Light quality significantly influences plant metabolism, growth and development. Recently, we have demonstrated that leaves of barley and other plant species grown under monochromatic green light (500-590 nm) accumulated a large pool of chlorophyll a (Chl a) intermediates with incomplete hydrogenation of their phytyl chains. In this work, we studied accumulation of these geranylgeranylated Chls a and b in pigment-protein complexes (PPCs) of Arabidopsis plants acclimated to green light and their structural-functional consequences on the photosynthetic apparatus. We found that geranylgeranylated Chls are present in all major PPCs, although their presence was more pronounced in light-harvesting complex II (LHCII) and less prominent in supercomplexes of photosystem II (PSII). Accumulation of geranylgeranylated Chls hampered the formation of PSII and PSI super- and megacomplexes in the thylakoid membranes as well as their assembly into chiral macrodomains; it also lowered the temperature stability of the PPCs, especially that of LHCII trimers, which led to their monomerization and an anomaly in the photoprotective mechanism of non-photochemical quenching. Role of geranylgeranylated Chls in adverse effects on photosynthetic apparatus of plants acclimated to green light is discussed.

• Keywords
• Arabidopsis thaliana, Chlorophylls, Green light, Structure and function of photosystem II, Thermal stability, Thylakoid membrane,
• MeSH
• Adaptation, Ocular physiology   MeSH
• Arabidopsis metabolism   MeSH
• Chlorophyll metabolism   MeSH
• Photosystem II Protein Complex metabolism   MeSH
• Prenylation MeSH
• Light-Harvesting Protein Complexes metabolism   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Chlorophyll MeSH
• Photosystem II Protein Complex MeSH
• Light-Harvesting Protein Complexes MeSH

Recently, we have found that thermal stability of photosystem II (PSII) photochemistry in spruce needles is higher than in other plants (barley, beech) cultivated under the same temperatures. In this work, temperature dependences of various characteristics of PSII organization were studied in order to obtain complex information on the thermal stability of PSII function and organization in spruce. Temperature dependency of circular dichroism spectra revealed by about 6 °C higher thermal stability of macrodomain organization in spruce thylakoid membranes in comparison with Arabidopsis and barley ones; however, thermal disintegration of light-harvesting complex of PSII did not significantly differ among the species studied. These results thus indicate that thermal stability of PSII macro-organization in spruce thylakoid membranes is enhanced to a similar extent as thermal stability of PSII photochemistry. Clear-native polyacrylamide gel electrophoresis of preheated thylakoids demonstrated that among the separated pigment-protein complexes, only PSII supercomplexes (SCs) revealed considerably higher thermal stability in spruce thylakoids as compared to Arabidopsis and barley ones. Hence we suggest that higher thermal stability of PSII macro-organization of spruce is influenced by the maintenance of PSII SCs in the thylakoid membrane. In addition, we discuss possible effects of different PSII organizations and lipid compositions on the thermal stability of spruce thylakoid membranes.

• Keywords
• Circular dichroism, Norway spruce, Photosystem II organization, Thermal stability, Thylakoid membrane,
• MeSH
• Arabidopsis cytology   physiology   MeSH
• Chlorophyll A MeSH
• Chlorophyll physiology   MeSH
• Circular Dichroism MeSH
• Electrophoresis, Polyacrylamide Gel MeSH
• Fluorescence MeSH
• Photosystem II Protein Complex physiology   MeSH
• Hordeum cytology   physiology   MeSH
• Picea cytology   physiology   MeSH
• Thylakoids physiology   MeSH
• Hot Temperature MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH
• Names of Substances
• Chlorophyll A MeSH
• Chlorophyll MeSH
• Photosystem II Protein Complex MeSH