Visualization of dynamics in woody tissue photosynthesis via positron autoradiography of xylem-transported 11CO2 (Jens Mincke)
Jens Mincke obtained his MSc in Chemistry and Bioprocess Technology at Ghent University in 2013 and obtained a second MSc in Biomedical Engineering at Ghent University & Vrije Universiteit Brussel in 2015. Jens is currently conducting PhD research under the supervision of Prof. Dr. ir. Kathy Steppe (research group: Laboratory of Plant Ecology) and Prof. Dr. Stefaan Vandenberghe (research group: Medical Imaging and Signal Processing) at Ghent University. His research focuses on tracing radioactive molecules in xylem of plants to quantify the contribution of internally transported CO2 to the total carbon budget. This locally respired internal CO2 is substantially higher in concentration (26%) than the atmospheric CO2 concentration (± 0,04%). It is known that a portion of this CO2 escapes into the atmosphere during transport and that photosynthetic active cells in stem or leaves can fix another portion. A new approach for direct visualization of woody tissue (stem) photosynthesis has been developed and implies the use of a radioactive [11C]-tracer. To this end, a cut branch is put in an aqueous solution containing dissolved 11C-labelled CO2 molecules. Uptake and transpiration of the enriched solution is triggered by illumination of the branch with light emitting diodes, which is also necessary for (stem) photosynthesis to occur. Afterwards, autoradiography is performed to detect the location and distribution of radioactivity inside the branch. Dynamics in woody tissue photosynthesis were investigated using different treatments, including wrapping of aluminium foil to exclude photosynthetically active radiation from reaching a section of the branch. In addition, a similar treatment with dissolved [18F]fluorine was applied to investigate water transport. Experiments were conducted on young branches of poplar, a species in which CO2 refixation has been reported. Results demonstrated that woody tissue photosynthesis is a very dynamic process in young woody plants, implying that sap flow is not only important for understanding the water relations in plants, but also contributes to the carbon balance. Therefore, green stem tissues are important for the functioning of plants, and may be more important than previously thought under dry conditions.
Jens Mincke won an ISHS student award for the best oral presentation at the X International Workshop on Sap Flow in USA in May 2017.
Jens Mincke, Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Coupure Links 653, Ghent University, Belgium, e-mail: Jens.Mincke@UGent.be
The full article is available in Chronica Horticulturae