ACTA BIOLOGICA CRACOVIENSIA

PHOTOSYNTHESIS, PHOTOCHEMISTRY, AND PHOTOPROTECTION BY CAROTENOIDS
Chromatography and resonance Raman spectroscopy data will be
presented and discussed. The understanding of such phenomenon
may help in the elucidation of color variation and changes
due to carotenoid-protein interactions in other living organisms.
2.14.
The role of carotenoid isomerase
in photoprotection in rice
Hualing Mi
National Laboratory of Plant Molecular Genetics, Institute of Plant
Physiology and Ecology, Shanghai Institutes for Biological
Sciences, Chinese Academy of Sciences, 300 Fenglin Road,
Shanghai, 200032, China, mihl@sippe.ac.cn
In this work, we isolated a yellowish-leaf mutant from Oryza sativa
(rice). Map-based cloning approach revealed that the gene
encodes a predicted carotenoid isomerase named as OsCRTISO.
Comparison of wild type, the zeaxanthin (Z) was hardly
detectable and lutein was only 30%, while violaxanthin (V) and
antheraxanthin (A) were increased nearly 3-fold and neoxanthin
and -carotene increased evidently. In addition, the xanthophylls
cycle (A+Z)/(A+Z+V) decreased by about 45% under growth light
condition (400 μmol photons m -2 s -1 ) and 53% under high light
(1000 μmol photons m -2 s -1 ) in the mutant. These results indicate
that both the de-epoxidation of antheraxanthin to zeaxanthin and
conversion of lycopen to lutein were suppressed in the mutant.
Further analysis indicates that the mutation caused decrease in
(1) LHCII trimers and supercomplex of photosystem II (PS II), (2)
the capacity of PS II; (3) other thermal dissipation pathways, such
as nonphotochemical quenching and state transitions; (4) accumulation
of hydrogen peroxide in the leaves. The suppression of
PS II capacity was much more significantly under the high light
condition. Further investigation indicates that the amount of the
core protein CP43 and CP47 especially in the supercomplexes of
PS II and their expression in the transcript or translation level
was suppressed in the mutant. Based on those results, we suggested
that the low level of lutein and suppression of xanthophyll
cycle increase the sensitivity of rice plant to light. The possible
role of caroteinoid isomerase in photoprotection of PS II is discussed.
2.15.
DFT studies of open chain carotenoid radicals:
dependence on conjugation length
Ligia Focsan1 , Michael Bowman1 , Lowell Kispert1 ,
Péter Molnár2 , József Deli3 1Department of Chemistry, The University of Alabama, 250
Hackberry Lane, Tuscaloosa, AL 35487-0336, US,
focsa001@crimson.ua.edu, mkbowman@as.ua.edu,
lkispert@bama.ua.edu
2Department of Pharmacognosy, University of Pécs, Medical
School, Hungary, H-7624 Pécs, Rókus str. 2, Hungary,
Peter.Molnar@aok.pte.hu
3Department of Biochemistry and Medical Chemistry, University of
Pécs, Medical School, Hungary, H-7624 Pécs, Szigeti str. 12,
Hungary, Jozsef.Deli@aok.pte.hu
Previous EPR (electron paramagnetic resonance) and DFT
(density functional theory) studies on carotenoids containing
terminal rings like zeaxanthin and violaxanthin (Focsan et al.,
2008), lutein (Lawrence et al., 2008), 9'-cis neoxanthin (Focsan
et al., 2009) and astaxanthin (Polyakov et al., 2010) have
Vol. 53, suppl. 1, 2011
shown that carotenoid radical cations deprotonate to form neutral
radicals. Proton loss occurs preferentially from the methylene
and methyl groups of the terminal rings, while the presence
of functional groups like epoxy, carbonyl and allene on the
terminal rings prevents this loss. As a consequence of deprotonation,
a change in the unpaired electron spin distribution produces
larger hyperfine coupling constants for the neutral radicals
than for the radical cations and thus permits their identification
in a mixture analyzed by using Mims ENDOR techniques.
Here we describe open chain carotenoids, either symmetric
or asymmetric, with varying conjugation length (n=9-15 carbon
atoms) and different functional groups. The addition of protons
and functional groups like methoxy or carbonyl to a fully conjugated
open chain carotenoid causes a preferential proton loss
from the radical cation formed. Formation of carotenoid radicals
of dehydrolycopene, lycopene, neurosporene, spheroidene,
spheroidenone, anhydrorhodovibrin and spirilloxanthin has
been investigated using DFT calculations which revealed the
most favorable neutral radicals, their unpaired spin density distribution,
the relative energies and the hyperfine coupling constants.
This study was supported by U.S. Dept. of Energy Grant No. DE-FG02-
86ER 13465 and Grants OTKA K 76176 and K 83898 (Hungarian
Scientific Research Foundation).
REFERENCES
FOCSAN AL, BOWMAN MK, KONOVALOVA TA, MOLNÁR P, DELI J, DIXON DA,
KISPERT LD. 2008. Pulsed EPR and DFT characterization of radicals
produced by photo-oxidation of zeaxanthin and violaxanthin
on silica-alumina. The Journal of Physical Chemistry B 112:
1806-1819.
LAWRENCE J, FOCSAN AL, KONOVALOVA TA, MOLNÁR P, DELI J, BOWMAN MK,
KISPERT LD. 2008. Pulsed ENDOR studies of carotenoid oxidation
in Cu(II)-substituted MCM-41 molecular sieves. The Journal
of Physical Chemistry B 112: 5449-5457.
FOCSAN AL, MOLNÁR P, DELI J, KISPERT LD. 2009. The structure and
properties of 9'-cis neoxanthin carotenoid radicals by EPR measurements
and DFT calculations. The Journal of Physical
Chemistry B 113: 6087-6096.
POLYAKOV NE, FOCSAN AL, BOWMAN MK, KISPERT LD. 2010. Free radical
formation in novel carotenoid metal ion complexes of astaxanthin.
The Journal of Physical Chemistry B 114: 16968-16977.
2.16.
17–22 July 2011, Krakow, Poland
Carotenoids content in etiolated seedlings of
three A. thaliana ecotypes
Beata Myśliwa-Kurdziel, Małgorzata Jemioła-Rzemińska,
Przemysław Malec, Kazimierz Strzałka
Department of Plant Physiology and Biochemistry, Faculty of
Biochemistry, Biophysics and Biotechnology, Jagiellonian
University, Gronostajowa 7, 30-387 Kraków, Poland,
b.mysliwa-kurdziel@uj.edu.pl, malgorzata.jemiola@gmail.com,
malecpk@gmail.com, kazimierzstrzalka@gmail.com
Angiosperms require light for their morphogenesis. While
growing in the dark, seedlings become etiolated, which means,
among others, that they are yellowish, contain no chlorophyll,
and develop etioplasts instead of chloroplasts. Biosynthesis of
chlorophyll is stopped at the level of protochlorophyllide
(Pchlide) formation, that accumulates in etioplasts. The lighttriggered
reduction of Pchlide to chlorophyllide, catalysed by a
light-dependent protochlorophyllide oxidoreductase (EC
1.3.1.33), induces the deetiolation process. Furthermore, light
regulates also biosynthesis of carotenoids, indirectly via phytochrome-controlled
level of phytoene synthase, the first
enzyme of the pathway. Etiolated seedlings accumulate
41