Resistance of Antarctic moss Sanionia uncinata to photoinhibition: Chlorophyll fluorescence analysis of the samples from Western and Eastern coast of the Antarctic Peninsula.

Interspecific differences in the sensitivity of Antarctic moss Sanionia uncinata from the King George Island (KGI) and James Ross Island (JRI) to photoinhibititory treatment were studied in laboratory conditions by chlorophyll fluorescence techniques. Slow (Kautsky) and fast (OJIP) kinetics were used for the measurements. Samples were exposed to a short-term (60 min) photoinhibitory treatment (PIT, 2000 μmol m-2 s-1 of photosynthetically active radiation). The photoinhibitory treatment (PIT) led to photoinhibition which was indicated by the decrease in FV /FM and ΦPSII in the KGI but not JRI samples. The decrease was, however, low and full recovery was reached 90 minutes after the PIT termination. Non-photochemical quenching (NPQ) was activated during the PIT, and relaxed fast during recovery.. Early stages of photoinhibition showed the drop of FV /FM and ΦPSII to minimum values within the first 10 s of the PIT with their subsequent increase apparent within fast (0-5 min PIT) and slow phase (5-50 min PIT) of adjustment. The PIT caused the decrease of performance index (Pi_Abs), photosynthetic electron transport per reaction center (ET0 /RC (RC). The PIT induced an increase in thermal dissipation per RC (DI0 /RC), effectivity of thermal dissipation (Phi_D0 ), absorption per reaction center (ABS/RC), and trapping rate per RC (TR0 /RC). In conclusion, PIT led to only slight photoinhibition followed by fast recovery in S. uncinata from KGI and JRI since FV /FM and ΦPSII returned to pre-photoinhibitory. Therefore, S. uncinata might be considered photoinhibition resistant even in wet state. The KGI samples showed higher resistance to photoinhibition than JRI ones.