Xanthophylls quenching

Gilmore, A. and H. Yamamoto (1993). Linear models relating xanthophylls and lumen acidity to non-photochemical fluorescence quenching, evidence that antheraxanthin explains zeaxanthin-independent quenching. Photosynth Res 35 67-68. 

The evidence available to date indicates that lutein and zeaxanthin could contribute to achieving the last two objectives, namely, the reduction of actinic insults caused by blue light and quenching reactive oxygen species. This follows from the dual presence of xanthophylls in the macula their prereceptoral location and their presence within the outer segments themselves, as discussed in Section 13.5. 

Niyogi KK, Bjorkman O and Grossman AR. (1997). Chlamydomonas xanthophyll cycle mutants identified by video imaging of chlorophyll fluorescence quenching. Plant Cell 9,1369-1380. 

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.)... 

Chlamydomonas mutants have been isolated that are deficient either in violaxanthin de-epoxidase or zeaxanthin epoxidase. Using these mutants, it could be demonstrated that only part of the non-photochemical quenching observed in Chlamydomonas is dependent on the formation of zeaxanthin (Niyogi etal., 1997a). It will be interesting to see whether the absence of xanthophyll epoxidase or de-epoxidase products has an effect on the assembly of light-harvesting complexes in these mutants. 

An atomic resolution model of the plant lightharvesting complex LHC-II has been published (Kiihlbrandt, 1994 Ktihlbrandt et al., 1994 Hunter et al., 1994b). Two xanthophyll molecules are located at the eenter of the complex and were identified as lutein based on the fact that this pigment is the most abundant. They apparently have a structural role in addition to their triplet quenching ability (Plumley and Schmidt, 1987 Paulsen et al., 1990 Heinze et al., 1997). The main xanthophylls are lutein, neoxanthin, and violaxanthin (Siefermann-Harms, 1985, 1990a). Time-resolved optical spectroscopy showed that at least two spectroscopically distinct xanthophylls participate in triplet quenching, apparently lutein and violaxanthin (Peterman et al., 1995, 1997). 

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).

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