Nonphotochemical quenching

It has been important to determine if the neoxanthin distortion signature could be detected during the nonphotochemical quenching in vivo. Resonance Raman measurements on leaves and chlo-roplasts of various Arabidopsis mutants have revealed a small increase in the 950 cm 1 region. The relationship between the amplitude of this transition and the amount of NPQ suggests that the LHCII aggregation may be the sole cause of the protective chlorophyll fluorescence quenching in vivo (Ruban et al., 2007). 

Michael Wasielewski of Northwestern University asked Thomas Moore about the type of light fluxes being used to investigate the solar flux. He also asked, Since we all know that photosynthesis has control mechanisms that actually modify electron flow, based on light flux, what kind of prospectus or perspective do we have for control mechanisms in such systems Moore explained that one of the factors that seems to limit natural photosynthesis is the diffusion of carbon dioxide into the system for fixing, so it is important in photosynthesis to throttle back the powerful oxidant when carbon dioxide is limiting. There is a control mechanism called nonphotochemical quenching that is related to the... 

Pogson B, Niyogi KK, Bjbrkman O and Dellapenna D (1998) Altered xanthophyll compositions adversely affect chlorophyll accumulation and nonphotochemical quenching in Arabidopsis mutants. Proc Natl Acad Sci USA 95 13324-13329 Polivka T, Herek JL, Zigmantas D, Akerlund H-E and Sundstrbm V (1999) Direct observation of the (forbidden) Sj state in carotenoids. Proc Natl Acad Sci USA 96 4914-4917 Rabinowitch E (1945) Photosynthesis and Related Processes. Vol. I. Chemistry of Photosynthesis, Chemosynthesis and Related Processes in Vitro and in Vivo. (See scheme 7.V on p. 162.) Interscience Publishers Inc., New York Rabinowitch E (1951) Photosynthesis and Related Topics, Vol. II, Part 1, Spectroscopy and fluorescence Kinetics of Photosynthesis. Interscience Publishers Inc., New York Rabinowitch E (1956)Photosynthesis and Related Processes. Vol. II. Part 2. Kinetics of Photosynthesis (continued) Addenda to Vol. I and Vol. II, Part I. (See p. 1862, paragraph 2.)... 

Fig. /.Diurnal characterization of (top panels) incident PFD and the fraction of the xanthophyl I cycle converted to Z+A, (middle panels) energy dissipation activity quantified as nonphotochemical quenching of F , and the efficiency of open PS II units, and (bottom panels) the fractional allocation of excitation energy absorbed in PS II to photochemistry (P) and thermal energy dissipation (D). The area below the dashed I ines in the bottom two panels represents thermal dissipation associated with the inherent inefficiency of energy transfer within the PS II complex, whereas D above the dashed line represents the regulated thermal dissipation dependent upon Z+A. Plants were characterized in Boulder, Colorado in the summer of 1993 (sunflower) or the summer of, 1995 (Euonymus kiautschovicus). The data for sunflower are redrawn from Demmig-Adams and Adams (1996a) and Demmig-Adams et al. (1997), whereas the data for Euonymus kiautschovicus were redrawn from Verhoeven et al. (1998).

Fig. 2. Diurnal characterization of (top panels) incident PFD, (middle panels) the fraction ofthe xanthophyll cycle converted to Z+A, and (bottom panels) energy dissipation activity quantified as nonphotochemical quenching of F , in leaves of Alocasia brisbanensis on the floor of a subtropical rainforest in Dorrigo National Park in Australia during June of 1994. Data from Logan etal. (1997).

Fig. 7. Fractional carotenoid composition (expressed relative to foliar chlorophyll content top panel) and (bottom graph) time-course of changes in energy dissipation activity quantified as nonphotochemical quenching of F upon the transition from darkness to 2050 /imol photons m s" at 25 C as well as the conversion state of the xanthophyll cycle (fractionally expressed relative to foliar chlorophyll content) determined at the end of each exposure from leaves of Euonymus kiautschovicus collected from plants growing in deep shade or in a fully exposed site in Boulder, Colorado. Data from Demmig-Adams et al. (1995).

Fig. 8. Degree of conversion of the xanthophyll cycle to Z+A (top panel), relative to either total chlorophyll content or total xanthophyll cycle content, as well as (bottom panels) the level of energy dissipation activity quantified from the nonphotochemical quenching of and the efficiency of open PS II units following illumination with a high PFD of between 1800 and 2050 /tmol photons m" s" for 10 to 15 min. Data are means ( SE) of means from 7 species growing in deep shade (solid bars) and 18 species growing in full sunlight (open bars) in Boulder, Colorado. Data from Demmig-Adams (1998),...

Fig. 18. Schematic model of the presumed mechanism for rapidly reversible nonphotochemical quenching (q ) and the proposed mechanism for sustained NPQ (q,). LHCs = light-harvesting complexes of PS II LHCII = major, peripheral light-harvesting complex of PS II LHCII-P = phosphorylated LHCII Z = zeaxanthin...

Ruban AV and Horton P(1995) An investigation ofthe sustained component of nonphotochemical quenching of chlorophyll fluorescence in isolated chloroplasts and leaves of spinach. Plant Physiol 108 721-726... 

Horton P (1996) Nonphotochemical quenching of chlorophyll fluorescence. In Jennings RC, Zucchelli G, Ghetti F and Colombetti G (eds) Light as an Energy Source and Information Carrier in Plant Physiology, pp 99-111. Plenum Press, New York... 

III. Unanswered Questions Concerning the Roles of the Xanthophyll Cycle in nonphotochemical Quenching... 

Fig. 5.30 General behaviour of the chlorophyll a fluorescence after exposing a dark-adapted leaf to light. The fluorescence intensity first increases due to a decrease of photochemical quenching (a) and then decreases due to an increase of nonphotochemical quenching (b)...

The slow decrease of the fluorescence intensity at later times is termed non-photochemical quenching". Nonphotochemical quenching seems to be essential in protecting the plant from photodamage, or may even be a result of moderate photodamage. The processes that lead to nonphotochemical quenching are often referred to as photoinhibition". 

This difficulty is easily avoided by fluorescence lifetime detection. By using the sequential recording capability of multidimensional TCSPC, the fluorescence transients can be directly observed. A simple setup for recording the nonphotochemical quenching is shown in Fig. 5.31. 

Fig. 5.31 Recording the nonphotochemical quenching transient of chlorophyll a. The TCSPC module records a single sequence of fluorescence decay curves starting with the switch-on of the laser...

Govindjee, M.J. Seufferheld, Nonphotochemical quenching of chlorophyll a Fluorescence Early history and characterization of two xanthophyll-cycle mutants of Chlamydomonas Reinhardtii, Funct. Plant Biol. 29, 1141-1155 (2002)... 

Standfuss J, Terwisscha van Scheltinga AC, Lamborghini M, Kuhlbrandt W (2005) Mechanisms of photoprotection and nonphotochemical quenching in pea light-harvesting complex at 2.5 A resolution. EMBO J 24(5) 919-928... 

Weis and Berry (1) have demonstrated an inverse, linear relationship between the quantxim yield of photochemistry for open (i.e. Qa is unreduced) PSII centers versus nonphotochemical quenching as expressed by the coefficient qjjp (Fig. 1). The results reported here extend studies of the relationship between qjgp and photochemical quantum yield of PSII to leaf tissue subjected to an increase in transpiration due to an elevated vapor pressure deficit (VPD). 

Another component of nonphotochemical quenching recovers very slowly. This component is usually called photoinhibition. This photoinhibition can require hours to days for reversal. It is considered a stress response. 

Wilson KE, Krol M, and Huner NPA. Temperature-induced greening of Chlorella vulgaris. The role of the cellular energy balance and zeaxanthin-dependent nonphotochemical quenching. Planta 2003 217 616-627. 

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