EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

The pigment antenna constraining the light reactions: photosynthetic energy redistribution indicated by leaf absorbance changes

Shari Van Wittenberghe1,2, Valero Laparra3, Nacho Ignacio Garcia4, Luis Alonso1, Beatriz Fernandez Marín5, Zbynek Malenovsky6, Albert Porcar-Castell2, and Jose Moreno1
Shari Van Wittenberghe et al.
  • 1University of Valencia, Laboratory of Earth Observation, Spain (
  • 2University of Helsinki, Optics of Photosynthesis Laboratory, Finland
  • 3University of Valencia, Image and Signal Processing Group, Image Processing Laboratory, Spain
  • 4University of the Basque Country, Department of Plant Biology and Ecology, Spain
  • 5University of La Laguna, Department of Botany, Ecology and Plant Physiology, Spain
  • 6University of Tasmania, Geography and Spatial Sciences, School of Technology, Environments and Design, Australia

The solar energy absorbed by the vegetation light-harvesting antenna complexes supplies the photosynthetic light reactions with a highly efficient transfer of quantum energy. The absorbed energy is efficiently transferred from one molecule to another, until being used by the reaction centres for the further carbon reactions. The energy transfer to the reaction centres is hereby highly regulated by the variable aggregation of pigments in the antenna complexes, allowing for quick and slower adjustments according to the incoming solar radiance. To control and protect the pigment antenna and the reaction centres from a potentially harmful solar radiance excess, these regulated photoprotective mechanisms are activated at different time scales at the antenna level, allowing vegetation to adapt to changing light conditions. The understanding of these energy regulative processes from optical measurements is essential in order to monitor plants' adaptation strategies to stressful environments and changing climates from remote sensing data.

Using high-spectral resolution leaf spectroscopy in a controlled laboratory set-up, we have observed detailed and significant absorbance shifts controlled by the pigment antennas themselves. Simultaneous measurements of both upward and downward spectrally-resolved leaf radiance (Lup(λ), Ldw(λ), W m-2 sr-1 nm-1) allowed us to observe the specific absorbance changes at leaf level, including changes in chlorophyll (Chl) a fluorescence emission (Fup(λ), Fdw(λ), W m-2 sr-1 nm-1). Interestingly, these changes due to shifts in energy redistribution were: 1) observed in the PAR region and even far beyond 700 nm, and 2) indicated a prominent role of both Carotenoid and Chl a molecules in the creation of alternative energy sinks, i.e. constraining the energy transfer to the reaction centres. Hereby, a significant redistribution of photosynthetic light energy was observed in the 500-800 nm range, highlighting this spectral region to be of potential interest for remote sensing. We further revealed that these energy redistributions do not necessary occur in parallel with Chl a fluorescence changes, illustrating the importance of different energy redistribution mechanisms constraining the photosynthetic light reactions. To conclude, a good quantitative understanding of all mechanisms of energy regulation in plants based on VIS-NIR wavelengths is essential 1) to be able to understand these trends using remote sensing data, 2) to better model the adaptations of vegetation to changing climate and environmental conditions, and 3) potentially better predict future trends in dynamic global vegetation models.

How to cite: Van Wittenberghe, S., Laparra, V., Ignacio Garcia, N., Alonso, L., Fernandez Marín, B., Malenovsky, Z., Porcar-Castell, A., and Moreno, J.: The pigment antenna constraining the light reactions: photosynthetic energy redistribution indicated by leaf absorbance changes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9713,, 2020


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