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Molecular Plant Breeding 2011, Vol.2, No.9, 60
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mene.org/), the syntenic region of sorghum GFa in
maize is a 313 kb on maize chromosome 3 (zC3),
while the syntenic region of sorghum GFb in sorghum
is a 64 kb and 131 kb on maize chromosome 6 (zC6)
and chromosome 8 (zC8), respectively. In maize, the
GFa contains 11 putative protein-coding genes (from
GRMZM2G099166_T02, a DUF581 family protein,
to GRMZM2G116282_T02, a RNA-binding protein),
while the GFb on zC6 contains 6 putative protein-
coding genes (from GRMZM2G033971_T01, a
DUF212 family protein, to GRMZM2G043035_T02,
an Ole e
Ⅰ
family protein), and on zC8 contains 6
putative protein-coding genes (from GRMZM2G044-
866_T01, a DUF616 family protein, to GRMZM2G1-
21117_T02, a hypothetical protein) (http://rapdb.dna.
affrc.go.jp/viewer/gbrowse/build4/) (supplement and
Figure 2). There are 11 orthologous genes in GFa
between in the rice and sorghum genome. There are 6
orthologous genes respectively in GFb on maize
chromosome 6 and 8 between in the maize and
sorghum genome. The ZmSS
Ⅳ
b was located between
a hypothetical protein and a DUF212 family protein
(supplement and Figure 2). Moreover, we can not
found the
SS
Ⅳ
a
gene on chromosomr 3 regions in
maize, and the chlorophyll a-b binding protein and the
Serine acetyltransferase 3 also lost. These results
strongly suggested that the
SS
Ⅳ
a
gene was lost in
sorghum and maize genomes during their evolution.
1.4 Organ expression profile of the
SS
genes in
sorghum and wheat
Expression divergence was often the first step in the
functional divergence between duplicate genes, thus
increasing the chance of retention of duplicated genes
in a genome (Force et al., 1999). To define the
function of the deteced
SS
genes, we investigated their
expression in root, leaf and developing endosperm
using RT-PCR in sorghum and wheat. The results
indicated that the
SbGBSS
Ⅰ
,
SbSS
Ⅱ
a
and
SbSS
Ⅲ
a
genes were expressed mainly in endosperms, while the
SbGBSS
Ⅱ
,
SbSS
Ⅱ
b
, and
SbSS
Ⅲ
b
genes mainly in
leaf in sorghum. The
SbSS
Ⅰ
,
SbSS
Ⅱ
c
and
SbSS
Ⅳ
genes were constitutively expressed in sorghum. In
addition, the
SbGBSS
Ⅱ
and
SbSS
Ⅲ
b
genes were also
highly expressed in roots (Figure 3A).
TaSS
Ⅱ
b
and
TaSS
Ⅲ
b
were mainly expressed in leaves, and
moderately in roots and the early stage endosperms
(Figure 3B).
Figure 3 The organ expression analysis of
SS
genes in sorghum
and wheat
Note: A: RT-PCR analysis of the expression of
SS
genes in
sorghum; B: RT-PCR analysis of the expression of
SS
Ⅱ
b
and
SS
Ⅲ
b
genes in wheat; Thermocycling time and temperature are
as follows: 95
℃
for 5 min, followed by indicated cycles of
95
℃
for 30 s, respective annealing temperature (Table 2; Table
3) for 30 s, 72
℃
for 40 s, and a final extension period 72
℃
for
7 min; Lower panel shows the loading control of an Actin
(X79378 of sorghum and AY663392 of wheat) transcripts in
each sample. DAF, days after flowering
The mRNA for the
TaSS
Ⅱ
a
was expressed in leaves
and endosperms under the conditions used (Li et al.,
1999a), but the SGP-B1 (TaSS
Ⅱ
a) protein was not
detected in leaf using monoclonal antibodies
(Shimbata et al., 2005). This result is similar to the
findings of OsSS
Ⅱ
a in rice that the transcripts could
be tested at a lower level in leaf, but its proteins could
not be detected in leaf soluble or starch granule
extracts using polyclonal antibodies (Jiang et al.,
2004). The expression of TaSS
Ⅱ
b and TaSS
Ⅲ
b was
mainly in leaves and roots, but lower in filling stage
endosperms, suggests that TaSS
Ⅱ
b and TaSS
Ⅲ
b
mainly function in leaves and roots, while TaSS
Ⅱ
a
and TaSS
Ⅲ
a in endosperms as those in maize and rice
(Jiang et al., 2004; Yan et al., 2009). These results
indicated SS duplicators were also diverged in