ISSN 1021-4437, Russian Journal of Plant Physiology, 2009, Vol. 56, No. 4, pp. 575–579. © Pleiades Publishing, Ltd., 2009.
Published in Russian in Fiziologiya Rastenii, 2009, Vol. 56, No. 4, pp. 635–640.
Cadmium is a highly toxic and persistent environ-
mental heavy metal for plants and animals . It is eas-
ily taken up by plant roots and translocated to shoot. A
high Cd accumulation generally causes a growth inhi-
bition and even a plant death due to damaging some
enzyme activities, photosynthesis, respiration, transpi-
ration, and nutrient uptake [1, 2 ].
Glutathione (GSH) is the major nonprotein thiol
with many functions in plant metabolism. It is involved
in a detoxiﬁcation of some heavy metals [3, 4]. An Ara-
bidopsis mutant with a reduced capacity to produce
, is hypersensitive to both Cd and copper .
However, elevation of GSH does not always correlate
with enhanced tolerance to heavy metals , perhaps
because GSH alone is not always sufﬁcient to support a
complex mechanism of the tolerance to any heavy
metal-induced stress  that involves heavy metal
pumping out cytosol, or chelating, binding to various
thiol compounds in the cytosol, and sequestering into
vacuoles. Other antioxidative and repair mechanisms
may also participate in the process .
The nonprotein amino acid
(BABA) plays some roles in plant defense responses
[9–12]. In some cases, BABA acts via salicylic acid-
dependent defense mechanism in Arabidopsis . In
This text was submitted by the authors in English.
other cases, BABA potentiates abscisic acid-dependent
signaling . In addition, BABA, being rarely found
in plants, can protect
plants against abiotic
stresses such as drought, high salinity [9, 10], and heat
stress . However, it remained unclear whether it
plays a role in tolerance to Cd in Arabidopsis. In this
study, we had examined the protective role of BABA in
the case of Cd induced stress in Arabidopsis.
MATERIALS AND METHODS
Plant material and growth conditions.
wild-type ecotype Colombia-0
were surface-sterilized and plated on Murashige and
Skoog media  containing 1% sucrose. After 3 days
in the dark at
, the plates were placed in a growth
s) light intensity under
long-day conditions (16 h light/8 h dark). For planting,
seeds were sowed in pots with soil consisting of peat
soil : vermiculite : perlite = 3 : 9 : 0.5 presoaked with
plant nutrient medium . Plants were grown in a
growth room at
s) light inten-
sity and photoperiod of 16 h light.
Treatments and Cd tolerance test.
growth conditions, seedlings grown on MS media for
5 days were pretreated with water or 200
(Sigma, United States) by incubating their roots for
1 day, and six-day-old seedlings were then grown ver-
tically on 0.5 MS agar plates, with or without 100 or
(Sigma). After 4 days of growth, some
plants had been sampled for measuring root length, Cd
The Role of
-Aminobutyric Acid in Enhancing Cadmium
S. Q. Cao, G. Ren, L. Jiang, H. B. Yuan, and G. H. Ma
School of Biotechnology and Food Engineering, Hefei University of Technology,
193 Tunxi Road, Hefei, Anhui, 230009 China;
Received November 25, 2007
—An inhibition of the root growth of Arabidopsis plants subjected to cadmium-induced stress was
signiﬁcantly alleviated by
-aminobutyric acid (BABA) pretreatment. There was no signiﬁcant difference in Cd
content between BABA-pretreated and BABA-untreated plants under Cd stress. Treatment with buthionine sul-
foximine, an inhibitor of glutathione (GSH) biosynthesis, abolished BABA-mediated enhanced Cd tolerance.
In addition, the transcript levels of
in BABA-treated plants were somewhat higher than
those of water-treated plants subjected to Cd stress. Our results suggest that BABA protects Arabidopsis against
Cd stress through a GSH-dependent pathway.
Key words: Arabidopsis -
-aminobutyric acid - cadmium tolerance - glutathione
-amino-butyric acid; BSO—buthionine