ISSN 1021-4437, Russian Journal of Plant Physiology, 2009, Vol. 56, No. 1, pp. 6–13. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © A.A. Kosobrykhov, 2009, published in Fiziologiya Rastenii, 2009, Vol. 56, No. 1, pp. 8–16.
Plants growing under both natural and artiﬁcial con-
ditions constantly experience the effects of changing
environmental factors, such as levels of lighting, tem-
perature, and CO
concentration. Plants adapt dynami-
cally to these changes; the rhythm of this adaptation is
determined by the pattern of environment changing.
Many scientists, both in the past (Linnaeus, Darwin,
Pfeffer, see ) and recently [2–4], have noted the
rhythmic nature of the changes in the rates of physio-
logical processes in plants. Plant responses to changing
light intensity were studied most thoroughly [5, 6].
The dynamic aspect of physiological processes in
plants attracts more and more attention, although the
research approaches and methods are changing. Cur-
rently, most attention is focused on studying the
responses of the photosynthetic apparatus to short-term
(seconds or minutes) changes in light intensity. In these
experiments, the ﬂuctuation of plant leaf irradiance due
to wind, clouds, etc. are modeled [7–9].
The study of the inﬂuence of more prolonged
(hours) daily temperature ﬂuctuations on plant growth
and productivity [10–12], photosynthesis, respiration,
and some metabolic processes [13–15] revealed the
main patterns of plant thermoperiodism.
In a number of cases, rhythmic inﬂuences with a
certain period can trigger transient processes leading to
an increase in the photosynthetic rate and plant produc-
tivity [16, 17]. At the same time, we have not encoun-
tered works where the inﬂuence of a periodical increase
in the ambient CO
] on the photosyn-
thesis rate, plant growth, and productivity was studied.
Thus, we believe that the temporal variability of the
photosynthetic apparatus responses to the elevation of
]and the mechanism of the inﬂuence of [C
ical elevation on plants needs to be studied. It is impor-
tant for the evaluation of adaptive changes in plant pho-
tosynthesis, as well as for ﬁnding new opportunities to
regulate plant productivity under artiﬁcial growth con-
The objective of this work was to study the adaptive
changes in the photosynthetic apparatus under the
inﬂuence of periodical [C
] elevation and the mecha-
nisms that allow plants to adapt to a changing [C
included studying the inﬂuence of periodical, with a
period of a few hours, ambient CO
changes on the photosynthetic apparatus and carbohy-
drate content in cucumber plants.
MATERIALS AND METHODS
Plant material and growth conditions.
L., hybrid Moskovsky tepli-
chniy) were grown on Knop nutrient medium in KV-1R
growth chambers at a normal or elevated CO
Activity of the Photosynthetic Apparatus at Periodic
Elevation of CO
A. A. Kosobryukhov
Institute of Basic Problems of Biology, Russian Academy of Sciences, Pushchino, Moscow oblast, 142290 Russia;
Received January 22, 2008
— We studied the inﬂuence of prolonged (a few weeks) and short-term (a few hours) periodical ele-
vation of the ambient CO
]) on the photosynthetic apparatus and carbohydrate content in the
third leaf of three-week-old cucumber (
L.) plants. On the basis of experimental data and sub-
sequent modeling, we revealed the limiting processes in the photosynthetic apparatus functioning: Rubisco
activity, the rate of ribulose bisphosphate (CO
acceptor) regeneration, the rate of triose phosphate utilization
in the Calvin cycle, and the inﬂuence of stomata on the photosynthesis rate. An increase in soluble carbohydrate
content and a decrease in starch accumulation at a short-term [C
] elevation indicate an important role of car-
bohydrate accumulation and their partition between organs in the regulation of the photosynthesis. We con-
cluded that periodic [C
] elevation can be used to improve plant productivity.
Key words: Cucumis sativus - photosynthesis - Rubisco – CO
concentration – carbohydrates
concentration; RuBP—ribulose bisphosphate.