Effects of light environment on the induction of chlorophyll fluorescence in leaves: a comparative study of Tradescantia species of different ecotypes.

In this work, using a PAM-fluorimetry technique, we have compared effects of plant adaptation to the light or dark conditions on the kinetics of chlorophyll a fluorescence yield in Tradecantia leaves of several species (Tradescantia albiflora, Tradescantia fluminensis, Tradescantia navicularis, and Tradescantia sillamontana), which represent plants of different ecotypes. Two fluorescence parameters were used to assess photosynthetic performance in vivo: non-photochemical quenching (NPQ) of chlorophyll fluorescence (q(NPQ)) determined by energy losses in the light-harvesting antenna of photosystem 2 (PS2), and PS2 operating efficiency (Φ(PSII)). Comparative study of light-induced changes in q(NPQ) and Φ(PSII) has demonstrated that shade-tolerant Tradecantia species (T.

Regulation of electron transport in C(3) plant chloroplasts in situ and in silico: short-term effects of atmospheric CO(2) and O(2).

In this work, we have investigated the effects of atmospheric CO(2) and O(2) on induction events in Hibiscus rosa-sinensis leaves. These effects manifest themselves as multiphase kinetics of P(700) redox transitions and non-monotonous changes in chlorophyll fluorescence. Depletion of CO(2) and O(2) in air causes a decrease in linear electron flux (LEF) and dramatic lowering of P(700)(+) level.

Functional and topological aspects of pH-dependent regulation of electron and proton transport in chloroplasts in silico.

In this work, we summarize results of computer simulation of electron and proton transport processes coupled to ATP synthesis in chloroplasts performed within the frames of a mathematical model developed as a system of differential equations for concentrations of electron carriers and hydrogen ion inside and outside the granal and stromal thylakoids. The model takes into account topological peculiarities and lateral heterogeneity of the chloroplast lamellar system. This allowed us to analyze the influence of restricted diffusion of protons inside small compartments of a chloroplast (e.

[pH-dependent regulation of electron transport in chloroplasts. Computer simulation investigation].

A mathematical model for the description of the key stages of photosynthetic electron transport and transmembrane proton transfer in chloroplasts is presented. Numerical modeling of electron and proton transport with due regard for regulatory processes on the donor and acceptor sites of photosystem I (PS I) was performed. The influence of pH-dependent activation of the Calvin cycle enzymes and energy dissipation in PS II (nonphotochemical quenching of chlorophyll fluorescence) on the kinetics of light-reduced redox transients of P700, plastoquinone and NADPH, as well as intrathylakoid pH(in), and ATP was studied.

Oxygen as an alternative electron acceptor in the photosynthetic electron transport chain of C3 plants.

This study deals with effects of oxygen on the kinetics of P(700) photoinduced redox transitions and on induction transients of chlorophyll fluorescence in leaves of C(3) plants Hibiscus rosa-sinensis and Vicia faba. It is shown that the removal of oxygen from the leaf environment has a conspicuous effect on photosynthetic electron transport. Under anaerobic conditions, the concentration of oxidized P700 centers in continuous white light was substantially lower than under aerobic conditions.