Date: 11th October 2017
Title: Carbon for wood cell walls – new insights into the synthesis of cell wall polymers
Location: Biocentre 2, seminar room 2012, Viikinkaari 5
Host: Anna Kärkönen
Abstract: Forests assimilate approximately a quarter of the annual anthropogenic CO2 emissions. Most of this carbon is incorporated to wood which, together with the topsoil-bound carbon, creates the main long-term terrestrial carbon sink on the planet. The majority of the woody biomass, in which cellulose is the predominant constituent, resides in the cell walls of wood fibres. Carbon for the fiber walls is derived from sucrose, which is synthesized and transported from photosynthetic tissues. Sucrose is actively imported into developing wood fibers, and once in the cytosol sucrose hydrolysis is carried out either by invertase (INV) or sucrose synthase (SUS) activity to provide carbon and energy for cell wall biosynthesis. In this talk I will present our work on understanding the structure and regulation of the metabolic pathways responsible for carbon transport and incorporation into wood. This will include our recent finding placing the little studied cytosolic invertases in a central position in wood metabolism and cellulose biosynthesis, a concept of altering cellulose microfibril properties by modifying substrate supply to cellulose biosynthesis, and diurnal patterns of cell wall formation. I will also present recent results on cellulose biosynthesis in developing wood indicating that the model based on Arabidopsis results should not be generalized.
Totte graduated from the University of Helsinki in 2000 and moved to the John Innes Centre, UK where he did his PhD research on starch metabolism in the group of Prof Alison Smith. His PhD work led to the discovery of the plastidial maltose transporter and the importance of maltose as the main form of carbon exported from the chloroplasts at night. During this time, he also identified a novel phosphatase essential for starch degradation in leaves. After his PhD Totte carried out postdoctoral work as a HFSP and EMBO fellow in the group of Wolf Frommer at the Carnegie Institution of Science, California focusing on protein phosphorylation and sugar signal transduction using mass spectrometry based techniques. In 2009, he started his own group at the Umeå Plant Science Centre, Sweden and changed focus from Arabidopsis to trees. Totte is currently an associate professor at UPSC, and apart from research he is actively involved in the forest biotech company Swetree, as well as developing plant biology education at the Swedish University of Agricultural Sciences.