Dynamic feedback of the photosystem II reaction centre on photoprotection in plants

Abstract

Photosystem II of higher plants is protected against light damage by thermal dissipation of excess excitation energy, a process that can be monitored through non-photochemical quenching of chlorophyll fluorescence. When the light intensity is lowered, non-photochemical quenching largely disappears on a time scale ranging from tens of seconds to many minutes. With the use of picosecond fluorescence spectroscopy, we demonstrate that one of the underlying mechanisms is only functional when the reaction centre of photosystem II is closed, that is when electron transfer is blocked and the risk of photodamage is high. This is accompanied by the appearance of a long-wavelength fluorescence band. As soon as the reaction centre reopens, this quenching, together with the long-wavelength fluorescence, disappears instantaneously. This allows plants to maintain a high level of photosynthetic efficiency even in dangerous high-light conditions.

Disentangling Changes in the Spectral Shape of Chlorophyll Fluorescence: Implications for Remote Sensing of Photosynthesis

“…The spectral shape associated with changes in NPQ shows a similar pattern to Farooq et al (2018) and Lambrev et al (2010), suggesting that the change at F t,720 is the result of rapidly reversible energy-dependent quenching, whereas the decrease at F t,680 is induced by both PsbS-independent mechanisms and energydependent quenching. Further, the decrease in F t,680 under increasing light has been noted in other works and attributed to changes in PSII compared to PSI fluorescence (Nematov et al, 2017), since PSI fluorescence is thought to be negligible <680 nm and not modified by changes in NPQ/PQ (Franck et al, 2002;Palombi et al, 2011;Figures S7 and S8).…”

“…The magnitude and spectral shape of leaf ChlF are known to change with irradiance conditions (Pinto et al, ), chlorophyll concentration (Buschmann, ; Gitelson et al, ; Hak et al, ; Lichtenthaler et al, ), physiological condition (PSI/PSII contributions, NPQ; Franck et al, , ; Lambrev et al, ; Palombi et al, ; Rizzo et al, ), temperature (Agati, ; Croce et al, ), photosystem stoichiometry and structure (Farooq et al, ; Johnson et al, ), and leaf optical properties (Gitelson et al, ; Vilfan et al, ). At steady state, a large body of research suggests that deviations in the red (~685 nm) to far‐red (~750 nm) ChlF ratio are controlled by Chl concentration, which regulates the degree of reabsorption in the red part of the spectrum along the escape path of the photon (Buschmann, ; Gitelson et al, ; Lichtenthaler et al, ).…”

Fluorescence Microscopy of Single Liposomes with Incorporated Pigment–Proteins

“…Due to the presence of two types of photosystems within the membrane as well as two types of excitation quenchers (RCs and NPQ-traps), the spectroscopic signatures of various parallel processes occurring in the thylakoid membrane are not easily resolved [5][6][7][8][9] , which severely complicates the detailed direct investigation of the molecular mechanisms involved. Instead, different photosynthetic units or just pigment-protein complexes are usually extracted from the thylakoid membrane and then are studied separately either in the detergent-solubilized form utilizing conventional bulk spectroscopy methods [10][11][12][13][14][15][16][17] or being immobilized on some surface while applying the single-molecule microscopy techniques [18][19][20][21][22] .…”

Decoding the gene coexpression network underlying the ability of Gevuina avellana to live in diverse light conditions

“…Based on the different configurations and redox state of the pigment-protein system of the LHCs, under low light (LL) conditions a large lightharvesting antenna system ensures high efficiency of light capture, whereas under HL, plants dissipate excess absorbed light energy as heat via the nonphotochemical quenching mechanism (NPQ). It is known that protonation of the PsbS protein in the LHC II and the reversible conversion of the xanthophyll violaxanthin into zeaxanthin are key processes in the activation of the NPQ mechanism (Farooq et al, 2018). Nevertheless, there is still little information about the genetic aspects regulating the photochemical and photoprotective responses of plants to fluctuating light.…”