My early interest in biology grew during my time at high school in Manchester, England, and also made me realize the importance of applied aspects of the biological sciences. My undergraduate degree was in Plant Science in the Faculty of Agriculture at the University of Newcastle-upon-Tyne (England). During my third (final) year at Newcastle I became interested in carbon metabolism in plants (through a combination of undergraduate project work and interesting biochemistry lectures). I pursued my interest in plant carbon metabolism during my Ph.D. studies at University College of North Wales (Bangor), studying the physiological and biochemical aspects of plants infected by biotrophic fungal pathogens under the supervision of Dr. John F. Farrar. I moved back to my native city of Manchester to do post-doctoral work with Dr. Michael Emes, studying starch synthesis in plants, an area of research that I have continued with to this day. At Manchester, I developed methods for isolating the fragile organelles (amyloplasts) responsible for starch synthesis in storage tissues such as cereal endosperms and tubers. I also worked on characterizing plastidial metabolite transporters using liposome-based systems, in collaboration with Dr. Malcolm Jones (University of Manchester). Following post-doctoral studies, I was awarded a Leverhulme Special Research Fellowship, and studied the role of protein phosphorylation in the regulation of starch biosynthesis; at this stage, no role for this mode of regulation had been demonstrated for this pathway. In 2002 I moved to the University of Guelph (Department of Molecular and Cellular Biology).
- B.Sc. University of Newcastle-upon-Tyne
- Ph.D. University College of North Wales (Bangor)
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.
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) of the model plant Arabidopsis thaliana, 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. 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.
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 many collaborations with scientists in academia and in the food and non-food industries around the globe, as evidenced in my publication record.
Related projects also include work on human glycogen storage diseases in collaboration with Dr. Berge Minassian (Hospital for Sick Children, University of Toronto).
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 (International Rice Research Institute, Philippines). My research in starch metabolism is currently funded by OMAFRA, and NSERC.
Publications (past four years)
Chapters and Reviews
- Patterson, J. A., Emes, M. J., and Tetlow, I. J. (2017). Seed Development: Starch Synthesis. Thomas, Murray & Murphy (eds.). Encyclopedia of Applied Plant Sciences, Second Edition. Oxford: Elsevier (In Press).
- Tetlow, I.J., Liu, F., and Emes, M.J. (2015). Protein-protein interactions during starch biosynthesis. In: Starch Metabolism and Structure (ed. Nakamura, Y.), Chapter 9 (Springer).
- Tetlow, I.J., and Emes, M.J. (2014) A Review of Starch Branching Enzymes and their role in amylopectin biosynthesis. IUBMB Life 66 (8), 546-558.
- Tetlow, I.J. (2012). Branching enzymes and their role in determining structural and functional properties of polyglucans. In: Starch, origins, structure and metabolism (ed. Tetlow, I.J.), SEB Essential Review Series, Vol. 5, pp. 141-178. Society for Experimental Biology.
- Emes, M.J. and Tetlow, I.J. (2012) The role of heteromeric protein complexes in starch synthesis. In: Starch, origins, structure and metabolism (ed. Tetlow, I.J.), SEB Essential Review Series, Vol. 5, pp. 255-278. Society for Experimental Biology.
- Goldstein, A., Annor, G., Vamadevan, V., Tetlow, I.J., Kirkensgaard, J.J.K., Mortensen, K., Blennow, A., Hebelstrup, K. H., Bertoft, E. (2017). The influence of diurnal photosynthetic activity on the morphology, structure, and thermal properties of normal and waxy barley starch. International Journal of Biological Macromolecules 98, 188-200.
- Zhao, Q., Liu, F., Allan, W., Tetlow, I.J., Wattebled, F., D'Hulst, C., and Emes, M.J. (2017). Starch branching enzymes from Arabidopsis leaf chloroplasts are regulated by protein phosphorylation and can form heteromeric complexes with starch synthases. Journal of Experimental Botany (in press).
- Ahmed, Z., Tetlow, I.J., Falk, D., Liu, Q., and Emes, M.J. (2016) Resistant starch content is related to granule size in barley. Cereal Chemistry 93, 618-630.
- Boyer, L., Roussel, X., Courseaux, A., Ndjindji, O. F., Lancelon-Pin, C., Putaux, J.-L., Tetlow, I.J., Emes, M.J., Pontoire, B., D'Hulst, C., and Wattebled, F. (2016). Expression of E. coli glycogen branching enzyme in an Arabidopsis mutant devoid of endogenous starch branching enzymes induces the synthesis of starch-like polyglucans. Plant Cell and Environment 39 (7), 1432-1447.
- Liu, F., Zhao, Q., Mano, N., Ahmed, Z., Cai, Y., Chapman, K.D., Nitschke, F., Steup, M., Tetlow, I.J., and Emes, M.J. (2016). Modification of starch metabolism in transgenic Arabidopsis thaliana increases plant biomass and triples oilseed production. Plant Biotechnology Journal 14, 976-985.
- Peymanpour,G., Marcone, M., Ragaee, S., Tetlow, I.J., Lane, C.C., Seetharaman, K., and Bertoft, E. (2016). On the molecular structure of the amylopectin fraction isolated from ae maize starches. International Journal of Biological Macromolecules 91, 768-777.
- Luo, J., Ahmed, R., Kosar-Hashemi, B., Larroque, O., Butardo, V.M., Tanner, G.J., Colgrave, M.L., Upadhyaya, N.M., Tetlow, I.J., Emes, M.J., Millar, A., Jobling, S.A., Morell, M.K., and Li, Z. (2015). The different effects of starch synthase IIa mutations or variation on endosperm amylose content of barley, wheat and rice are determined by the distribution of starch synthase I and starch branching enzyme IIb between starch granule and amyloplast stroma. Theoretical and Applied Genetics 128 (7), 1407-1419.
- Crofts, N., Abe, N., Oitome, N.F., Matsushima, R., Tetlow, I.J.,Emes, M.J.,Nakamura, Y., and Fujita, N. (2015). Amylopectin biosynthetic enzymes from rice developing seed form enzymatically active protein complexes. Journal of Experimental Botany (in press).
- Ahmed, Z., Tetlow, I.J., Ahmed, R., Morell, M.K., and Emes, M.J. (2015) Protein-protein interactions among enzymes of starch biosynthesis in high-amylose barley genotypes reveal differential roles of heteromeric enzyme complexes in the synthesis of A and B granules. Plant Science 233, 95-106.
- Zhu, F., Bertoft, E., Wang, Y., Emes, M.J., Tetlow, I.J., and Seetharaman, K. (2015) Impact of diurnal cycle on structure of Arabidopsis leaf starch. Carbohydrate Polymers 117, 1002-1013.
- Richard Cisek, R., Tokarz, D., Steup, M., Tetlow, I.J., Emes, M.J., Hebelstrup, K.H., Blennow, A., and Barzda, V. (2015). Second harmonic generation microscopy investigation of the crystalline ultrastructure of three barley starch lines affected by hydration. Biomedical Optics Express 6 (10), 3694-3700.
- Cisek, R., Tokarz, D., Krouglov, S., Steup, M., Emes, M.J., Tetlow, I.J., and Barzda, V. (2014). Second harmonic generation from aligned water in starch granules. The Journal of Physical Chemistry B 118, 14785-14794. .
- Ahmed, N., Tetlow, I.J., Nawaz, S., Iqbal, A., Mubin, M., Rehman, S., Butt, A., Lightfoot, D.A., and Maekawa, M. (2015). Effect of high temperature on grain filling period, yield, amylose content and activity of starch biosynthesis enzymes in endosperm of basmati rice. Journal of the Science of Food and Agriculture 95, 2237-2243.
- Subasinghe, R., Liu, F., Polack, U., Emes, M.J., and Tetlow, I.J. (2014). Multimeric states of starch phosphorylase determine protein-protein interactions with starch biosynthetic enzymes in maize endosperm amyloplasts. Plant Physiology and Biochemistry 83, 168-179.
- Makhmoudova, A., Williams, D., Brewer, D., Massey, S., Patterson, J., Silva, A., Vassall, K.A., Liu, F., Subedi, S., Harauz, G., Michael Siu, K.W., Tetlow, I.J., and Emes, M.J. (2014). Identification of multiple phosphorylation sites on maize endosperm starch branching enzyme IIb, a key enzyme in amylopectin biosynthesis. Journal of Biological Chemistry 289, 9233-9246.
- Kalinga, D.N., Bertoft, E., Tetlow, I.J., Liu, Q., Yada, R.Y., and Seetharaman, K. (2014) Evolution of amylopectin structure in developing wheat endosperm starch. Carbohydrate Polymers 112, 316-324.
- Kalinga, D.N., Bertoft, E., Tetlow, I.J., and Seetharaman, K. (2014) Structure of clusters and building blocks in amylopectin from developing wheat endosperm. Carbohydrate Polymers 112, 325-333.
- MacNeil, S., Rebry, R.M., Tetlow, I.J., Emes, M.J., McKeown, B., and Graham, T.E. (2013) Resistant starch intake at breakfast affects postprandial responses in type 2 diabetics and enhances the glucose-dependent insulinotropic polypeptide-insulin relationship following a second meal. Applied Physiology, Nutrition and Metabolism 38, 1187-1195.
- Liu, F., Ahmed, Z., Lee, E.A., Weber, E., Liu, Q., Ahmed, R., Morell, M.K., Emes, M.J., and Tetlow, I.J. (2012) Allelic variants of the amylose extender mutation of maize demonstrate phenotypic variation in starch structure resulting from modified protein-protein interactions Journal of Experimental Botany 63, 1167-1183.
- Butardo, V.M., Daygon, V.D., Colgrave, M.L., Campbell, P.M., Ressureccion, A., Cuevas, R.P., Jobling, S., Rahman, S., Tetlow, I., Morell, M., and Fitzgerald, M. (2012). Biomolecular analyses of starch and starch granule proteins in the high amylose rice mutant Goami 2. Journal of Agricultural and Food Chemistry 60, 11576-85.
- Liu F., Romanova N., Lee, E.A., Ahmed, R., Evans, M., Gilbert, E.P., Morell, M.K., Emes, M.J., and Tetlow, I.J. (2012). Glucan affinity of starch synthase IIa determines binding of starch synthase I and starch branching enzyme IIb to starch granules. Biochemical Journal 448, 373-387.
- BOT2100 Life Strategies of Plants
- MCB*6350 Advanced Topics in Plant Biology
- Jessica White (Ph.D.)
- Liliya Nasanovsky (Ph.D.)
- Asena Goren (MSc)#
- You Wang (Ph.D.)*
- Jenelle Patterson (Ph.D.)*
- Greg MacNeill (Ph.D.)*
- Fatemeh (Sahar) Mehrpooyan (Ph.D.)*
# Co-supervised with Dr. Daniel Ashlock (Maths and Stats)
* Co-supervised with Dr. Michael Emes