ISSN 1021-4437, Russian Journal of Plant Physiology, 2009, Vol. 56, No. 5, pp. 709–715. © Pleiades Publishing, Ltd., 2009.
Published in Russian in Fiziologiya Rastenii, 2009, Vol. 56, No. 5, pp. 783–790.
High-oil maize is deﬁned as special maize with
more than 6% oil concentration in the grain . Com-
pared with normal maize (4% of oil concentration), it
has reduced-size endosperm and a larger germ (scutel-
lum and embryo) and 85% of the oil is stored in the
germ . The use of high-oil maize not only improves
feed conversion, but also reduces the amount of supple-
mental fats needed in livestock feed because of its
higher caloric content and better protein quality [3, 4].
However, high-oil maize lines were produced by
human long-term selection. In 1896, Hopkins ﬁrst ini-
tiated the Illinois long-term selection experiment with
Burr’s White Variety for the purpose of investigating
whether breeding and selection could improve kernel
composition, such as protein and oil concentrations .
After 100 generations of selection, the oil concentration
of Illinois High-oil maize reached 20.37% . In
China, Song et al.  developed a number of high-oil
maize populations after 1980. These include Beijing
High Oil (BHO) derived from a synthetic with elite
Chinese normal lines, the oil concentration of which
increased from 4.71 to 13.9% after 15 cycles. These
populations were employed to develop elite high-oil
This text was submitted by the authors in English.
lines that were used to produce Chinese high-oil maize
In plants, stearoyl-acyl carrier protein desaturase
(SAD), commonly known as
the ﬁrst double bond into stearoyl-ACP between car-
bons 9 and 10 to produce oleoyl-ACP (stearic acid con-
version into oleic acid) . Expression and regulation
of SAD in plants have been studied extensively [8, 9].
Fofana et al.  found that SAD was most highly
expressed in ovaries of ﬂax (
its expression was modulated during seed development.
Knutzon et al.  down-regulated the SAD activity of
rapeseed and resulted in the reduction of oil content in
transgenic seeds and their low germination rate . To
our knowledge, SAD expression in high-oil and normal
maize inbred lines has not been described.
In this study, we identiﬁed the expression of SAD in
high-oil and normal maize and found that it was signif-
icantly more abundant in high-oil maize than in normal
maize not only at the protein and mRNA levels but also
at the product level.
MATERIALS AND METHODS
Two maize inbred lines, By804 and
B73, were used as plant material for proteome and lipid
analyses. By804 is a high-oil inbred line containing
11.78% oil, which was selected from the Beijing High
Oil (BHO) population, whereas B73 is a normal inbred
line with 3.45% oil in the grain at maturity. These
SAD, a Stearoyl-Acyl Carrier Protein Desaturase Highly
Expressed in High-Oil Maize Inbred Lines
Zh. J. Liu
, X. H. Yang
, and Y. Fu
Hi-Tech Research Centre, Shandong Academy of Agricultural Sciences, Jinan, 250100 China;
fax: 086-0531-8317-8156; e-mail: firstname.lastname@example.org
National Maize Improvement Center of China, China Agricultural University, Beijing, 100094 China
Received January 24, 2008
—As special maize with more than 6% oil concentration in the grain, high-oil maize has received
increased interest recently. To date, little is known about the expressions of genes involved in fatty acid metab-
olism of high-oil maize. Stearoyl-acyl carrier protein desaturase (SAD) is a key enzyme that converts stearic
acid to oleic acid. In this study, two-dimensional electrophoresis, gas chromatography, and real-time PCR were
used to determine the expressions of SAD at three seed development stages in high-oil and normal maize inbred
lines. SAD was signiﬁcantly more abundantly expressed in high-oil maize than in normal maize, not only at the
protein and mRNA levels, but also at the product level. These results suggested that a high expression of SAD
may play an important role in increasing oil concentration in high-oil maize.
Key words: high-oil maize - SAD - 2-DE - gas chromatography - real-time PCR
: ACP—acyl carrier protein; DAP—days after pol-
lination; 2-DE—two-dimensial electrophoresis; SAD—stearoyl-
acyl carrier protein desaturase; QTL—quantitative trait locus.