The first step of photosynthesis in plants is the absorption of sunlight by pigments in the antenna complexes of photosystem II (PSII), followed by transfer of the nascent excitation energy to the reaction centers, where long-term storage as chemical energy is initiated. Quantum mechanical mechanisms must be invoked to explain the transport of excitation within individual antenna. However, it i...

introduction salinity has various effects on plant growth by affecting physiological processes. the decline in plant productivity under saline condition, frequently linked with the reduction of photosynthetic capability. it has been reported that efficiency of psii photochemistry (fv/fm) of numerous plant species have been decreased due to salt stress studies have shown that salicylic acid (sa...

Chlamydomonas reinhardtii double mutant npq2 lor1 lacks the β,ε-carotenoids lutein and loroxanthin as well as all β,β-epoxycarotenoids derived from zeaxanthin (e.g. violaxanthin and neoxanthin). Thus, the only carotenoids present in the thylakoid membranes of the npq2 lor1 cells are β-carotene and zeaxanthin. The effect of these mutations on the photochemical apparatus assembly and function was...

Different representative of algae and cyanobacteria were isolated from a freshwater habitat and cultivated in laboratory to compare their photoacclimation capacity when exposed to a wide range of light intensity and to understand if this factor may modify natural community dominance. All species successfully acclimated to all light intensities and the response of phytoplankton to increased ligh...

Photosystem II (PSII) is the unique pigment–protein complex that capable of evolving molecular oxygen using solar energy. The activity PSII determines overall productivity all oxygenic photosynthetic organisms. It well known absence HCO3− induces a drop in PSII. However, it not yet clear what type photochemical reaction, single turn-over or multiple turn-over, involved in. Kinetic parameters th...

The effects of exposure to increasing manganese concentrations (50-1500 µM) from the start of the experiment on the functional performance of photosystem II (PSII) and photosystem I (PSI) and photosynthetic apparatus composition of Arabidopsis thaliana were compared. In agreement with earlier studies, excess Mn caused minimal changes in the PSII photochemical efficiency measured as F(v)/F(m), a...

In this study, the function of the NAD(P)H dehydrogenase (NDH)-dependent pathway in suppressing the accumulation of reactive oxygen species in chloroplasts was investigated. Hydrogen peroxide accumulated in the leaves of tobacco (Nicotiana tabacum) defective in ndhC-ndhK-ndhJ (DeltandhCKJ) at 42 degrees C and 4 degrees C, and in that of wild-type leaves at 4 degrees C. The maximum quantum effic...

many phragmites-dominated wetlands have been markedly salinized and alkalinized in the songnen plain, northeastern china. agricultural wastewater with high nitrogen content has been discharged into these alkalinized-salinized wetlands. to understand the effect of salinity-alkalinity on reed (phragmites australis) seedlings at various nitrogen levels, we examined photosynthesis rate, chlorophyll...

Although sunlight provides the energy necessary for plants to survive and grow, light can also damage reaction centers of photosystem II (PSII) and reduce photochemical efficiency. To prevent damage, plants possess photoprotective mechanisms that dissipate excess excitation. A subset of these mechanisms is collectively referred to as NPQ, or nonphotochemical quenching of chlorophyll a fluoresce...