ISSN 1021-4437, Russian Journal of Plant Physiology, 2006, Vol. 53, No. 2, pp. 198–204. © MAIK “Nauka /Interperiodica” (Russia), 2006.
Published in Russian in Fiziologiya Rastenii, 2006, Vol. 53, No. 2, pp. 220–226.
Desiccation tolerance is the capability acquired dur-
ing seed development and lost during germination,
often referring to the ability to survive below the mois-
ture content of 5–7%. The capacity of tolerating
ultradrying, i.e., of preventing a number of detrimental
effects, differs among various seeds. Desiccation toler-
ance is probably a quantitative feature associated with the
accumulation of proteins, lipids, and carbohydrates .
Desiccation tolerance is related to the development
phase, hydration level, type of seeds, and the accumu-
lation of protectants. Sugars contribute to the stability
of membranes, proteins, and the cytoplasmic glassy
matrix, playing the protective role in the seed during
desiccation . It was suggested that the accumulation
of sugars, including nonreducing sugars and cyclitols,
favored the stabilization of membrane structure and
proteins in the absence of water. We investigated the
relationship between the acquisition of desiccation tol-
erance to ultradrying and various sugars during seed
development and maturation.
MATERIALS AND METHODS
L.) seeds from Japonica type
(cvs. Chunjiang 683 and Chunjiang 15), Indian type
(cvs. J174 and Zhongzu 1), Waxy type (cv. Zhongx-
iangnuo), and Hybrid type (cv. Shanyou 63) were har-
vested in 1999–2001 by China National Rice Research
Institute. Initial moisture contents (MC) of seeds
ranged from 10.5 to 11.1%. Initial germination percent-
ages were greater than 95% for all cultivars except
Chunjiang 15 rice (92%).
For each development stage studied, seeds of Indian
type (cv. Zhongzu 1) and Japonica rice (cv. Chunjiang 15)
were regularly collected until seed matured.
Desiccation tolerance test.
To test the ability of
seeds to tolerate desiccation, samples of 150 to 200
immature or mature seeds were dried rapidly over a sat-
urated LiCl solution at 25
C to a ﬁnal moisture content
of 10%. After six days, seeds were then humidiﬁed
overnight at 98% RH and tested for ability to germinate
on two layers of ﬁlter paper with distilled water in 9-cm
petri dishes (100 seeds per dish, 4 replicates) in dark-
ness at 25
All seeds were ultradried from moisture content of
11–10% to as low as 3.5% by storing them in a desic-
cator with activated silica gel (silica gel : seed weight
ratio = 10 : 1) for 1 to 3 weeks at 25
C and replaced by
dried silica gel every day, and then weighed samples at
Changes in Sugars
during Rice Seed Desiccation
C. Zhu, L.-P. Li, and X. Liu
State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University,
Hangzhou, 310029, China;
fax: +86-571-86971634; e-mail: firstname.lastname@example.org
Received April 7, 2005
—The correlation between desiccation tolerance and soluble sugars was investigated in seeds of a
number of rice cultivars belonging to the Asian rice
They were dried or ultradried to various
low moisture content and then imbibed for germination testing. Few or no changes on germination percentage
and vigor index were found in Indian rice seeds even after their moisture content fell to 3.5%, indicating that
Indian rice exhibited a strong desiccation tolerance. On the contrary, Japonica rice seed germination percentage
rapidly decreased, after their moisture content fell to 4.5%. The capacity for desiccation tolerance in Japonica
(cv. Chunjiang15) and Indian (cv. Zhongzu1) developing seeds increased on 23–40 and 15–25 days after pol-
lination, respectively. Though the level of monosaccharides declined, the content of sucrose has increased dur-
ing desiccation. These results suggest that desiccation tolerance might be associated with the increase in seed
viability and the changes in sugar level, and that rafﬁnose could be capable of contributing to the desiccation
tolerance to ultradrying.
Key words: Oryza sativa - seeds - development and maturation - ultradrying - desiccation tolerance - soluble
sugars - rafﬁnose - moisture content
: DAP—days after pollination; MC—moisture con-
tent; VI—vigor index; GI—germination index.
The text was submitted by the authors in English.