ISSN 10214437, Russian Journal of Plant Physiology, 2013, Vol. 60, No. 3, pp. 383–387. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © M.I. Sysoeva, E.F. Markovskaya, E.G. Sherudilo, 2013, published in Fiziologiya Rastenii, 2013, Vol. 60, No. 3, pp. 393–398.
As sessile organisms, plants have evolved special
ized signaling systems ensuring adequate plant
responses to variable environmental conditions. In
particular, such factors as light and temperature are
known to control metabolism and perform warning
and signaling functions .
Plants perceive light stimuli by means of special
ized photoreceptors, including phytochromes. The
thermal sensitivity of phytochromes  makes them a
likely candidate for the role of temperature sensor in
plants [3–5]. Even slight variations in temperature
might affect the phytochromemediated signaling
through rearrangement of relations between various
One of the most widespread phytochromes in light
grown plants is phytochrome B  that participates in
thermoperiodic plant responses , formation of cold
hardiness , expression of pathogenesisrelated
genes and hypersensitive response to infection ,
regulation of drought tolerance  and water rela
tions . We showed previously that phytochrome B
is implicated in the development of cold hardiness in
cucumber plants under shortterm periodic cooling,
although it is uninvolved in responses to prolonged
lowtemperature treatments under short and long
day conditions . The shortterm chilling of
cucumber plants during the night period was found to
induce significantly larger increments in cold toler
ance than the permanent lowtemperature treatment
applied throughout the diurnal cycle; similar trends
were observed in various plant species [13, 14]. The
involvement of phytochrome B in plant responses to
lowtemperature treatment and in aftereffects of chill
ing under light and in darkness remains unexplored.
Elucidation of this question will clarify specific life
features of plants from natural highlatitude habitats
and of plants grown in greenhouses.
The aim of this study was to examine the involve
ment of phytochrome B in cold hardening and
dehardening of plants under light and in darkness.
MATERIALS AND METHODS
Wildtype cucumber (
and the phytochrome Bdeficient mutant (
were used for experiments. The cucumber long hypo
) mutant was obtained form the Laboratory of
Genetics of Wageningen University (the Nether
lands). LopezJuez et al.  reported that
is deficient in phytochrome B.
Cucumber seeds were germinated for 2 days in a
and planted into sandfilled pots.
The pots were watered with a Knop nutrient solution
supplemented with micronutrients (pH 6.2–6.4) and
placed into climatic cabinets with relative humidity of
60–70% at irradiance of 100 W/m
under 16h photoperiod (day/night = 16/8 h) or con
Role of Phytochrome B in the Development of Cold Tolerance
in Cucumber Plants under Light and in Darkness
M. I. Sysoeva
, E. F. Markovskaya
, and E. G. Sherudilo
Institute of Biology, Karelian Branch, Russian Academy of Sciences,
Pushkinskaya ul. 11, Petrozavodsk, Karelia, 185910 Russia;
fax: 7 (8142) 769810; email: email@example.com
Petrozavodsk State University, Petrozavodsk, Karelia, Russia
Received May 12, 2012
—Cold tolerance of cucumber (
L.) seedlings was investigated using wildtype plants
and the phytochrome Bdeficient mutant (
mutant). Plants were subjected for 6 days to intermittent short
term cooling (12
C for 2 h per day) and to continuous chilling under conditions of 16h photoperiod
(day/night = 16/8 h) and permanent illumination. “Dehardening” process was initiated by the transfer of
plants to either light or dark conditions at 23
C. It was concluded that phytochrome B participates in the
development of cold tolerance in cucumber plants under stress conditions, i.e., under shortterm intermittent
chilling at nights and during dehardening in continuous darkness.
Keywords: Cucumis sativus, lh
mutant, shortterm and permanent chilling, continuous illumination, cold tol
erance, phytochrome B
: PLT—permanent low temperature (treatment).