全 文 ：Journal of Genetics and Genomics
(Formerly Acta Genetica Sinica)
July 2007, 34(7): 623-633
Received: 2006-12-27; Accepted: 2007-02-07
This work was supported by the Hi-Tech Research and Development (863) Program of China (No. 2006AA10Z1F6), Hi-Tech Re-
search of Jiangsu Province (No.BG2005310), the Program for Changjiang Scholars and Innovative Research Team in University
(No.10418) (PCSIRT) and the Innovation Foundation of Young Science and Technology of Nanjing Agriculture University, and the
Introduction of Talents Foundation of Nanjing Agriculture University.
① Corresponding author. E-mail: xiuew@njau.edu.cn; Tel: +86-25-8439 5344
www.jgenetgenomics.org
Research Article
Assessment of Genetic Diversity of Yunnan, Tibetan, and
Xinjiang Wheat Using SSR Markers
Haiyan Wang, Xiu’e Wang①, Peidu Chen, Dajun Liu
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Institution of Cytogenetics, Nanjing Agricultural University, Nanjing 210095,
China
Abstract: A total of 206 SSR (Simple Sequence Repeats) primer pairs were used to detect genetic diversity in 52 accessions of
three unique wheat varieties of western China. A total of 488, 472, and 308 allelic variants were detected in 31 Yunnan, 15 Tibetan
and 6 Xinjiang wheat accessions with an average of PIC values 0.2764, 0.3082, and 0.1944, respectively. Substantial differences in
allelic polymorphisms were detected by SSR markers in all the 21 chromosomes, the 7 homoeologous groups, and the three ge-
nomes (A, B, and D) in Yunnan, Tibetan, and Xinjiang wheat. The highest and lowest allelic polymorphisms in all the 21 chromo-
somes were observed in 3B and 1D chromosomes, respectively. The lowest and highest allelic polymorphisms among the seven
homoeologous groups was observed in 6 and 3 homoeologous groups, respectively. Among the three genomes, B genome showed
the highest, A the intermediate, and D the lowest allelic polymorphism. The genetic distance (GD) indexes within Yunnan, Tibetan,
and Xinjiang wheat, and between different wheat types were calculated. The GD value was found to be much higher within Yunnan
and Tibetan wheat than within Xinjiang wheat, but the GD value between Yunnan and Tibetan wheat was lower than those between
Yunnan and Xinjiang wheat, and between Tibetan and Xinjiang wheat. The cluster analysis indicated a closer relationship between
Yunnan and Tibetan wheat than that between Yunnan and Xinjiang wheat or between Tibetan and Xinjiang wheat.
Keywords: Yunnan wheat; Tibetan wheat; Xinjiang wheat; genetic diversity; SSR markers
The genetic diversity erosion of wheat has been
increasingly severe. The narrow genetic diversity
leads to vulnerability of biotic stresses, such as,
pathogens and insects, and abiotic stresses, such as
drought, salt, and so on. Genetic diversity is the ulti-
mate basis for genetic improvement. The knowledge
of genetic diversity of germplasms is critical for their
utilization in the improvement of crops. Therefore, it
is necessary to investigate the genetic diversity in
wheat germplasm, to broaden genetic variation in
wheat breeding.
The three unique wheat varieties, including Yun-
nan wheat (Triticum aestivum ssp. yunnanense King),
Tibetan wheat (Triticum aestivum ssp. tibetanum Shao),
and Xinjiang wheat (T. petropavloski Udats et
Migusch), were discovered in the Yunnan Province,
and the Tibetan, and Xinjiang autonomous regions of
China, respectively. These three types of unique wheat
624 Journal of Genetics and Genomics 遗传学报 Vol.34 No.7 2007
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are characterized by unique morphological characters,
such as, rachis fragility and glume tenacity. All these
unique wheat types also show particular traits useful
for wheat breeding, such as, resistance to preharvest
sprouting, tolerance to cold or heat, and so on. These
three unique hexaploid wheat types have a cytologi-
cally stable genome AABBDD. Morphological and
other cytological studies show that they are crossable
with common wheat[1−6]. Thus, these three unique
hexaploid wheat from western China are the primary
gene pool for common wheat and the interest genes of
these species can be readily introduced into common
wheat by genetic recombination[7−8]. This will cer-
tainly lead to the increase of genetic diversity in cul-
tivated wheat.
Allelic variation and genetic diversity at Glu-1,
Gli-1, and Gli-2 in Yunnan, Tibetan, and Xinjiang
wheat have been investigated in the previous study [9].
However, little is known about the genetic diversity
of these three unique wheat types, based on DNA se-
quences. In the present research, 52 accessions of the
three unique Chinese wheat types have been screened,
using 185 primers to assess their level of SSR-based
genetic diversity.
1 Materials and Methods
1.1 Plant materials
A total of 52 accessions, including 31 Yunnan
wheat, 15 Tibetan wheat, and 6 Xinjiang wheat col-
lected by the Cytogenetics Institute, Nanjing Agricul-
tural University, China, have been analyzed in this
study. Yunnan, Tibetan, and Xinjiang wheat were
kindly supplied by Shaoyun Wu (Institute of Crop
Germplasms, Yunnan Academy of Agricultural Sci-
ences) and Yuchen Dong (Chinese Academy of Agri-
cultural Sciences), respectively.
1.2 Genomic DNA extraction and PCR assay
DNA was extracted from the leaves of each of the
52 accessions grown in the field using an SDS
method[10]. Primer designation and chromosome loca-
tion of the amplified loci are presented in Table 1[11−13].
PCR amplifications were performed in a volume of 10
µL reaction mixtures, each containing 1 × PCR buffer
(10 mmol/L Tris-HCl pH 8.3, 50 mmol/L KCl ), 1
mmol/L MgCl2, 200 µmol/L dNTPs, 4 ng SSR primer,
1 U Taq polymerase, and 10 ng template DNA, using
the following PCR profile: initial denaturation in
94℃ for 3 min, 35 cycles at 94℃ for 50 s, X℃ (X℃
depending on the primer pair) for 1 min, 72℃ for 1
min, and a final extension at 72℃ for 10 min.
The amplification products were resolved on 8%
nondenaturing polyacrylamide gels followed by silver
staining. Electrophoresis was performed at 150 volt
constant power in 1 × TBE buffer as a running buffer,
and stopped depending on the expected product size
of each primer set.
1.3 Statistical analysis
Data were scored according to the presence or
absence of amplification products. If a band was pre-
sent in a genotype, it was designated 1; if no shared
band was present in another genotype, it was desig-
nated 0. The data matrix was then used to generate the
genetic similarity index (GS)[14]: GS = 2Nij/Ni + Nj, in
which Nij is the number of SSR bands in common
between genotypes i and j, and Ni and Nj are the total
number of SSR bands observed for genotypes i and j,
respectively. This value lies between 0 and 1, with a
score of 1 indicating that all fragments are common,
and 0 indicates no common fragments.
Proportion of polymorphic loci (P) and allelic
polymorphism information content (PIC) were used
to assess the genetic diversity. P = the number of po-
lymorphic loci/all of the number loci. PIC was calcu-
lated as described by Anderson et al. [15]: PIC =
1-Σ(Pi)2, where Pi is the proportion of the population
carrying the ith allele, calculated for each microsatel-
lite locus.
To assess the genetic diversity, cluster analysis
was performed based on genetic distance GD = 1−GS,
Haiyan Wang et al.: Assessment of Genetic Diversity of Yunnan, Tibetan, and Xinjiang Wheat Using SSR Markers 625
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with the DPS3.11 (Institute of Agricultural Entomol-
ogy, Zhejiang University) package using the un-
weighted pair-group method with arithmetical average
(UPGMA).
2 Results
In this study, 206 SSR primers were used for
PCR amplification of the total DNA of 52 genotypes,
among which 21 SSR primers gave no amplified pro-
duct in all accessions and they were discarded in the
following study (Table 1).
2.1 SSR polymorphisms in the Yunnan, Tibetan,
and Xinjiang wheat
2.1.1 SSR polymorphisms in the whole genome of
Yunnan, Tibetan, and Xinjiang wheat
Polymorphism and polymorphism information
Table 1 SSR primers and their chromosome location
Chromosome SSR primers Total
1A Xgwm497, Xgwm135, Xgwm136, Xgwm164, Xgdm33 5
1B Xgwm582, Xgwm153, Xgdm28, wmc44 4
1D Xgwm642, Xgwm337, Xgdm60, Xgdm111, wmc147 5
2A Xgwm636, Xgwm296, Xgwm356, Xgwm359, Xgwm372, Xgdm5, wmc261, wmc177 8
2B Xgwm526, Xgwm47, Xgwm388, Xgdm114, wmc243, wmc213, wmc265, wmc272, wmc175 9
2D Xgwm455, Xgwm484, Xgwm515, Xgwm539, Xgwm102, Xgwm210, Xgwm249, Xgwm301, Xgwm311, Xgwm55, Xgdm6, Xgdm35, Xgdm87, Xgdm107, Xgdm29, Xgdm77, Xgdm148, wmc167, wmc25 19
3A Xgwm674, Xgwm2, Xgwm30, Xgwm369, Xgwm480, wmc153, wmc169 7
3B Xgwm493, Xgwm533, Xgwm389, Xgwm131, Xgwm285, Xgdm120, Xgdm64, wmc326 8
3D Xgwm645, Xgwm3, Xgwm52, Xgwm71, Xgwm161, Xgwm183, Xgwm314, Xgwm341, Xgwm383, Xgdm38, Xgdm62, Xgdm128 12
4A Xgwm610, Xgwm637, Xgwm4, Xgdm145, wmc219, wmc232, wmc173 7
4B Xgwm538, Xgwm251, wmc238, wmc47 4
4D Xgwm608, Xgwm165, Xgdm125, Xgdm129, Xgdm34, Xgdm40, wmc331, wmc52 8
5A Xgwm129, Xgwm154, Xgwm304, wmc215, wmc327, wmc96 6
5B Xgwm443, Xgwm540, Xgwm544, Xgwm554, Xgwm604, Xgwm335, Xgwm408, Xgdm133, Xgdm149, Xgdm146, wmc27, wmc149, wmc262 13
5D Xgwm583, Xgwm639, Xgwm654, Xgwm182, Xgwm192, Xgwm269, Xgwm358, Xgdm43, Xgdm63, Xgdm68, Xgdm116, Xgdm138, Xgdm115, Xgdm136, wmc97, wmc161, wmc233 17
6A Xgwm427, Xgwm494, Xgwm570, Xgwm617, Xgwm169 5
6B Xgwm508, Xgwm613, Xgwm626, Xgwm191, wmc182, wmc95, wmc104 7
6D Xgwm469, Xgdm14, Xgdm36, Xgdm98, Xgdm127, Xgdm132, Xgdm141 7
7A Xgwm471, Xgwm666, Xgwm60, Xgwm130, Xgwm260, Xgwm276, Xgwm282, Xgwm332, Xgdm152, wmc273, wmc168 11
7B Xgwm573, Xgwm577, Xgwm611, Xgwm644, Xgwm16, Xgwm43, Xgwm68, Xgwm146, Xgwm274, Xgwm297, wmc216 11
7D Xgwm428, Xgwm37, Xgwm295, Xgwm350, Xgdm46, Xgdm67, Xgdm86, Xgdm130, Xgdm150, Xgdm142, wmc94, wmc157 12
626 Journal of Genetics and Genomics 遗传学报 Vol.34 No.7 2007
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content detected by 185 SSR primers in Yunnan, Ti-
betan, and Xinjiang wheat are shown in Tables 2 and
3. In Yunnan wheat, 135 of the 185 SSR markers (P =
72.97%) were found to be polymorphic, and the oth-
ers revealed no polymorphism. For the 185 SSR
markers analyzed, a total of 488 alleles were detected.
The number of alleles per SSR primer ranged from
one to nine. On an average, 2.64 alleles were detected
per locus. The maximum number of alleles was ob-
served at wmc161 (chromosome 5D). The values of
PIC were also estimated, and the highest value of
0.7852 was recorded for Xgdm63 (chromosome 5D).
Table 2 Polymorphisms detected by 185 SSR primers in Yunnan, Tibetan, and Xinjiang wheat
Number of amplified alleles
Number of amplified alleles/primers
Chromosome Number of SSR primers Yunnan Tibetan Xinjiang Yunnan Tibetan Xinjiang
1A 5 14 14 8 2.80 2.80 1.60
1B 4 11 8 7 2.75 2.00 1.75
1D 5 10 9 8 2.00 1.80 1.60
Homoeologous group 1 14 35 31 23 2.5 2.21 1.64
2A 8 23 26 17 2.88 3.25 2.13
2B 9 26 25 13 2.89 2.78 1.44
2D 19 47 44 30 2.47 2.32 1.58
Homoeologous group 2 36 96 95 60 2.67 2.64 1.67
3A 7 27 21 10 3.86 3.00 1.43
3B 8 25 28 16 3.13 3.50 2.00
3D 12 25 24 20 2.08 2.00 1.67
Homoeologous group 3 27 77 73 46 2.85 2.70 1.70
4A 7 18 17 14 2.57 2.43 2.00
4B 4 14 12 8 3.50 3.00 2.00
4D 8 18 15 13 2.25 1.88 1.63
Homoeologous group 4 19 50 44 35 2.63 2.32 1.84
5A 6 16 16 7 2.67 2.67 1.17
5B 13 38 38 22 2.92 2.92 1.69
5D 17 41 41 27 2.41 2.41 1.59
Homoeologous group 5 36 95 95 56 2.64 2.64 1.56
6A 5 10 11 5 2.00 2.20 1.00
6B 7 15 16 14 2.14 2.29 2.00
6D 7 19 16 11 2.71 2.29 1.57
Homoeologous group 6 19 44 43 30 2.32 2.26 1.58
7A 11 27 30 19 2.45 2.73 1.73
7B 11 31 30 19 2.82 2.73 1.73
7D 12 34 31 20 2.83 2.58 1.67
Homoeologous group 7 34 92 92 58 2.71 2.71 1.71
A genome 49 135 135 80 2.76 2.76 1.63
B genome 56 160 157 99 2.86 2.80 1.77
D genome 80 194 180 129 2.43 2.25 1.61
Total 185 488 472 308 2.64 2.55 1.66
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Table 3 Polymorphism information content of 185 SSR primers in Yunnan, Tibetan, and Xinjiang wheat
Polymorphism information content (PIC)
Chromosome
Yunnan wheat Tibetan wheat Xinjiang wheat Total
1A 0.2543 0.3004 0.1667 0.3358
1B 0.3241 0.3689 0.2500 0.4360
1D 0.0720 0.1173 0.1556 0.0986
Homoeologous group 1 0.2093 0.2546 0.1865 0.2797
2A 0.2810 0.4083 0.3333 0.3616
2B 0.2705 0.3802 0.1604 0.3869
2D 0.2534 0.3039 0.1696 0.3358
Homoeologous group 2 0.2637 0.3451 0.2037 0.3543
3A 0.4076 0.4190 0.1270 0.4612
3B 0.4105 0.4444 0.3541 0.4786
3D 0.1859 0.2111 0.1574 0.2325
Homoeologous group 3 0.3099 0.3342 0.2078 0.3633
4A 0.3479 0.2425 0.3730 0.4055
4B 0.3783 0.3556 0.2500 0.4411
4D 0.3130 0.2222 0.2570 0.3072
Homoeologous group 4 0.3396 0.2577 0.2982 0.3716
5A 0.3146 0.2726 0.0463 0.3302
5B 0.3264 0.3856 0.2818 0.3804
5D 0.1691 0.2379 0.1667 0.2302
Homoeologous group 5 0.2501 0.2970 0.1882 0.3011
6A 0.0837 0.1778 0.0000 0.1469
6B 0.3624 0.3911 0.2937 0.4097
6D 0.3544 0.3429 0.1746 0.4022
Homoeologous group 6 0.2861 0.3171 0.1725 0.3377
7A 0.2512 0.2723 0.1919 0.3109
7B 0.2348 0.3362 0.2071 0.3458
7D 0.3418 0.3082 0.1898 0.2713
Homoeologous group 7 0.2779 0.3056 0.1960 0.3082
A genome 0.2832 0.3037 0.1916 0.3423
B genome 0.3195 0.3808 0.2544 0.4000
D genome 0.2421 0.2602 0.1785 0.2763
The lowest and highest PIC values were underlined, which observed in 1D chromosome and B genome, respectively.
In Tibetan wheat, a total of 472 alleles were de-
tected with 185 SSR markers. The number of alleles
amplified by each SSR primer pair ranged from one
to eight, with an average of 2.55. The maximum
number of alleles was observed at wmc161 (chromo-
some 5D) and Xgwm130 (chromosome 7A).
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In Xinjiang wheat, the total number of alleles
detected was 308, ranging from one to five per locus
with a mean value of 1.66 alleles per locus. The larg-
est number of alleles per locus occurred at Xgdm62
(chromosome 3D).
2.1.2 SSR polymorphisms in all the 21 chromo-
somes of Yunnan, Tibetan, and Xinjiang wheat
Substantial differences in polymorphisms de-
tected by SSR were found in all the 21 chromosomes
in Yunnan, Tibetan, and Xinjiang wheat.
In Yunnan wheat, the higher number of alleles per
locus was detected in 3A, 4B, and 3B, with an average
of 3.86, 3.50, and 3.13 alleles per locus, respectively.
1D and 6A had a relatively lower number of alleles per
locus. Average allele per microsatellite locus of 1D and
6A was 2.0 and 2.0, respectively. The PIC value was
also estimated, as shown in Table 3, and the highest
and lowest values of 0.4105 and 0.0720 were recorded
for chromosomes 3B and 1D, respectively.
In Tibetan wheat, the highest number of alleles
per locus and value of PIC in 3B were estimated to be
3.50 and 0.4444, respectively. The lowest number of
alleles per locus and PIC values were observed in 1D,
and were 1.80 and 0.1173, respectively.
In Xinjiang wheat, the highest and lowest num-
ber of alleles per locus was detected in 2A and 6A
with 2.13 and 1.80, respectively. The highest and
lowest PIC values were observed in 4A and 6A with
0.3730 and 0.0000, respectively.
2.1.3 SSR polymorphisms in different homoeologous
groups of Yunnan, Tibetan, and Xinjiang wheat
Significant differences of polymorphisms de-
tected by SSR were observed in different homoeolo-
gous groups of Yunnan, Tibetan, and Xinjiang wheat.
In Yunnan wheat, the highest and lowest number
of alleles per locus was detected in homoeologous
groups 3 and 6, respectively. A total of 77 alleles were
detected, with an average allele number of 2.85 per
locus, in homoeologous group 3. A total of 44 alleles
were detected with an average allele number of 2.32
per locus in homoeologous group 6. The highest and
lowest PIC values were detected in homoeologous
groups 1 and 4, 0.2093 and 0.3369, respectively.
In Tibetan wheat, the relatively higher number of
alleles per locus was detected in homoeologous groups
7 and 3 with an average of 2.71 and 2.70 alleles per
locus, respectively. The homoeologous groups 6 and 1
had significant lower number of alleles per locus. The
average number of alleles per microsatellite locus in
homoeologous groups 6 and 1 were 2.26 and 2.20, re-
spectively. The highest and lowest PIC values were
detected in the homoeologous groups 2 and 1, which
were 0.3451 and 0.2546, respectively.
In Xinjiang wheat, the higher number of alleles
per locus was detected in homoeologous groups 4, 7,
and 3 with an average of 1.84, 1.71, and 1.70 alleles
per locus, respectively. The lower number of alleles
per locus was detected in homoeologous groups 6 and
5 with an average of 1.58 and 1.56 alleles per locus,
respectively. The highest and lowest PIC values were
detected in homoeologous groups 4 and 6, which
were 0.2982 and 0.1725, respectively.
2.1.4 SSR polymorphisms in the three genomes of
Yunnan, Tibetan, and Xinjiang wheat
There were substantial differences in polymor-
phisms detected by SSR in the three genomes of
Yunnan, Tibetan, and Xinjiang wheat (Table 2). In the
three unique wheat types, both the highest number of
alleles per locus and the highest PIC value were de-
tected in the B genome, and both the lowest number
of alleles per locus and the lowest PIC value were
detected in the D genome.
2.2 Genetic differentiation among and within
Yunnan, Tibetan, and Xinjiang wheat
To understand the genetic variation within Yun-
nan, Tibetan, and Xinjiang wheat, genetic distance
based on SSR data between all possible pairs of ac-
cessions was calculated (Table 4). The mean GD
value was 0.1801, ranging from 0.1000−0.2737
within Yunnan wheat. The GD value was smallest
between YN8 and YN7, the greatest GD value was
found between YN23 and YN7. The GD value was
smallest between TB13 and TB18 (0.1505), greatest
between TB5 and TB22 (0.2669), and averaged
0.2073 within Tibetan wheat. The smallest GD value
Haiyan Wang et al.: Assessment of Genetic Diversity of Yunnan, Tibetan, and Xinjiang Wheat Using SSR Markers 629
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within Xinjiang wheat was 0.0698 between XJ4 and
XJ5, and the greatest GD value was between XJ1 and
XJ6 (0.2454), with an average GD value of 0.1675.
The average GD value was 0.2222, ranging from
0.1565 to 0.3047, between Yunnan and Tibetan wheat.
The highest GD value was found between YN16 and
TB3, and the smallest GD value was between YN21
and TB15.
The mean GD value was 0.3051, ranging from
0.2171 to 0.4336, between Yunnan and Xinjiang
wheat. The highest GD value between YN2 and XJ1
and the smallest GD value between YN3 and XJ4
were observed.
The GD value varied from 0.2210 to 0.3869,
with the mean of 0.2912 between Tibetan and Xinji-
ang wheat. The highest GD value was identified be-
tween TB18 and XJ1, whereas, the lowest GD value
was identified between TB22 and XJ4.
From Table 4, it is found that the average GD
value within Yunnan and Tibetan wheat are higher
than that within Xinjiang wheat. This suggests that
there should be a much higher genetic diversity within
Yunnan and Tibetan wheat than within Xinjiang
wheat. It can also be seen that the average GD value
between Yunnan and Tibetan wheat is lower than
those between Xinjiang and Yunnan wheat, and Ti-
betan wheat. These indicate that there might be a
much closer relationship between Yunnan and Tibetan
wheat than that between Xinjiang and Yunnan wheat,
and Tibetan wheat.
2.3 Cluster analysis of the genetic relationships
among Yunnan, Tibetan, and Xinjiang wheat
To study the genetic relationships of Yunnan,
Tibetan, and Xinjiang wheat, the matrix of GD was
used for cluster analysis, by using the UPGMA
method (Fig. 1). A dendrogram was constructed,
which divided all accessions into two major groups, I
and II, group I containing all accessions of the Xinji-
ang wheat, and group II containing all accessions of
Yunnan and Tibetan wheat. Group II could be further
separated into two subclusters, Ia and IIb, subcluster
Ia containing all accessions of Yunnan wheat and one
accession of Tibetan wheat and subcluster II b con-
taining other 14 accessions of Tibetan wheat. This
suggested that Yunnan and Tibetan wheat had a closer
relationship, but their relationship with Xinjiang
wheat was distant.
3 Discussion
Wei et al.[16,17] investigated 32 accessions of
unique wheat of western China using APAGE,
SDS-PAGE, STS-PCR, and SSR markers and found
that Tibetan wheat and Xinjiang wheat had higher
genetic diversity than Yunnan wheat. Ward et al.[18]
compared the genetic diversity of three unique wheat
Table 4 Genetic distance coefficient detected by SSR primers in Yunnan, Tibetan, and Xinjiang wheat
Accessions Yunnan wheat Tibetan wheat Xinjiang wheat
Yunnan wheat Mean 0.1801 0.2222 0.3051
Min 0.1000(YN8 and YN7) 0.1565(YN21 and TB15) 0.2171(YN3 and XJ4)
Max 0.2737(YN23 and YN7) 0.3047(YN16 and TB3) 0.4336(YN2 and XJ1)
Tibetan wheat Mean 0.2222 0.2073 0.2912
Min 0.1565(YN21 and TB15) 0.1505(TB13 and TB18) 0.2210( TB22 and XJ4)
Max 0.3047(YN16 and TB3) 0.2669(TB5 and TB22) 0.3869(TB18 and XJ1)
Xinjiang wheat Mean 0.3051 0.2912 0.1675
Min 0.2171 (YN3 and XJ4) 0.2210 ( TB22 and XJ4) 0.0698(XJ4 and XJ5)
Max 0.4336(YN2 and XJ1) 0.3869(TB18 and XJ1) 0.2454(XJ1 and XJ6)
YN: Yunnan wheat; TB: Tibetan wheat; XJ: Xinjiang wheat.
630 Journal of Genetics and Genomics 遗传学报 Vol.34 No.7 2007
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Fig. 1 Dendrogram based on genetic distance from 185 SSR in the whole genome of 51 accessions of Yunnan(YN), Ti-
betan(TB), and Xinjiang(XJ) wheat and Chinese spring(CS)
Haiyan Wang et al.: Assessment of Genetic Diversity of Yunnan, Tibetan, and Xinjiang Wheat Using SSR Markers 631
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types of western China based on RFLP analysis and
found that Tibetan wheat had the highest genetic di-
versity and Yunnan wheat had the lowest genetic di-
versity. Cui and Ma [18] analyzed the esterase isozyme
of dry seeds, anthers, and immature seeds from 54
accessions of indigeous Chinese wheat and found that
Yunnan and Tibetan wheat had a higher genetic diver-
sity. In the present study, SSR markers were used to
estimate the extent of genetic diversity of Yunnan,
Tibetan, and Xinjiang wheat. The results indicated
that Yunnan and Tibetan wheat had a higher genetic
diversity than Xinjiang wheat. This result was consis-
tent with the results obtained from Gli-1, Gli-2,
Glu-1[9], and esterase isozyme[19], but it was divergent
from the results obtained from Gli-1, Gli-2,
Glu-1[16,17], and RFLP analysis[18]. Different reports
concerning genetic diversity of Yunnan, Tibetan, and
Xinjiang wheat might be influenced by inadequate
and different accession collection and different types
of molecular markers used in each study.
Yunnan and Tibetan wheat had primitive traits
such as iron glume and brittle rachis, and they were
classified as being of a similar type, based on the
spike trait. The Tibetan wheat was distributed in the
Yaluzangbu River valley and the upper reaches of the
Lancang and Nu Rivers of Tibet. The Yunnan wheat
was also distributed in the reaches of the Lancang
River of Yunnan. From this assessment of the genetic
diversity of Yunnan, Tibetan, and Xinjiang wheat
types, using SSR markers, the mean GD value be-
tween Yunnan and Tibetan wheat was lower than
those between Xinjiang and Yunnan wheat, and Ti-
betan wheat. The cluster analysis further showed that
the relationship between Yunnan and Tibetan wheat
was closer than that between Xinjiang and Yunnan
wheat, and Tibetan wheat. According to these results,
it is presumed that Yunnan and Tibetan wheat have a
closer relationship and they might have the same ori-
gin.
Among the three genomes, it was found that the
number of alleles per locus and PIC value was as B >
A > D in the three unique wheat types, indicating that
the B genome showed the highest, A genome the in-
termediate, and D genome always the lowest genetic
diversity, especially in chromosome 1D of these three
unique wheat types. The results mentioned above
were in good agreement with the results obtained by
karyotype, Gli-1, Gli-2, Glu-1, RFLP, and SSR analy-
sis[1, 2, 5, 9, 16−18, 20−22]. The different contribution of
three genomes to genetic variation within these three
unique wheat types was confirmed in this study.
This is consistent with the distribution of microsa-
tellite markers and RFLP markers in the three ge-
nomes of common wheat analyzed by Ni et al.[23]
and Jia et al [22].
Why did the B genome have the highest genetic
diversity and D genome have the lowest genetic di-
versity in these three unique wheat types? Several
hypotheses were proposed, and the most plausible
explanation relates to the evolutionary history of
each of the hexaploid wheat genome. The B genome
was derived from a species or several species closely
related to the A. speltoides, a cross-pollinating spe-
cies. Both A and D genomes traced their origins to
self-pollinating diploids T. urartu Thum. ex Gand.
and Ae. tauschii Coss., respectively. Generally, a
cross-pollinating species had more genetic diversity
than the self-pollinating species. Therefore, the ge-
netic diversity of the B genome might be higher than
those of A and D genomes in the primitive hexaploid
wheat. The second reason was the number and distri-
bution of genome in the hexaploid wheat. During the
evolution of the hexaploid wheat, A and B genomes
produced more tetraploid wheat, such as T. dicoc-
coides, T. dicoccum, T. turgidum, T. durum, T. turani-
cum, T. polonicum, and T. carthlicum. All these
tetraploid wheat could cross with hexaploid wheat,
and the result could enrich the genetic diversity of A
and B genome species. But the D genome species did
not produce any tetraploid wheat with A and B ge-
nome. Therefore, the gene exchange of D genome
was reduced and the genetic diversity of D genome
632 Journal of Genetics and Genomics 遗传学报 Vol.34 No.7 2007
www.jgenetgenomics.org
was restricted. During the evolution of the hexaploid
wheat, tetraploid wheat was initially produced, and
then the tetraploid wheat crossed with Aegilops
tauschii, and produced the hexaploid wheat. Conse-
quently, the opportunity of the gene exchange of D
genome with A or B genome was lower than that be-
tween B and A genome. The third reason was the re-
petitive DNA sequences and the length of the genome
in these three kinds of unique wheat. C-banding indi-
cated that the B genome chromosomes were the most
heavily labeled in each of the A, B, and D genomes
and the B genome chromosomes enriched the highly
repetitive DNA sequences. Also the length of the B
genome chromosomes was longer than the length of
the A and D genomes. The age of the lineage of the
diploid donors at the time of the polyploidization
events might be another contributing factor. Addition-
ally, the contributing factor was the unique geography
and climate of Yunnan, Tibet, and Xinjiang resulting
in their special selection.
Yunnan, Tibetan, and Xinjiang wheat are three
unique wheat types of western China, and they show a
peculiar usefulness for wheat breeding, such as resis-
tance to preharvest sprouting, cold tolerance or heat
tolerance, and they are very important germplasms for
the research of the evolution and taxonomy of wheat.
On account of the research condition, the accessions
of Yunnan, Tibetan, and Xinjiang wheat used in this
study are relatively few.
Only the genetic diversity of these three unique
wheat types was assessed, based on Gli-1, Gli-2,
Glu-1, and SSR markers. To fully evaluate the genetic
diversity and further utilize the three kinds of unique
wheat, more germplasms should be collected and
more characters and more analytical methods should
be studied.
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利用 SSR标记分析云南、西藏和新疆小麦的遗传多样性
王海燕, 王秀娥, 陈佩度, 刘大钧
南京农业大学作物遗传与种质创新国家重点实验室, 南京农业大学细胞遗传研究所, 南京 210095
摘 要: 用 185 对 SSR 引物对 52 份中国西部特有小麦的遗传多样性进行了研究分析。在 31 份云南小麦材料中, 共检测到
488个等位变异, 每一个 SSR引物可检测到 1至 9个等位变异, 平均为 2.64个; 平均 PIC值为 0.2764。在 15份西藏小麦材
料中, 共检测到 472个等位变异, 每个引物可扩增出 1到 8个等位变异, 平均为 2.55个; 平均 PIC值为 0.3082。在 6份新疆
小麦材料中, 共检测到 308个等位变异, 每一个 SSR引物可检测 1到 5个等位变异, 平均为 1.66个; 平均 PIC值为 0.1944。
185对 SSR引物在云南、西藏和新疆小麦的 21条染色体、7个部分同源群和 3个染色体组上检测到的等位位点的多态性存
在明显差异。云南、西藏和新疆小麦均以 3B 染色体较高, 而 1D 染色体最低; 在 7 个部分同源群中, 均以第三部分同源群
最高, 第六部分同源群最低; 在 A、B和 D染色体组上, 均以 B染色体组最高, D染色体组最低, A染色体组居中。利用 185
对 SSR引物计算了云南、西藏和新疆小麦群体内及其群体间的遗传距离(GD)和平均遗传距离, 结果显示, 西藏小麦和云南
小麦群体内的平均遗传距离要高于新疆小麦, 而云南小麦和西藏小麦间的平均遗传距离低于两者与新疆小麦的平均遗传距
离。聚类分析结果也表明, 云南小麦和西藏小麦的亲缘关系较近, 但两者与新疆小麦的亲缘关系相对较远。
关键词: 云南小麦；西藏小麦；新疆小麦；遗传多样性；SSR
作者简介: 王海燕(1975−)，女，博士研究生，研究方向：小麦细胞分子遗传学