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Triticeae Genomics and Genetics 2011, Vol.2, No.1, 1
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6
http://tgg.sophiapublisher.com
3
between Tibetan triple spikelet wheat and Sichuan
common wheat to mate with cultivated common wheat
Jian 3 and Chuanmai 55 building F
2
populations in
order to analyze the genetic characteristics of triple
spikelet trait and detect the QTL associated with the
triple spikelet trait through SSR markers.
1 Results and Analysis
1.1 Genetic analysis of triple spikelet trait
TTSW
-
5 was mated with Jian 3 and Chuanmai 55 to
generate hybrid F
1
plants of 47 and 11, respectively.
All of F
1
plants self-crossing were to generate F
2
plants of 1107 and 176, respectively. The panicle
phenotypes of F
1
and F
2
were identified in ear
maturity. The results showed that all of F
1
from the
crosses of TTSW
-
5/Jian 3 and TTSW
-
5/Chuanmai 55
exhibit the ear phenotypes of common wheat as the
same as the parents of Jian 3 and Chuanmai 55,
indicating that trait of triple-spikelet of TTSW
-
5
would be controlled by a recessive gene.
F
2
individuals derived from TTSW
-
5/Jian 3 and
TTSW
-
5/Chuanmai 55 were phenotyped in mature ear,
in which 1040 of 1107 individuals of F
2
population from
TTSW
-
5/Jian 3 exhibited the same ear phenotype as
the parental Jian 3, while 67 individuals exhibited the
triple-spikelet-like trait in different levels from
30%~100% of triple–spikelet panicles accounting for
the total spikelets. Likewise, 161 of 176 individuals of
F
2
population from TTSW
-
5/Chuangmai 55 exhibited
the same ear phenotype as the parental Chuanmai 55,
while 15 individuals exhibited the triple-spikelet-like
trait in different levels from 35% to 100% of triple
–spikelet panicles accounting for the total spikelets.
The chi-square test showed that the ratios of two F
2
populations were χ
2
<χ
2
0.05
(χ
2
0.05
=3.841), being
consistent to 15 to 1 (Table 1), which indicated that
triple spikelet traits of TTSW
-
5 should be governed by
two independent genetic recessive genes, this result
was identical to our previous results in genetic analysis
of population derived from Tibet triple spikelet wheat
itself.
Table 1 Segregating distribution of spikelet types in the F
2
populations
Expected segregation
Observed segregation
Combinations
Total
individuals Normal
spikelet
Triple-
spikelet
Normal
spikelet
Triple-
spikelet
χ
2
p
TTSW
-
5/Jian 3
1107
1037.8
69.2
1040
67
0.074
0.75
-
0.90
TTSW
-
5/Chuanmai 55 176
165
11
164
12
0.097
0.75
-
0.90
1.2 Polymorphic analysis among parents and triple
spikelet and common spikelet
944 SSR markers were chosen from the genomes of A,
B and D in common wheat to screen the polymorphisms
between the triple spikelet wheat TTSW
-
5 and Jian 3
of cultivated common wheat, of which 189 markers
were detected to be differences accounting for 20% of
the total markers with well electrophoresis. 69
polymorphic markers were detected in A genome with
7.3% of polymorphic ratio, 66 polymorphic markers
detected in B genome, with 7.0% of polymorphic ratio
and 54 polymorphic markers detected in D genome,
5.7% of polymorphic ratio. 14 of 189 SSR markers
exhibiting polymorphisms between the parents,
including Xgwm377, Xgwm296, Xcfd160, Xcfa2263,
Xwmc144, Xgwm95, Xbarc1064, Xbarc11, Xbarc15,
Xgwm122, Xgwm425, Xgwm275, Xgwm296 and
Xwmc453, showed polymorphisms between the pools
in the triple spikelet and the common spikelet wheat.
1.3 QTL detection
The markers having ploymorphisms in the pools and
parents of the triple spikelet and common spikelet
wheat were applied to scan the F
2
population derived
from TTSW
-
5/Jian 3 for the separation of the triple
spikelet trait. Genetic linkage map of chromosome 2A
were built by 10 SSR markers covering the 112.8 cM
in length of total chromosome (Figure 2). A QTL was
detected in 2A on chromosome 1 by composite
interval mapping analysis with LOD value of 6.19,
tentatively named
qTS2A
-
1
, explaining 33.1% of the
phenotypic variation. The detected QTL was located
between SSR markers, Xgwm275 and Xgwm122, in
span of 6.6 cM in the genetic distance (Figure 1). The