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1. Analysis of photosynthetic responses and adaptation to nitrogen starvation in Chlorella using in vivo chlorophyll fluorescence

Creator:
Sayed, O. H.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
carotenoids, oxygen evolution, photosystem 2, species differences, and respiration
Language:
Multiple languages
Description:
Nitrogen (N) starvation resulted in degreening, inhibition of photosynthetic oxygen evolution and dark respiration, reduced survival, and increased age-specific mortality in both Chlorella fusca and Chlorella vulgaris. Analysis of in vivo chlorophyll (Chl) fluorescence induction kinetics revealed the presence of N-starvation-induced changes at the level of degreened thylakoids in both species. These changes included decreased yield of the photochemistry of photosystem 2 (PS2), and a declined photosynthetic efficiency. Synthesis of secondary carotenoids represented a biochemical change in carotenogenesis that had a photoprotective effect in degreened C. fusca. This inferred photoprotection was reflected in the delayed inhibition of oxygen evolution and improved survival of C. fusca under N-starvation. The effect was further elucidated by comparison with C. vulgaris which was not able to synthesize secondary carotenoids under the same conditions.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Effects of long-term action of high temperature and high light on the activity and energy interaction of both photosystems in tomato plants

Creator:
Faik, A., Popova, A. V., and Velitchkova, M.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
karotenoidy, chlorofyl, vysoké teploty, carotenoids, chlorophyll, high temperatures, anténní komplexy, rychlost přenosu elektronů, fluorescence, pigment-proteinové komplexy, rajče, fotosystém, antenna complexes, electron transport rate, pigment-protein complexes, spillover, tomato, photosystem, 2, and 581
Language:
Multiple languages
Description:
The acclimation to high light, elevated temperature, and combination of both factors was evaluated in tomato (Solanum lycopersicum cv. M82) by determination of photochemical activities of PSI and PSII and by analyzing 77 K fluorescence of isolated thylakoid membranes. Developed plants were exposed for six days to different combinations of temperature and light intensity followed by five days of a recovery period. Photochemical activities of both photosystems showed different sensitivity towards the heat treatment in dependence on light intensity. Elevated temperature exhibited more negative impact on PSII activity, while PSI was slightly stimulated. Analysis of 77 K fluorescence emission and excitation spectra showed alterations in the energy distribution between both photosystems indicating alterations in light-harvesting complexes. Light intensity affected the antenna complexes of both photosystems stronger than temperature. Our results demonstrated that simultaneous action of high-light intensity and high temperature promoted the acclimation of tomato plants regarding the activity of both photosystems in thylakoid membranes., A. Faik, A. V. Popova, M. Velitchkova., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public