Xanthophyll mutants

Absorption and Raman analysis of LHCII complexes from xanthophyll biosynthesis mutants and plants containing unusual carotenoids (e.g., lactucoxanthin and lutein-epoxide) should also be interesting, since the role of these pigments and their binding properties are unknown. Understanding the specificity of binding can help to understand the reasons for xanthophyll variety in photosynthetic antennae and aid in the discovery of yet unknown functions for these molecules. 

Recent studies, using an Arabidopsis mutant defective in the xanthophyll cycle, point to a chlorophyllbinding protein PsbS, which participates in nonphoto-... 

The occurrence of xanthophyll dioxygenase, which releases xanthoxin from xanthophyll, was found using the ABA-deficient mutant vpl4oi Z. mays.650 Xanthophyll dioxygenase cleaves the double bond between C-ll (C-11 ) and C-12 (C-12 ) of 9-Z-violaxanthin (43) and 9 -Z-neoxanthin to give xanthoxin (5).651 The mRNA of xanthoxin dioxygenase in the leaves of P. vulgaris increased upon water stress and decreased upon... 

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. 

Pathways. Studies of carotenoid transformations that take place when a mutant strain, PGl, of the green alga Scenedesmus obliquus is transferred from dark to light conditions have indicated that the transformations 15-cw-phytoene (180) 15-c/5-phytofluene (181) - 15-cis- -carotene (182) -> trans-C-caro-tene (183) (Scheme 7) take place in the biosynthesis of the normal cyclic carotenoids. The results were also in agreement with the formation of the xanthophylls lutein (16) and zeaxanthin (174) from the corresponding carotenes. 

Niyogi KK, Grossman and Bjbrkman O (1998) Arabidopsis mutants define a central role for the xanthophyll cycle in the regulation of photosynthetic energy conversion. Plant Cell 10 1121-1134... 

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.)... 

A. The Xanthophyll Biosynthetic Mutants of Arabidopsis thaliana-. An Overview.27... 

Prior to 1995, only one locus affecting Xanthophyll biosynthesis in photosynthetic tissues of Arabidopsis had been identified, the ABA i locus, the mutation of which disrupts zeaxanthin deepoxidase, one of two xanthophyll cycle enzymes (Koomneef et al, 1982 Rock and Zeevaart, 1991 Rock et al., 1992). As a step toward advancing understanding of xanthophyll biosynthesis, incorporation, and function in plants, the author s laboratory has screened for and identified mutations defining two additional loci required for xanthophyll biosynthesis in Arabidopsis, LUTl and LUT2 LUT= LUTein deficient). Mutations at either locus result in defects in the synthesis of lutein, the most predominant xanthophyll in plants. Singly and in combination with the aba mutation, these lut mutations have allowed the genetic construction of five distinct mutant lines which differ dramatically in their carotenoid composition relative to wild-type Arabidopsis. In the remainder of this chapter I will first briefly discuss the aba mutation followed by a... 

The loss of lutein (80 to 100 %) in lutl and lut2 is compensated for by increases in the abundance of other carotenoids, most notably specific P, 13-carotenoids (Fig. 4). lutl mutants accumulate the biosynthetic intermediate, zeinoxanthin to approximately 50% of the wild-type lutein level and in addition have elevated levels of the xanthophyll cycle carotenoids violaxanthin, antheraxanthin and zeaxanthin. Iut2 mutants have an even larger increase in xanthophyll cycle pigments, plus a smaller increase in /3-carotene. Antheraxanthin and zeaxanthin normally accumulate transiently in response to high... 

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