Basic HTML Version
Legume Genomics and Genetics (online), 2010, Vol. 1, No.8, 41-46
http://lgg.sophiapublisher.com
low availability to map the resistance gene. Recently,
Li et al. (2006) and Bai et al. (2009) located the SC-14,
SC
-
11 resistance genes on linkage group F, and found
the SSR markers closely linked to the resistance genes,
respectively. But there hasn’t reports on molecular
marker assisted selection for SMV resistance genes yet.
In this paper, we determined the inheritance mode of
resistance to strain SC
-
12 in Qihuang22, identified mo-
lecular markers linked to the resistance gene, located
the resistance gene on the soybean genetic linkage
map, and verified MAS efficiency of the markers
closely linked to the resistance gene in order to provide
theory and method guidance for the resistance breeding
programs to SMV and resistance genes pyramiding.
1 Results
1.1 Inheritance of resistance to SMV strain SC
-
12
in soybean
The inoculation reaction results showed that Qihuang22
and F
1
from the cross Qihuang22×Nannong1138
-
2
displayed resistance to the SMV strain SC
-
12, while
Nannong1138
-
2 was susceptible. F
2
segregation po-
pulation exhibited a good fit to the expected ratio of 3
resistant (R): 1 susceptible (S), and F
2:3
lines seg-
regated with an acceptable fitness to 1 R: 2 seg-
regating: 1 S (Table 1). These results indicated that a
single dominant gene, designated as
R
SC-12
, controlled
resistance to the strain SC
-
12 in Qihuang22.
1.2 Gene mapping of
R
SC
-
12
with SSR markers
7 SSR markers, Sat_297, Sat_234, Sat_154, SOYH-
SP176, Satt114, Satt334 (Figure 1) and Sct_033,
which presented polymorphic between Qihuang22 and
Nannon1138
-
2 as well as the resistant and susceptible
bulks, were identified based on the bulk segregant
analysis (BSA). The 7 markers showed a good fitness
to 1:2:1 ratio in the F
2
segregation population by χ
2
tests (Table 2). Furthermore, analysis of linkage by
using software MAPMAKER
/
EXP 3.0b indicated
that the 7 markers were all linked to the resistance
gene
R
SC-12
and
R
SC-12
was located on linkage group F
based on the soybean integrated linkage map by Song
Figure 1 Analysis for genotype of SSR marker Satt334 closely
linked to
R
SC-12
in F
2
population of Qihuang×Nannong1138
-
2
Note: P
1
: Qihuang22; P
2
: Nannong1138
-
2; B
R
: Resistant bulk;
B
s
: Susceptible bulk; The arrow indicates the band specific to
the resistance phenotype
Table1 Segregation analysis of reaction to SMV strain SC
-
12 in Qihuang22×Nannong1138
-
2
No. of plants or families
Generation
Total
Resistant
Segregating
Susceptible
Expected ratio
χ
2
P
Qihuang22 (P
1
)
34
34
0
F
1
16
16
0
F
2
219
164
55
3R:1S
0.002
0.969
F
2:3
126
27
67
32
1R:2Seg.:1S
0.905
0.636
Nannong1138
-
2 (P
2
) 36
0
36
Table 2 Segregation analyses for molecular markers closely linked to
R
SC-12
in a F
2
population from the cross of Qihuang22 and
Nannong1138
-
2
Observed No.
Marker
No. of F
2
population
RR
Rr
rr
Expected ratio χ
2
P
Sat_297
218
54
106
58
1:2:1
0.312
0.856
Sat_234
219
56
112
51
1:2:1
0.342
0.843
Sat_154
219
56
105
58
1:2:1
0.406
0.816
SOYHSP176
219
58
104
57
1:2:1
0.562
0.755
Satt114
218
57
103
58
1:2:1
0.670
0.715
Satt334
219
58
102
59
1:2:1
1.037
0.596
Sct_033
219
57
104
58
1:2:1
0.562
0.755
Note: RR: Banding pattern tested by SSR marker consistent with the one of the R parent; Rr: Consistent with the one of F
1
; rr:
Consistent with one of the S parent; The followings are the same
42