Land plants live in a challenging environment dominated by unpredictable changes. A particular problem is fluctuation in sunlight intensity that can cause irreversible damage of components of the photosynthetic apparatus in thylakoid membranes under high light conditions. Although a battery of photoprotective mechanisms minimize damage, photoinhibition of the photosystem II (PSII) complex occur...

In earlier studies we have identified FKBP20-2 and CYP38 as soluble proteins of the chloroplast thylakoid lumen that are required for the formation of photosystem II supercomplexes (PSII SCs). Subsequent work has identified another potential candidate functional in SC formation (PSB27). We have followed up on this possibility and isolated mutants defective in the PSB27 gene. In addition to lack...

Exposure of control (non-hardened) Arabidopsis leaves for 2 h at high irradiance at 5 degrees C resulted in a 55% decrease in photosystem II (PSII) photochemical efficiency as indicated by F(v)/F(m). In contrast, cold-acclimated leaves exposed to the same conditions showed only a 22% decrease in F(v)/F(m). Thermoluminescence was used to assess the possible role(s) of PSII recombination events i...

This review discusses methods for increasing the efficiency of photoelectric conversion systems using photosystem I (PSI) and II (PSII) isolated from thermophilic cyanobacteria. The structure electron transfer pathways PSI PSII are described, followed by a description new type system its application in light-sensing devices or PSII. Photoelectron is demonstrated spectroscopic electrochemical me...

Silicon (Si) is considered a beneficial element for rice (Oryza sativa L.) The objective of this work was to investigate the effects Si in form nanoparticles on growth and physiology under salt stress. Silica (SNPs) were synthesized from husk by sol-gel method. prepared SNPs powders agglomerated semi-spherical nano- sized particles with diameters range 60-135 nm. Three cultivars namely ‘Pokka...

in order to determine the best growing media for gerbera jamesonii under alkaline conditions, a factorial experiment was conducted with two factors, namely: (i) growing medium, and (ii) concentrations of bicarbonate (nahco3) in nutrient solution. results showed that increasing the concentration of nahco3 from 0 to 40 mm in nutrient solution significantly decreased plant growth, maximal quantum ...

Despite our increasingly sophisticated understanding of mechanisms ensuring efficient photosynthesis under laboratory-controlled light conditions, less is known about the regulation of photosynthesis under fluctuating light. This is important because-in nature-photosynthetic organisms experience rapid and extreme changes in sunlight, potentially causing deleterious effects on photosynthetic eff...

Many corals form obligate symbioses with photosynthetic dinoflagellates of the genus Symbiodinium Freudenthal (1962). These symbionts vary genotypically, with their geographical distribution and abundance dependent upon host specificity and tolerance to temperature and light variation. Despite the importance of these mutualistic relationships, the physiology and ecology of Symbiodinium spp. rem...