1021-4437/04/5101- © 2004
Russian Journal of Plant Physiology, Vol. 51, No. 1, 2004, pp. 116–119. From Fiziologiya Rastenii, Vol. 51, No. 1, 2004, pp. 130–133.
Original English Text Copyright © 2004 by Kato-Noguchi, Sasaki, Ichii.
Rice seeds are able to germinate and elongate their
coleoptiles under extremely low oxygen conditions,
even under vacuum [1–3]. Germinating rice survived
more than 21 days in N
atmosphere, and metabolic
activity of their coleoptiles was high enough to allow
RNA and protein synthesis [4, 5]. The tolerance of rice
coleoptiles to oxygen deﬁciency was related to the abil-
ity to mobilize the starchy reserves from their
endosperm even under anoxia and to maintain an active
glycolysis leading to ATP production [1, 6–8].
On the other hand, root elongation of rice seeds ger-
minated under anoxia is substantially limited, and the
growth response of rice roots to anoxia was consider-
ably different from that of rice coleoptiles [9, 10]. How-
ever, the biochemical basis for the tolerance of rice
roots to anoxia is not sufﬁciently studied.
Plant root hairs play important roles in the uptake of
nutrients and water because of greater absorptive sur-
face area of roots [11, 12], but the function of root hairs
has not yet been fully understood. In this study, the role
of root hairs of rice seedlings in anoxia tolerance was
investigated on wild type (WT) rice seedlings and root
hair defective mutant
Thus, effects of anoxia on
the growth and activity of alcohol dehydrogenase
(ADH) were determined in coleoptiles and roots of WT
MATERIALS AND METHODS
Seeds of rice (
Oochikara) were mutagenized with 10
azide for 6 h at 20
C and root hair defective mutant
was screened from 60000 M
seedlings [13, 14].
and WT rice were surface sterilized
with 25 mM sodium hypochlorite for 15 min and rinsed
four times in distilled water. Then, the seeds were
allowed to germinate on two sheets of moist ﬁlter paper
(No 1; Toyo Ltd, Japan) in darkness at 25
C in a growth
chamber. After three days, uniform seedlings were
transferred, in groups of 10, to 9-cm petri dishes con-
taining two sheets of ﬁlter paper moistened with 10 ml
of distilled water, and grown for one further day under
the same conditions.
The petri dishes were placed into
gas-changing jars (5 l) at 25
C in the growth chamber
as described by Kato-Noguchi . A stream of N
passed continuously through the jar at 200 ml/min for
48 h. Nonstressed seedlings were supplied with air
ﬂowing at 200 ml/min.
The length of primary roots of rice seedlings was
measured just before and after 48-h anoxic treatment
with a ruler.
Determination of ADH activity.
The primary roots
and coleoptiles of rice seedlings were harvested, frozen
immediately with liquid nitrogen and stored at –80
until extraction. Frozen material was ground to a ﬁne
powder in liquid nitrogen. Then, the powder was
homogenized with ﬁve volumes of ice-cold solution
containing 100 mM Tris–HCl (pH 8.0), 10 mM Na-
ascorbate, 10 mM DTT, 50 mM BSA, and 5% (v/v)
glycerol. The homogenate was centrifuged at 30000
for 30 min. The supernatant was used immediately for
measuring ADH activity spectrophotometrically by
monitoring the oxidation of NADH
at 340 nm as
described by Kato-Noguchi .
Anoxia Tolerance in a Root Hair Defective Mutant of Rice
H. Kato-Noguchi, R. Sasaki, and M. Ichii
Department of Biochemistry and Food Science, Faculty of Agricture, Kagawa University, Miki, Kagawa 761-0795, Japan;
fax: +81-87-891-3086; e-mail: email@example.com
Received October 28, 2002
—Anoxia tolerance of rice (
L.) seedlings was investigated using wild type (WT) and root
hair defective mutant
. The elongation of both
and WT roots was suppressed by anoxia, but this sup-
pression was less in
than in WT roots. The anoxic treatment increased the activity of alcohol dehydroge-
nase in both
and WT roots, but the induction was greater in
roots. These results suggest that anoxia
roots is greater than that of WT roots, indicating that root hairs may interfere with the anoxia
tolerance of rice roots.
Key words: Oryza sativa - anoxia - alcohol dehydrogenase - mutant - tolerance - root hair
: ADH—alcohol dehydrogenase; WT—wild type.
This article was submitted by the authors in English.