Kinetic Analysis of Carbon-11-Labeled Carbon Dioxide for Studying Photosynthesis in a Leaf Using Positron Emitting Tracer Imaging System

Abstract

The positron emitting tracer imaging system (PETIS) and carbon-11-labeled carbon dioxide (¹¹CO₂) can be used for imaging the photosynthesis process in plant leaves. Further, ¹¹C kinetics facilitate the estimation of the physiological function parameters of photosynthesis. PETIS measurements were performed under four light conditions for each exposure of a single leaf to ¹¹CO₂ gas. In order to estimate the rate constants of the photosynthesis parameters, the time-activity curves of the input ¹¹CO₂ gas and the leaf response were fitted to an appropriate compartmental tracer kinetic model that considers photoassimilation and sucrose export rate constants as influx and efflux, respectively. The data obtained by this method show a reasonable response with respect to the photoenvironment of the leaf, and they are important for discussing photosynthesis with regard to plant physiology and agriculture