Current Research
An underlying aim throughout my research career has been to understand how plant metabolism is regulated; and in particular, how carbohydrate metabolism in plastids is regulated. One of the unique aspects of plant cell biology is the compartmentalization of certain metabolic pathways within specialized sub-cellular organelles termed plastids. The origin of plastids is thought to be traced back in time to the ingestion of a photosynthetic cyanobacterial cell by an ancient plastid-less protist, and its eventual transformation into a plastid. Many of the world’s most important agricultural products (e.g. starches and oils) are made inside plastids, and the central theme of my research interests has been the study of these important organelles.
The major research topics currently being pursued in my laboratory are summarized below.
Research Topics
1. Regulation of Starch Biosynthesis in Higher Plants
Broadly, this involves examining the control mechanisms underpinning starch biosynthesis in leaf chloroplasts (which make starch during the daytime, and degrade it at night) and non-photosynthetic amyloplasts of cereal endosperms such as maize, wheat, barley and rice which make storage starches. More specifically, we are interested in the biochemical control mechanisms governing the many enzymes and enzyme classes which make up the core pathway of starch biosynthesis [Fig.1]. This involves investigating the role of protein-protein interactions and protein phosphorylation in coordinating the proteins involved in starch synthesis and degradation within the plastid to produce the highly ordered and complex structure of the starch granule [Fig.2].
Addressing these fundamental scientific questions has potentially important applied benefits, enabling us to make more rational attempts at yield improvement in crops, and design starch structures which are suited to particular end-users, e.g. starches for the food industry with improved human health benefits, or starches for the non-food sector (e.g. paints and coatings). Consequently, this research has led to a number of collaborations with scientists in the food and non-food industries.
Related projects include work on human glycogen storage diseases in collaboration with Dr. Berge Minassian (Hospital for Sick Children, University of Toronto), and I am a member of the BioCar project, a multidisciplinary team involved in delivering biomaterials for the automotive industry.
The various projects related to understanding starch metabolism are part of a close, long-standing collaboration with Dr. Michael Emes (Dean of CBS, and faculty member of MCB) and Dr. Matthew Morell (Theme Leader, Food Futures Flagship, CSIRO Plant Industry, Canberra). My research in starch metabolism is currently funded by OMAFRA, NSERC, CFI and ABIP grants.
2. Regulation of Tocopherol (Vitamin E) Biosynthesis in Plants
Tocopherols and tocotrienols are an important group of lipid-soluble antioxidants synthesized exclusively in photosynthetic tissues, with many beneficial properties, both with respect to human health (e.g. vitamin E activity), and within the food industry. We are taking a multi-disciplinary approach to understanding the regulation and organization of tocopherol and tocotrienol biosynthesis both in leaf chloroplasts of Arabidopsis (a model plant system) and photo-heterotrophic plastids of developing oilseeds such as soybean. In particular, the sub-organellar organization of the pathway is being examined, and its relationship to other metabolic pathways and factors or elements of signal transduction cascades and intra-plastidial trafficking systems. This research will provide important insights into the mechanisms governing the control and regulation of important metabolic pathways in the plastids of higher plants, and contribute to engineering crops with improved nutritional value and enhanced high-value bioproducts. This research is funded by NSERC and ABIP grants.
