UV-B induced alteration of oxygen evolving reactions in pea thylakoid membranes as affected by scavengers of reactive oxygen species

作者：Lazarova D; Stanoeva D; Popova A; Vasilev D; Velitchkova M^*

来源：Biologia Plantarum, 2014, 58(2): 319-327.

DOI：10.1007/s10535-014-0402-0

• 77 K fluorescence
• DMSO
• flash oxygen yields
• histidine
• initial oxygen burst
• n-propyl gallate
• oxygen evolution
• Pisum sativum
• ROS

The effect of UV-B irradiation at temperatures of 22 and 4 A degrees C on flash induced oxygen yields, photochemical activity, and energy transfer in pea thylakoid membranes in the absence and presence of scavengers of reactive oxygen species (ROS) was studied. Three different scavengers were used: dimethyl sulfoxide (DMSO), histidine (His), and n-propyl gallate (nPG). As result of the UV-B treatment of isolated membranes, the flash oxygen yields were considerably affected - the amplitudes decreased and the oscillation pattern was lost. The analysis of the flash oxygen yields and initial oxygen burst showed alterations of a number of oxygen evolving centers in the S0 state as well as changes of decay kinetics of the oxygen burst under continuous irradiation. ROS scavengers exhibited more or less expressed protective effects, nPG being the most effective against UV-B induced damages of the flash oxygen yields. At both the temperatures, photosystem II (PS II) mediated electron transport was more sensitive to the UV-B treatment in comparison with photosystem I (PS I). The analysis of 77 K fluorescence spectra showed that the fluorescence ratio F735/F685 increased by the UV-B treatment probably due to a redistribution of excitation energy between both photosystems most likely caused by partial unstacking and due to a decrease of PS II fluorescence resulting from reaction center-type quenching. The nPG was the most powerful scavenger which protected the oxygen evolution capacity of PS II in the absence and presence of an exogenous electron acceptor to the highest extent.

• 出版日期2014-6