Undergraduate Hsin-Yu "Lucy" Chen was awarded the best poster prize last April 5 at the UTM undergaduate poster session. Along with several other undergraduates, including Alex Chang, Ekaterina "Kate" Kibkalo, Lana Sobh, Ibadat Bajwa, and Haniya Adnan, Lucy represented the Phillips lab by presenting original research.
Lucy began as a volunteer in the lab and took on an independent project last January. After a summer hiatus for travel, she will return to the Phillips lab this fall to continue work on this project as an undergraduate thesis student.
Her work deals with the origin of pyruvate in the chloroplasts of higher plants. Long a metabolic mystery, pyruvate needed in chloroplasts is thought to derive from phosphoenolpyruvate in the cytosol due to two steps of glycolysis that are downregulated in chloroplasts (glycolysis is active both in plastids and in the cytosol of most plant cells and supplies pyruvate when the pathway is fully functional). This downregulation in photosynthetic plastids (chloroplasts) is thought to be an adaptation which avoids conflicts over common substrates between some reactions of the Calvin-Benson cycle and these downregulated steps of glycolysis. But since plastids still need large quantities of pyruvate as a starting point for several biosynthetic pathways, it is thought to be imported from the cytosol as phosphoenolpyruvate. We asked what would happen if we restored these potentially conflictive steps to gain some insight into where these pyruvate equivalents really come from and why nature chose this roundabout pathway of pyruvate trafficking during the course of evolution. Can plants with fully functional glycolytic pathways in photosynthetic tissue still grow, and if so what do their isoprenoid and lipid profiles look like (both require pyruvate for their synthesis)? This issue has been partially addressed by a German group at the University of Cologne several years ago (Prabhakar et al 2010 Plant Cell) but the larger issues of carbon flux and impact on plastid-specific metabolism were never fully answered. Lucy's work provides us with the genetic resources to conduct whole plant labeling experiments on transgenic lines modified to reveal the details of pyruvate traffic in the plant cell. The next experiments should be highly revealing. A hearty congratulations to Lucy for her well deserved award. May there be many more!