid vectors for over- or under-expression, then transformation via Agrobacterium tumefaciens and A. rhizogenes, the UDP-glycosyltransferase candidate gene was expressed transiently in the leaves and roots of E. cheiranthoides. LC-MS analysis of cardiac glycosides was performed to confirm whether or not there are effects on this metabolic pathway. In addition to obtaining the complete pathway of cardiac glucoside biosynthesis, the discovery of new molecules and the improvement of the methods for obtaining these compounds could be a significant asset for medical research. Moreover, cardiac glycoside biosynthesis could be used to protect crops and thus help reduce the use of pesticides.
Studying in the first year of a master’s degree in Plant Integrative Biology and Breeding in France, I had to do a two-month internship to complete my school year. By coming to the BTI, in addition to acquiring a first real professional experience in research laboratory, I took this opportunity in the United States to improve my English and gained many new laboratory techniques. I was also able to put to other techniques to use that I knew but I had never realized in application for. As the weeks went by, I gained more and more confidence in the manipulations and I began to really appreciate the research work, even with the few moments of frustration when the results were not what I expected. Apart from my research topic, participating in the PGRP also allowed me to discover a range of new plant biology research topics by attending the various seminars and becoming friends with the other students in the program. The bioinformatics courses offered have also improved my understanding of the methods used to obtain candidate genes. Before spending my summer in Ithaca, I wasn’t very motivated to continue my studies and obtain a PhD, but it is now a career path that I am considering more seriously.