Effects of sub-optimal illumination in plants. Comprehensive chlorophyll fluorescence analysis

TORRES, R.; ROMERO, J.M.; LAGORIO, M.G.

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY

ELSEVIER SCIENCE SA

Año: 2021 vol. 218

1011-1344

The fluorescence signals emitted by chlorophyll molecules of plants is a promising non-destructive indicator ofplant physiology due to its close link to photosynthesis. In this work, a deep photophysical study of chlorophyllfluorescence was provided, to assess the sub-optimal illumination effects on three plant species: L. sativa,A. hybridus and S. dendroideum. In all the cases, low light (LL) treatment induced an increase in pigment content.Fluorescence ratios ? corrected by light reabsorption processes ? remained constant, which suggested thatphotosystems stoichiometry was conserved. For all species and treatments, quantum yields of photophysicaldecay remained around 0.2, which meant that the maximum possible photosynthesis efficiency was about 0.8.L. sativa (C3) acclimated to low light illumination, displayed a strong increase in the LHC size and a net decreasein the photosynthetic efficiency. A. hybridus (C4) was not appreciably stressed by the low light availabilitywhereas S. dendroideum (CAM), decreased its antenna and augmented the quantum yield of primary photochemistry.A novel approach to describe NPQ relaxation kinetics was also presented here and used to calculatetypical deactivation times and amplitudes for NPQ components. LL acclimated L. sativa presented a much largerdeactivation time for its state-transition-related quenching than the other species. Comprehensive fluorescenceanalysis allowed a deep study of the changes in the light-dependent reactions of photosynthesis upon low lightillumination treatment.