Assistant Research Professor
Ph.D. 1995, Kyungpook National University, South Korea
Starch is the major energy reserve in most plants. A portion of the photoassimilates generated by photosynthesis is converted into starch as a transitory intermediate in source (also transient sink) organs or as a stable final product in sink organs. Several enzymes play pivotal roles in the course of starch metabolism. The ultimate goal of this research is to significantly improve important agronomic parameters that impact plant productivity (biomass) by understanding and customizing specific enzymes in these processes. Our current research is focusing on the enzymes that directly control starch synthesis: ADP-glucose pyrophosphorylase and starch phosphorylase. Computational and biochemical approaches, such as structural modeling, mutagenesis, and kinetic analyses, have uncovered significant insights on the roles of the two AGPase subunits in enzyme’s regulation and catalysis. Several allosterically up-regulated AGPase mutants have been introduced into model plants (Arabidopsis and rice) and studies are undergoing to determine the relationship between enzymatic properties and starch synthesis/plant productivity. Starch phosphorylases (OsPHOL and OsPHOH) are also being studied as the candidates for further understanding of starch metabolism since recent results indicate that a mutation on the OsPHOL gene significantly reduced starch content in rice endosperm.