The b-conglycinin deﬁciency in wild soybean is associated
with the tail-to-tail inverted repeat of the a-subunit genes
Received: 19 April 2011 / Accepted: 23 November 2011 / Published online: 23 December 2011
Ó Springer Science+Business Media B.V. 2011
Abstract b-Conglycinin, a major seed protein in soy-
bean, is composed of a, a
, and b subunits sharing a high
homology among them. Despite its many health beneﬁts,
b-conglycinin has a lower amino acid score and lower
functional gelling properties compared to glycinin, another
major soybean seed protein. In addition, the a, a
, and b
subunits also contain major allergens. A wild soybean
(Glycine soja Sieb et Zucc.) line, ‘QT2’, lacks all of the
b-conglycinin subunits, and the deﬁciency is controlled by
a single dominant gene, Scg-1 (Suppressor of b-conglyci-
nin). This gene was characterized using a soybean cultivar
‘Fukuyutaka’, ‘QY7-25’, (its near-isogenic line carrying
the Scg-1 gene), and the F
population derived from them.
The physical map of the Scg-1 region covered by lambda
phage genomic clones revealed that the two a-subunit
genes, a b-subunit gene, and a pseudo a-subunit gene were
closely organized. The two a-subunit genes were arranged
in a tail-to-tail orientation, and the genes were separated by
197 bp in Scg-1 compared to 3.3 kb in the normal allele
(scg-1). In addition, small RNA was detected in immature
seeds of the mutants by northern blot analysis using an
RNA probe of the a subunit. These results strongly suggest
that b-conglycinin deﬁciency in QT2 is controlled by post-
transcriptional gene silencing through the inverted repeat
of the a subunits.
Keywords Glycine max Á Glycine soja Á b-Conglycinin Á
Inverted repeat Á Gene silencing
b-Conglycinin (7S globulin) and glycinin (11S globulin)
are the major seed storage proteins in soybean. b-Con-
glycinin is composed of three subunits, a, a
, and b, which
share signiﬁcant homology. The a subunit (Gly m Bd
60 K) was identiﬁed as an allergenic protein (Ogawa et al.
1995). The a
and b subunits were also identiﬁed as
potential allergens by immunoblot analysis (Krishnan et al.
2009). Because sulfur amino acid content is lower in
b-conglycinin than in glycinin, it has been suggested that
the amino acid score of soybean protein could be improved
Accession numbers Fukuyutaka alpha-IR 10.2 kb AB604030.
QY7-25 Scg-1 region 31.6 kb AB604031.
-1 of Fukuyutaka AB610665.
CG-b-1 of Fukuyutaka AB610666.
CG-b-1 of QY7-25 AB610667.
Electronic supplementary material The online version of this
article (doi:10.1007/s11103-011-9865-y) contains supplementary
material, which is available to authorized users.
Y. Tsubokura Á S. Watanabe Á A. Kaga Á Y. Katayose Á
M. Ishimoto Á K. Harada (&)
National Institute of Agrobiological Sciences, 2-1-2 Kannondai,
Tsukuba, Ibaraki 305-8602, Japan
Y. Tsubokura Á M. Hajika
National Institute of Crop Science, 2-1-18 Kannondai, Tsukuba,
Ibaraki 305-8518, Japan
SNOW BRAND SEED CO., LTD, Chiba Research Station, 634,
Naganumaharacho, Inage, Chiba 263-0001, Japan
Institute of the Society for Techno-Innovation of Agriculture,
Forestry and Fisheries, 446-1 Ippaizuka, Kamiyokoba, Tsukuba,
Ibaraki 305-0854, Japan
Northeast Institute of Geography and Agroecology,
Chinese Academy of Sciences, Harbin 150081, China
Plant Mol Biol (2012) 78:301–309