Energy dissipation in photosynthesis: Does the quenching of chlorophyll fluorescence originate from antenna complexes of photosystem II or from the reaction center?

Abstract

Dissipation of light energy was studied in the moss Rhytidiadelphus squarrosus (Hedw.) Warnst., and in leaves of Spinacia oleracea L. and Arabidopsis thaliana (L.) Heynh., using chlorophyll fluorescence as an indicator reaction. Maximum chlorophyll fluorescence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU)-treated spinach leaves, as produced by saturating light and studied between and -20 degrees C, revealed an activation energy delta E of 0.11 eV. As this suggested recombination fluorescence produced by charge recombination between the oxidized primary donor of photosystem II and reduced pheophytin, a mathematical model explaining fluorescence, and based in part on known characteristics of primary electron-transport reactions, was developed. The model permitted analysis of different modes of fluorescence quenching, two localized in the reaction center of photosystem II and one in the light-harvesting system of the antenna complexes. It predicted differences in the relationship between quenching of variable fluorescence Fv and quenching of basal, so-called F0 fluorescence depending on whether quenching originated from antenna complexes or from reaction centers. Such differences were found experimentally, suggesting antenna quenching as the predominant mechanism of dissipation of light energy in the moss Rhytidiadelphus, whereas reaction-center quenching appeared to be important in spinach and Arabidopsis. Both reaction-center and antenna quenching required activation by thylakoid protonation but only antenna quenching depended on or was strongly enhanced by zeaxanthin. De-protonation permitted relaxation of this quenching with half-times below 1 min. More slowly reversible quenching, tentatively identified as so-called qI or photoinhibitory quenching, required protonation but persisted for prolonged times after de-protonation. It appeared to originate in reaction centers.

Increased Air Temperature during Simulated Autumn Conditions Does Not Increase Photosynthetic Carbon Gain But Affects the Dissipation of Excess Energy in Seedlings of the Evergreen Conifer Jack Pine

“…It has been suggested that high q O in relation to q N is an indicator for high q O (Bukhov et al, 2001;Sane et al, 2003). We found q O /q N Figure 7.…”

A Transient Exchange of the Photosystem II Reaction Center Protein D1:1 with D1:2 during Low Temperature Stress ofSynechococcus sp. PCC 7942 in the Light Lowers the Redox Potential of QB

“…It has been previously hypothesized that the potential for non-photochemical quenching of PSII reaction centers might protect against excess light (10). More recently the reduction of Q A has been suggested as a major requirement for efficient reaction center quenching (43). It has been implied also that the increased population of Q A Ϫ may enhance the dissipation of excess light energy within the PSII reaction center during cold acclimation via its back non-radiative reaction with P680 ϩ , thus complementing the capacity for zeaxanthin cycle-dependent energy quenching (44).…”

Fluorescence as a Tool to Understand Changes in Photosynthetic Electron Flow Regulation

“…Quenching based in the PSII reaction center (as opposed to LHC antenna) has also been observed in higher plants (Bukhov et al 2001;Stroch et al 2004) and green microalgae (Finazzi et al 2004), and possibly in diatoms (Eisenstadt et al 2008). Appearance of reaction centre quenching depends on the balance between light and carbon fixation fluxes (Finazzi et al 2004) along with a clear temperature influence (Kornyeyev et al 2004).…”

“…In contrast to the antennabased quenching, it cannot cause changes in the F o level (Maxwell and Johnson 2000). Nevertheless, as well as the antenna-based quenching it requires thylakoid acidification, but it does not require deepoxidized xanthophylls (Bukhov et al 2001;Finazzi et al 2004). The qI part of this reaction center based quenching is associated with a reversible inactivation of a sub-population of the PSII (Finazzi et al 2004) as well as with PSII photodamage (Kornyeyev et al 2004).…”