Changes in net photosynthesis, chlorophyll fluorescence and xanthophyll cycle interconversions during freeze-thaw cycles in the Mediterranean moss Leucodon sciuroides.

The tolerance to freezing and thawing of Leucodon sciuroides, a moss growing in mountainous areas of the Mediterranean (south-east Spain), was investigated by means of CO gas exchange, modulated chlorophyll (Chl) a fluorescence and pigment analysis by high-performance liquid chromatography. Evidence is presented for freezing-induced decreases in CO fixation that enhance non-radiative dissipation of absorbed light energy, a process which protects the photosynthetic apparatus. The photosynthetic apparatus of L.