ISSN 1021-4437, Russian Journal of Plant Physiology, 2009, Vol. 56, No. 5, pp. 607–615. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © T.G. Maslova, N.S. Mamushina, O.A. Sherstneva, L.S. Bubolo, E.K. Zubkova, 2009, published in Fiziologiya Rastenii, 2009, Vol. 56, No. 5, pp. 672–681.
The problem of winter hardiness of evergreen coni-
fer plants growing at high and middle latitudes is
actively discussed in literature [1, 2]. The researchers
emphasize the following paradoxical phenomenon
observed in plants of this ecological group. The assim-
ilating organs of these plants do not absorb
ambient temperature is low, because, under these con-
ditions, the Calvin cycle enzyme activity is suppressed.
At the same time, the primary reactions of light quanta
absorption occurring in the chloroplast pigment appara-
tus are less sensitive to low temperatures, i.e., in theory
they can function under these conditions . In winter
no signiﬁcant chlorophyll degradation or needle and
scaly assimilating organ bleaching is observed in gym-
nosperm plants . This allows assuming that the pho-
tosynthetic apparatus in evergreen conifers possesses
complex protective mechanisms that help to avoid pho-
toinhibition under conditions of low above-zero and
below-zero temperatures. An important component of
this complex protection system is carotenoids, which
perform a number of functions in chloroplasts: (1) sta-
bilize chloroplast membranes and proteins of antenna
complexes [3, 4]; (2) absorb and scatter excitation
energy, serving as photoprotectants of the photosyn-
thetic apparatus [2, 4]; (3) are potential scavengers of
dangerous triplet chlorophyll and singlet oxygen [5, 6].
Apart from that, an important role in this protection
system belongs to the violaxanthin cycle (VC), which
was discovered in the green leaf by Sapozhnikov et. al.
. Later, the protective role of the VC was described
in detail for angiosperms  and gymnosperms [9, 10].
The violaxanthin cycle includes two reactions. The for-
ward reaction is the light-dependent conversion of vio-
laxanthin into zeaxanthin (via an intermediate caro-
tenoid antheraxanthin); in this reaction oxygen is
removed by the enzyme deepoxidase. The reverse reac-
tion is the light-independent conversion of zeaxanthin
into violaxanthin with the participation of molecular
oxygen and the enzyme epoxidase .
Some plants, particularly evergreens, are capable of
further zeaxanthin oxidation into secondary red caro-
tenoids, e.g. rhodoxanthin, during acclimation to cold
Seasonal Structural and Functional Changes
in the Photosynthetic Apparatus of Evergreen Conifers
T. G. Maslova, N. S. Mamushina, O. A. Sherstneva, L. S. Bubolo, and E. K. Zubkova
Komarov Botanical Institute, Russian Academy of Sciences, ul. Professora Popova 2, St. Petersburg, 197376 Russia;
Received March 6, 2008
—We conducted a detail study of the photosynthetic apparatus in assimilating organs of three intro-
duced evergreen conifer species:
S. et Z. ex E. (Far-Eastern yew),
vitae “green”), and
f. “Reingold” (arbovitae “yellow”) at various times in their life cycle. We
studied the potential photosynthesis rate; composition and ratios of pigments, including primary carotenoids;
the violaxanthin cycle (VC) activity, the synthesis of a secondary carotenoid, rhodoxanthin; and chloroplast
ultrastructure. In winter and spring,
-carotene and lutein (primary carotenoids) contents were relatively con-
stant in yew and arbovitae “yellow”. In December, the VC in yew was balanced and in arbovitae “yellow”
unbalanced. In arbovitae “yellow”, the zeaxanthin pool was heterogeneous, and only part of it took part in the
VC. It can be assumed that the other part of the pool can be oxidized to form a secondary carotenoid, rhodox-
anthin. This secondary carotenoid was also accumulated in arbovitae “green”; its synthesis took place during
the season, when the photosynthesis rate of plants was the lowest, and a signiﬁcant chloroplast reorganization
occurred (the number of thylakoids in grana decreased and plastoglobules appeared). We suppose that rhodox-
anthin forms a ﬁlter for the light under the conditions of high insolation in winter. Thus, the evergreen conifer
plants studied, which are adapted to growing at high latitudes where temperature is low and insolation is high
in winter and spring, have a system for protecting the photosynthetic apparatus against photodestruction. In the
basis of this system, the primary and secondary carotenoids lie, whose content changes during the year.
Key words: Taxus cuspidate - Arbovitae occidentalis - Arbovitae occidentalis f. “Reingold” - carotenoids -
lutein - rhodoxanthin - violaxanthin - zeaxanthin - photosynthesis - chlorophyll - chloroplast ultrastructure
: LHC—light-harvesting complex; PPR—potential
photosynthesis rate, PS—photosystem; VC—violaxanthin cycle.