ISSN 10214437, Russian Journal of Plant Physiology, 2011, Vol. 58, No. 3, pp. 538–542. © Pleiades Publishing, Ltd., 2011.
Fisch.) is a very
popular medicinal plant, which roots contain glycyr
rhizic acid and liquiritin mainly accumulated in the
root and rhizome tissues [1, 2]. Recently, glycyrrhizic
acid has been found to be highly active in inhibiting
the replication of the severe acute respiratory syn
drome (SARS)associated virus and has been sug
gested as a potential therapeutic agent for chronic
hepatitis and acquired immunodeficiency syndrome
(AIDS) . Licorice plants appear to be highly
droughttolerant, being a favorable plant to restore
degraded desert, arid and semiarid ecosystems of
northwest China . However, data on physiological
processes, such as biomass production and secondary
metabolite yield, in response to environmental condi
tions are lacking .
Water deficit usually inhibits plant growth and pro
ductivity by affecting gas exchange and especially pho
tosynthesis [6, 7]. Water use efficiency (WUE) can be
traditionally defined as the ratio of net photosynthesis
to transpiration over a period of seconds or minutes
. The higher WUE has been mentioned as a strategy
This text was submitted by the authors in English.
to improve crop performance under waterlimited
conditions . However, in licorice plants photosyn
thesis and biomass production as well as WUE in
response to water deficit were not studied.
Water deficit can induce the biosynthesis of some
secondary metabolites [10–12], resulting in their
accumulation in medicinal plants [10, 13, 14]. For
example, the concentration of rutin and chlorogenic
acid increased with drought severity in tomato plants
. Although the responses of the metabolites to
drought have been investigated in some medicinal
plants [4, 10], no reference concerning the effect of
various water deficit levels on their production by lic
orice roots is available.
The present study aims to determine the effect of
water deficit on gas exchange, biomass and secondary
metabolites production in licorice plants. It was
hypothesized that a suitable water deficit, in addition
to saving water, can also increase the amount of root
secondary metabolites without negative effect on root
MATERIALS AND METHODS
Plants and experimental design.
was performed in a greenhouse at Beijing University of
Chinese Medicine. Seeds were collected from one
Effect of Water Deficit on Biomass Production
and Accumulation of Secondary Metabolites
in Roots of
W. D. Li
, J. L. Hou
, W. Q. Wang
, X. M. Tang
, C. L. Liu
, and D. Xing
School of Chinese Pharmacy, Beijing University of Chinese Medicine, Beijing, 100102 China;
Engineering Research Center of Good Agricultural Practice for Chinese Crude Drugs, Beijing, China
School of Traditional Chinese Medicine, Capital Medical University, Beijing, China
Received October 27, 2009
—Twoyearold seedlings of licorice plant (
Fisch) were exposed to three
degrees of water deficit, namely weak (60–70%), moderate (40–50%), and strong (20–30%) relative water
content in soil, whereas control plants were grown in soil with 80–90% water content. Moderate and strong
water deficit decreased the net photosynthetic rate, stomatal conductance, and biomass production. Water
use efficiency and the roottoshoot ratio increased significantly in response to water deficit, indicating a high
tolerance to drought. Weak water deficit did not decrease root biomass production, but significantly increased
the production of glycyrrhizic acid (by 89%) and liquiritin (by 125%) in the roots. Therefore, a weak water
deficit can increase the yield of root medical compounds without negative effect on root growth.
Keywords: Glycyrrhiza uralensis,
biomass production, gas exchange, glycyrrhizic acid, liquiritin, water deficit.
: WC—water content; WUE—water use efficiency.