Genetic diversity of Chinese common bean (Phaseolus vulgaris L.)
assessed with simple sequence repeat (SSR) markers
Xiaoyan Zhang1, Matthew W. Blair2, Shumin Wang1,3
1ICS, CAAS- Institute of Crop Science, Chinese Academy of Agricultural Sciences, 100081, Beijing China
2CIAT- International Center for Tropical Agriculture, AA6713, Cali, Colombia
3NFCRI- The National Key Facility for Crop Gene Resources and Genetic Improvement, 100081, Beijing China
Introduction Figures and Tables Results
China is a major producer of common beans (fifth A total of 166 alleles were detected with an average
worldwide in dry beans and first in snap beans) with of 5.5 alleles per locus for all microsatellites.
DIM3
production distributed in many agricultural areas of the (5.6%)
The landraces were clustered into Andean and
country, including primary bean growing areas in the Mesoamerican groups bu principal component
provinces of Guizhou, Heilongjiang, Neimenggu, analysis (Figure 1).
Sichuan and Yunnan (Wang et al.1999). A total of
G19833
Meso 1
The level of diversity for Chinese landraces of
1,204,000 hectares of dry beans and 213,000 hectares Meso 2
Andean origin was higher than for the Chinese
of snap beans are grown in China (FAO, 2006). The DOR364 landraces of Mesoamerican origin (Table 1) due to the
crop is thought to have a history of over four hundred
presence of more infrequent alleles in this first group.
years in China and was suspected of having been
introduced directly from Latin America. Common beans Two subgroups were identified in each genepool
in China are mainly produced under rain-fed conditions
DIM2
(6.7%) DIM1
(43.6%)
group (Figure 2) with one of the Mesoamerican
Andean
in traditional farming systems that often include rotation Mesoamerican
subgroups arising from introgression between the
with vegetables or intercropping with maize. Some Figure 1. Multiple correspondence analysis for 229 common bean genotypes
genepools and the two Andean subgroups
commercial classes have become an important export based on 30 microsatellite markers showing accessions falling the Andean representing races Nueva Granada and Peru.
(circles) or Mesoamerican (banners) groups. Positions of control genotypes
crop and are favorites of international trade reaching indicated by arrows and names. Gene flow (Nm) was 0.86 or below between
799,690 tons exported (FAO, 2006) making China one subgroups from different gene pools and 2.6 or above
of the largest exporters of the crop. Evaluation of the between subgroups within the genepools (Table 2).
A B
genetic diversity present in Chinese accessions of Genetic differentiation and genetic distance between
Andean 1
common beans is essential for conservation, Andean and Mesoamerican group were 0.331 and
management and utilization of these genetic resources. Andean 2 1.1123 respectively.
The objective of this research therefore was was to Polymorphism level between landraces within the
evaluate a collection of Chinese landraces with Mesoamerican group was lower than between
microsatellite markers to evaluate the genetic variability, accessions within the Andean group (Nei’s indices of
genepool identity and relationships within and between G19280AMW
0.367 and 0.423, respectively) even though the
Meso 1
the groups identified among the genotypes. sample evaluated contained more of the former
genepool than the latter genepool.
Materials and Methods
Genotypes: A total of 229 common bean genotypes Discussion
Meso 2
from China were used in this study, of which 131 were
0.00
0.20
0.40
0.60
0.80
1.00
0.00 1.08 2.16
supplied by the Genetic Resource Unit of CIAT and 98 Q value Euclidean distance Chinese common bean accessions could be
were provided by the National Gene Bank of CAAS. In Figure 2. UPGMA dendrogram and Structure analysis (with K=4) for 229 Chinese classified into the two gene pools of common bean
common bean genotypes showing Andean and Mesoamerican subgroups as
addition to these accessions, two check cultivars were described in the text. based on microsatellites analysis.
included for comparisons: G19833 representing the Co-existence of Andean and Mesoamerican
Andean gene pool; and DOR364 representing the Table 1. Genetic diversity for Chinese common bean accessions classified by
genotypes has been observed both in regions within
subgroups within the Andean and Mesoamerican gene pools.
Mesoamerica gene pool (Blair et al. 2006). Accessions the Western hemisphere that were outside of the
from CIAT were mostly from the northeast and Groups na ne H0 Nei's P % centers of origin such as Brazil and the Caribbean and
southeast of China complementing genotypes supplied Andean 1 2.5667 1.7875 0.0333 0.3043 22 73.33
in other parts of the world to which common beans
Andean 2 3.7333 2.2797 0.0273 0.4420 30 100.00
by CAAS which were mostly from the northwest and Andean total 3.9667 2.2963 0.0294 0.4233 30 100.00 were transported to such as Europe and Africa.
southwest. Since the accessions obtained from both Meso 1 5.0000 1.9674 0.0500 0.3434 30 100.00
Meso 2 3.1333 2.1174 0.2533 0.4455 29 96.67
Chinese accessions from the Mesoamerican group
gene banks were not segregating for seed color we
Meso total 5.3000 2.0465 0.0682 0.3665 30 100.00 were likely to be from race Mesoamerica given their
decided to evaluate a bulk of tissue from four plants per Overall total 6.0667 2.6420 0.0581 0.5351 30 100.00 close association with the control genotype DOR364,
accession for DNA polymorphisms. which is from this race. It seems less likely that races
Microsatellite Analysis: Thirty microsatellite markers Durango or Jalisco arrived in China since overall
Table 2. Genetic differentiation (GST), gene flow (Nm), genetic distance (GD) and
were selected according to polymorphism and stability genetic identity (I) among and between subgroups of Chinese accessions
diversity within the Mesoamerican genepool was poor
of amplification as per Blair et al. (2006). Microsatellite analyzed with microsatellite markers. and diversity that was present was due to
alleles were evaluated on silver stained 4% Groups GST I
introgression between the genepools.
polyacrylamide (29:1 acrylamide:bis-acrylamide) gels. Andean Andean Meso Meso Andean Andean Meso Meso
Therefore we can hypothesize that only one race
1 2 1 2 1 2 1 2
Data Analysis: Allele sizes were scored for all
Andean 1 **** 0.08 0.41 0.29 **** 0.9039 0.2387 0.5179 contributed to Mesoamerican bean diversity in China,
Andean 2 2.87 **** 0.32 0.23 0.1010 **** 0.3346 0.5218
genotypes on the basis of comparison to a 10-bp Meso 1 0.37 0.53 **** 0.09 1.4327 1.0948 **** 0.8589 explaining why diversity in this genepool is so much
Meso 2 0.62 0.86 2.61 **** 0.6580 0.6505 0.1521 ****
molecular-weight ladder and an allele matrix was Nm GD lower than in the corresponding Andean gene pool
prepared from this dataset. Multiple correspondence accessions. In contrast, the Chinese accessions in the
Andean group probably represented both race Nueva
analysis was performed with NTSYS and Euclidean References / Acknowledgements Granada and race Peru germplasm.
distance between genotypes for UPGMA clustering. 1. Blair MW, Giraldo MC, Buendia HF, Tovar E, Duque MC, Beebe SE (2006)
Principal component analysis was carried out with SAS. Microsatellite marker diversity in common bean (Phaseolus vulgaris L.) Theor In conclusion, our results suggest that China is an
Genetic variation within and among the groups and Appl Genet 113: 100–109. important secondary center of diversity for common
2. FAO (2006) http://faostat.fao.org/
subgroups detected was analyzed with POPGENE 3. Wang SM, Zhang YZ, Wang BS, Liu SW, Li JY (1996) Evaluation of common bean equivalent to other ‘Old World’ secondary
software and the relationship between populations (K) bean germplasm. Crop Genet Resour 3:12–14 centers of diversity and that the diverse landraces can
4. This poster is based on a publication in Theor Appl Genetics (2008).
was evaluated with the software STRUCTURE. 5. We acknowledge the Generation Challenge Program for funding. be the basis for crop improvement.