ISSN 1021-4437, Russian Journal of Plant Physiology, 2007, Vol. 54, No. 4, pp. 472–479. © Pleiades Publishing, Ltd., 2007.
Published in Russian in Fiziologiya Rastenii, 2007, Vol. 54, No. 4, pp. 534–541.
Tobacco plants are generally drought-tolerant, but
can be rather sensitive to water deﬁcit during rapid
growth and leaf expansion time. Drought stress decel-
erated tobacco growth, shortened plant stem, and
reduced leaf area, especially during the rapid growth
stage . The strategies have to be developed for the
improvement of tobacco drought resistance.
Glycinebetaine (N,N',N"-trimethylglycine, GB) is a
quaternary ammonium compound accumulating in a
wide variety of organisms that survive in arid or high-
salt environments. GB is a nontoxic cellular compatible
solute that decreases osmotic potential inside cell
exposed to stress-induced hypertonic conditions [2, 3].
Moreover, GB is more effective than other compatible
solutes in stabilizing the membrane integrity, enzymes,
and functional units (e.g., the oxygen-evolving PSII
complex and Rubisco) [4–6]. The protective capacity of
GB under various stress conditions has prompted
numerous investigations in order to increase GB con-
tent in plants. So far, a number of transgenic plants
were obtained, especially among GB natural nonaccu-
mulators including tobacco, that exhibited various lev-
els of GB accumulation and stress tolerance [5, 7, 8].
However, the GB level in most plants was far below the
level in natural accumulators due to, among other fac-
tors, a deﬁciency of endogenous choline, a precursor of
GB [9, 10]. Our strategy of increasing GB accumula-
tion to improve stress tolerance in tobacco plants has
focused on exogenous application of GB.
In this paper, two tobacco cultivars differing in
drought tolerance were used to study the effects of
foliar-applied GB on growth, and to discuss the possi-
ble physiological mechanisms of GB protective func-
MATERIALS AND METHODS
Preparation and treatment of tobacco cultivars.
Two tobacco (
drought-tolerant DHJ5210 and drought-sensitive
ZY100, were offered by the Department of Tobacco
Science of Shandong Agricultural University (China).
Seeds germinated in a plastic tray containing a mixture
of organic fertilizer and soil. When the 4th leaf was
expanded, the seedlings were transplanted into pots
Glycinebetaine Application Ameliorates Negative Effects
of Drought Stress in Tobacco*
X. L. Ma, Y. J. Wang, S. L. Xie, C. Wang, and W. Wang
College of Life Science and College of Plant Protection, State Key Laboratory of Plant Biology of Shandong,
Shandong Agricultural University, Tai’an, Shandong, 271018 China;
Received August 24, 2006
—Two tobacco (
L.) cultivars differing in drought tolerance were used to study the
effects of foliar-applied glycinebetaine (GB, 80 mM) under well-watered and water-deﬁcit conditions. The lat-
ter affected shoot biomass and height, with a more signiﬁcant decrease observed in drought-sensitive cultivar
than in drought-resistant cultivar. Foliar-applied GB was absorbed, accumulated by tobacco leaves and
improved growth of plants subjected to water deﬁcit. GB-treated plants maintained leaf water status apparently
due to the improved osmotic adjustment. GB application enhanced the photosynthesis in water-deﬁcit experi-
encing plants, mostly due to a greater stomatal conductance and carboxylation efﬁciency of
photosystem II (PSII) activity in GB-treated plants was higher, as suggested by higher actual efﬁciency of PSII
PSII). GB increased anti-oxidative enzyme activities under water deﬁcit. All these effects resulted in an
improved shoot biomass and height. Therefore, foliar GB application at the rapid growth stage favors plant
growth in drought-stressed plants, mainly by improving water status and increasing PSII activity.
Key words: Nicotiana tabacum - antioxidant enzymes - photosynthesis - ion content - reactive oxyhen species -
: ASA—ascorbic acid; APX—ascorbate peroxi-
dase; CAT—catalase; Ci—intercellular CO
GB—glycinebetaine; Gs—stomatal conductance; MDA—malon-
—net photosynthesis rate; POD—peroxidase;
ROS—reactive oxygen species; RWC—relative water content;
SOD—superoxide dismutase; PSII—photosystem II;
actual PSII efﬁciency.
*The text was submitted by the authors in English.