Photoprotection in oxygenic photosynthesis: A reverse genetic study

Light is essential for photosynthesis and life on earth and yet it is harmful for plants. When photons are absorbed in excess with respect to the capacity of photosynthetic electron transport, reactive oxygen species are produced that causes photoinhibition, limiting plant growth and productivity. Oxygenic photosynthetic organisms have evolved photoprotective mechanisms to prevent/avoid photodamage. Among these, the Non-Photochemical Quenching (of chlorophyll fluorescence) or NPQ is of particular interest. NPQ has been reported to quench the chlorophyll excited states thus catalyzing the thermal dissipation of energy absorbed in excess. Over the past decades many efforts have been made to elucidate the mechanisms underlying these processes. Besides academic curiosity, manipulation of thermal dissipation rate and its regulation in response to environmental cues appears to be the key for both enhancing stress resistance and productivity for food and fuels. In my PhD I used a reverse genetic approach on the model organism Arabidopsis thaliana to disentangle and characterize the role of different components of photoprotective mechanisms as well as their contribution to acclimation to abiotic stresses. Of particular interest have been the generation and analysis of mutants defective in carotenoids biosynthesis, specific xanthophyll binding proteins and in the chloroplast light avoidance mechanism.