Novel methodology for quantitative assessment of the capacity for photoprotection in photosynthetic organisms

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The dissipation of excess excitation energy (NPQ) in the photosynthetic membrane is a fundamental process that prevents damage to the photosynthetic membrane, particularly oxygen-evolving photosystem II reaction centers. However, exploiting NPQ for quantitative assessment, the prediction of plant wellbeing and for the possible improvement of photosynthesis has not occurred, partly due to a lack of knowledge concerning the nature and amplitude of the photoprotective component of NPQ (pNPQ) and its optimal level required for photosynthesis. Indeed, we urgently need methods that routinely separate components of NPQ that are crucially important from those not essential or even detrimental for plant survival and productivity. Here we propose to develop and test innovative, non-destructive and effective fluorescence techniques to isolate the beneficial (protective) component of NPQ in vivo and to determine its optimal level via generation of a number of quantitative parameters of light tolerance. We will use molecular and physiological approaches to apply these methods to leaf photosynthesis of a model plant species, Arabidopsis thaliana, and its various mutants. We will determine the impact of all NPQ components, photoprotective and photoinhibitory, on the state of the PSII reaction centers, electron transport, growth rate and biomass production and using mutant plants we will identify new targets for the forecasting and improvement of light energy utilization, stress resistance and overall plant wellbeing.