Seminar, 08. September 2016, Johann Rohwer

08. September 2016, 16:15 p.m.

Ernst-Abbe-Platz 2, seminar room 3423

Kinetic modelling as a tool for understanding and manipulating plant metabolism: the case of sucrose accumulation in sugarcane

Prof. Dr. Johann M. Rohwer
(Laboratory for Molecular Systems Biology, Department of Biochemistry, Stellenbosch University, 7600 Stellenbosch, South Africa
Present address: Department of Biochemistry, Max Planck Institute for Chemical Ecology, 07745 Jena, Germany)

Significant changes occur in sucrose metabolism when moving from immature to mature internodal tissue in sugarcane. In general, sucrose accumulation increases, while growth slows down. To understand all these processes is of central importance, both from a fundamental biochemical point of view and with agro-biotechnological applications in mind. As part of a rational enhancement strategy, we have developed a kinetic model to simulate sucrose metabolism in the sugarcane stalk. The initial model, based on medium-mature sugarcane tissue (internode 5) predicted a number of strategies for increasing sucrose production, such as the knock-down of cytosolic neutral invertase. Subsequently, the model was extended to simulate internodes 3-10 of a sugarcane stalk by modelling growth changes through substitution of internode-specific parameters. Although this model could capture some of the physiological changes during sugarcane stalk maturation, it suffered from the limitation that movement of solute between internodes was not captured. To overcome this, a more integrated model of sucrose accumulation based on partial differential equations was developed, allowing us to model all eight internodes at the same time. The model spans five compartments, the source, phloem, apoplast, symplast and vacuole. Sucrose translocation in the phloem is modelled explicitly, providing a bridge between internodes. The present model provides a comprehensive description of sucrose accumulation and is a rigorous, quantitative framework for future modelling and experimental design.