Kinetics of the Xanthophyll Cycle and its Role in the Photoprotective Memory and Response

Kavli Affiliate: Graham R. Fleming

| First 5 Authors: Audrey Short, Thomas P. Fay, Thien Crisanto, Ratul Mangal, Krishna K. Niyogi

| Summary:

Efficiently balancing photochemistry and photoprotection is crucial for
survival and productivity of photosynthetic organisms in the rapidly
fluctuating light levels found in natural environments. The ability to respond
quickly to sudden changes in light level is clearly advantageous. In the alga
Nannochloropsis oceanica we observed an ability to respond rapidly to sudden
increases in light level which occur soon after a previous high-light exposure.
This ability implies a kind of memory. In this work, we explore the xanthophyll
cycle in N. oceanica as a photoprotective memory system. By combining snapshot
fluorescence lifetime measurements with a biochemistry-based quantitative model
we show that both short-term and medium-term "memory" arises from the
xanthophyll cycle. In addition, the model enables us to characterize the
relative quenching abilities of the three xanthophyll cycle components. Given
the ubiquity of the xanthophyll cycle in photosynthetic organisms the model
described here will be of utility in improving our understanding of vascular
plant photoprotection with important implications for crop productivity.

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