Figure 6. Acclimation, xanthophyll cycle and Non Photochemical Quenching in P. patens.

WT plants were grown for 3–5 days under control conditions and then acclimated for 10 days to four different light intensities: Low Light 5 µE m⁻² s⁻¹ (LL), Control Light 20 µE m⁻² s⁻¹ (CL), High Light 70 µE m⁻² s⁻¹ (HL) and Very High Light 500 µE m⁻² s⁻¹ (VHL). A) Morphology of Acclimated plants. B) Pigment composition of acclimated plants after an overnight (14 h) dark adaptation. Carotenoid content is expressed as moles/100 moles of Chl a+b. C) Carotenoid composition comparison between dark adapted samples and samples treated for two hours with their corresponding growth conditions. D) Comparison of Non Photochemical Quenching (NPQ) kinetics after an overnight dark adaptation for Physcomitrella (grown in control conditions for 12 days, solid, squares) and Arabidopsis grown for 6 weeks at 100 µE m⁻² s⁻¹ (dashed, circles). Measurements were performed with saturating light at 4500 µE m⁻² s⁻¹ (duration time 600 µs) and actinic light at 1200 µE m⁻² s⁻¹ (which was on only for the first 8 minutes).