Photochemistry of PSII in CYP38 Arabidopsis thaliana Deletion Mutant
Hrvoje Lepeduš1, Ana Tomašić2, Snježana Jurić2, Zorana Katanić3, Vera Cesar3 and Hrvoje Fulgosi2*
1Agricultural Institute Osijek, Južno predgrađe 17, HR-31000 Osijek, Croatia
2Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia
3Department of Biology, University of J.J. Strossmayer in Osijek, Trg Lj. Gaja 6, HR-31000 Osijek, Croatia
Article history:
Received October 30, 2008
Accepted March 31, 2009
Key words:
chlorophyll fluorescence, photosystem II, photosynthesis regulation, OJIP test, TLP40
Summary:
Chloroplast protein CYP38 is a cyclophilin-like peptidyl-prolyl cis-trans isomerase involved in photosystem II (PSII) assembly. It also serves as a regulator of thylakoid protein phosphatase. In this work the efficiency of PSII in CYP38 deficient Arabidopsis thaliana M13 plants has been analyzed by measuring in vivo chlorophyll a (Chl a) fluorescence transient (OJIP test). Significant differences in overall photosynthetic performance (PIABS), absorption (ABS/RC), trapping (TRo/RC), electron transport (ETo/RC), and dissipation (DIo/RC) were observed between A. thaliana M13 and the wild type (WT) plants. Increased Chl a and Chl b levels, as well as decreased Chl a/Chl b ratio were measured in M13 plants, indicating the adjustment of PSII antenna for increasing light absorption capability. Based on the obtained results, it can be concluded that the deficiency in CYP38 protein leads to impaired function of PSII due to the conversion of a certain fraction of active reaction centres to dissipative ones. This leads to a decrease in overall photosynthetic performance (PIABS) in M13 plants. Such effect was due to lowering of TRo/DIo parameter, which was influenced mostly by significant increases in energy dissipation (DIo/RC) and in trapping of electrons (TRo/RC) per active reaction centre.
*Corresponding author: 
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