Cold-acclimation protects photosystem II against freezing damage in the halotolerant alga XXXX .

@entity26 @entity6618 @entity653
Cold-acclimation (CA) of the halotolerant alga @entity6618 was inhibited by light and by high salt. CA was associated with enhanced resistance to freezing in saline growth solutions, as manifested by protection of photosynthetic @entity26 evolution and by reduced permeabilisation of the plasma membrane. @entity26 evolution activity in isolated chloroplasts was not affected by freezing, but was inhibited by high salt and the inhibition could be reversed or protected by @entity653 . The activity of chloroplasts from cold-acclimated cells was more resistant to salt than of non-acclimated cells. Electron transport measurements in chloroplasts indicated that high salt inhibited PS-II, but not PS-I electron transport. High salt also inhibited PS-II thermoluminescence (TL) activity in chloroplasts. Similar inhibition of PS-II TL was observed by freezing intact cells in saline solutions. Chloroplasts from cold-acclimated cells had enhanced resistance to inhibition of PS-II electron transport and of PS-II TL by high salt. These results suggest that inhibition of @entity26 evolution upon freezing @entity6618 cells may result from inactivation of PS-II due to massive influx of salt and loss of @entity653 . The enhanced freeze-resistance of cold-acclimated cells to inhibition of @entity26 evolution can be accounted for partly by protection of PS-II against high salt.
