Measurement of gross photosynthesis, respiration in the light, and mesophyll conductance using H218O labeling (Plant Physiol)

It is relatively simple to determine net O₂ flux in leaves.  However, this data provides no information on the underlying processes responsible for this flux, namely gross oxygen production (GOP, water splitting), mitochondrial respiration in light, Rubisco oxygenation, and photorespiration.  In this ‘Breakthrough Technologies’ paper, Gauthier et al outline a method that utilises H₂¹⁸O labelling to precisely measure both net oxygen production (NOP) and GOP for detached leaves.  This was performed in a chamber with regulated temperature and humidity, and conventional CO₂ and light response curves were performed simultaneously.  As a proof of concept, the authors used this technique to determine O₂ metabolism in leaves of Phaseolus vulgaris, and examined both the light response of mesophyll CO₂ conductance and the Kok effect.  (Summary by Mike Page) Plant Physiol 10.1104/pp.16.00741