Basic HTML Version
Molecular Plant Breeding 2010, Vol.1 No.3
http://mpb.sophiapublisher.com
Page 3 of 6
The confirmed 241 recessive plants of F
2
population
were used to construct the linkage map of the gene of
red grain color; the genetic distance between
R-D1
gene
and SSR loci was analyzed by Mapmaker 3.0b. Eight
polymorphic SSR markers were employed to screen the
241 recessive plants, and five SSR markers (Xgwm3,
Xgwm314, Xgwm664, Xwmc552 and Xbarc270)
showed close linkage to
R-D1
gene (Table 2, Figure 1).
The
R-D1
gene in Chuanmai 42 linked closely with
markers Xgwm3 and Xgwm314 with 2.1 cM and 2.5 cM
genetic distance, respectively (Figure 1).
Figure 1
Linkage map involving the
R-D1
gene constructed
with five SSR markers on chromosome 3DL
Note: Locus names are indicated on the right side of the map;
Kosambi map distances (cM) are shown on the left side; A:
Homozygote for the allele from Chuanmai42; B: Homozygote
for the allele from CW565; H: Heterozygote carrying both
alleles from Chuanmai42 and CW565; C: Not homozygote and
heterozygote for the allele from Chuanmai42 and CW565
2 Discussion
Chuanmai 42, a wheat cultivar with high-yield
potential, was developed by using a red grain color
synthetic hexaploid wheat (Syn769,
durum
wheat
Decoy1 (white grain color)×
Ae.tauschii
SQ-188 (red
grain color)) crossed and backcrossed with two white
grain color local wheat varieties. According to the
pedigree, the character of red grain color of Chuanmai
42 derived from the D genome donor
Ae.tauschii
SQ-188 of Syn769. The red grain color was dominant
to white, and the alleles conferring red grain color
were denoted as
R-A1b, R-B1b
and
R-D1b
,and alleles
conferring white grain color as
R-A1a, R-B1a
and
R-D1a
. The character of red grain color in Chuanmai
42 was controlled by a single gene, so the red grain
color alleles conferring Chuanmai42 were
R-A1a,
R-B1a
and
R-D1b
. Chuanmai42 is becoming a popular
cultivar and an important breeding parent in China
because of a high and stable yield potential, despite
having a red grain color while white is preferred.
To date, R-A1, R-B1 and R-D1 were mapped by RFLP,
STS and EST marker. Previous mapping efforts
showed that R genes were mapped by orthologous
alleles of RFLP markers on the long arm of
chromosome 3D, 3A and 3B (Flintham and Humphrey,
1993; Gale et al., 1995; Nalam et al., 2006;
Kuraparthy et al., 2008), and R-D1 gene closely
linked with RFLP markers Xbcd131 and Xabc174 on
the long arm of chromosome 3D. R-A1 was mapped
within an interval of 4.4 cM flanked by one STS
marker and one EST marker (Kuraparthy et al., 2008).
R-A1, R-B1 and R-D1 were also mapped by SSR
(Sherman et al., 2008; Imtiaz et al., 2008; Groos et al.,
2002), and R-D1 gene tightly linked to SSR markers
Xgwm4306 (a distance of 3.2 cM) (Sherman et al.,
2008) and Xgwm1200 (a distance of 5.0 cM) (Imtiaz
et al., 2008). In present paper, the R-D1 gene derived
from D genome donor of synthetic hexaploid wheat
was also successfully mapped on the long arm of
chromosome 3D within an interval of 4.6 cM flanked
by SSR markers Xgwm3 and Xgwm314, with genetic
distance of 2.1 cM and 2.5 cM, respectively. The SSR
markers to R-D1 (Xgwm3 and Xgwm314) in our
population were more tightly linked than reported
previously.
Table 2 Linkage analysis of Red-grain-color gene
R-D1
with five polymorphic SSR markers in 241 recessive plants of F
2
population
SSR maker
No. of plants
A
B
H
C
Xgwm3
-
3D
241
1
232
8
0
Xgwm314
-
3D
241
3
232
6
0
Xwmc552
-
3D
241
8
216
17
0
Xgwm664
-
3D
241
9
201
30
1
Xbarc270
-
3D
241
5
226
10
0