Abstract - Estimations of the gross primary productivity (GPP) of land ecosystems are key to accurately predict the global carbon cycle. The photosynthesis models underpinning these estimates are making simplifications that result in GPP inaccuracies in the order of 10-15% by the end of the century. These simplifications have been necessary due to insufficient understanding of how CO₂ is taken up by the leaf. Carbon isotopes are commonly used to study how CO₂ diffuses within photosynthetic plant tissues, information that is difficult to obtain with common gas exchange techniques alone. The standard model relating carbon isotope discrimination to physical and biochemical processes within the leaf often returns unreasonable results for mesophyll conductance to CO₂ diffusion. Here, I will discuss the impact of a re-derived carbon isotope discrimination model on quantifying mesophyll conductance and the implications this has for predictions of plant carbon uptake. This new model allows us now to assess how mesophyll conductance varies under changing environments. I will also outline a new theoretical framework that can be used to mechanistically implement mesophyll conductance into photosynthesis models, eventually giving us the opportunity to vastly improve global GPP estimates.

Biography - Florian Busch (University of Birmingham) is a theoretical and experimental plant physiologist interested in all aspects of photosynthesis. His focus is on linking different photosynthetic processes with mathematical models to study the biochemical limitations of carbon fixation and to gain a quantitative understanding of how plant carbon uptake responds to changes in the environment. Florian obtained his PhD in 2008 from the Heinrich-Heine University in Düsseldorf, Germany, during which time he worked closely with Norm Hüner at Western University in London, Canada. After several years of post-doctoral work with Rowan Sage at the University of Toronto, Canada he moved to the Australian National University to first work as a Postdoctoral Fellow with Susanne von Caemmerer and later as a Research Fellow with Graham Farquhar. He is now an Associate Professor in the School of Biosciences at the University of Birmingham.

Website:

https://www.birmingham.ac.uk/staff/profiles/biosciences/busch-florian