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1.  Population structure of the wild soybean (Glycine soja) in China: implications from microsatellite analyses 
Annals of Botany  2012;110(4):777-785.
Background and Aims
Wild soybean (Glycine soja), a native species of East Asia, is the closest wild relative of the cultivated soybean (G. max) and supplies valuable genetic resources for cultivar breeding. Analyses of the genetic variation and population structure of wild soybean are fundamental for effective conservation studies and utilization of this valuable genetic resource.
In this study, 40 wild soybean populations from China were genotyped with 20 microsatellites to investigate the natural population structure and genetic diversity. These results were integrated with previous microsatellite analyses for 231 representative individuals from East Asia to investigate the genetic relationships of wild soybeans from China.
Key Results
Analysis of molecular variance (AMOVA) revealed that 43·92 % of the molecular variance occurred within populations, although relatively low genetic diversity was detected for natural wild soybean populations. Most of the populations exhibited significant effects of a genetic bottleneck. Principal co-ordinate analysis, construction of a Neighbor–Joining tree and Bayesian clustering indicated two main genotypic clusters of wild soybean from China. The wild soybean populations, which are distributed in north-east and south China, separated by the Huang-Huai Valley, displayed similar genotypes, whereas those populations from the Huang-Huai Valley were different.
The previously unknown population structure of the natural populations of wild soybean distributed throughout China was determined. Two evolutionarily significant units were defined and further analysed by combining genetic diversity and structure analyses from Chinese populations with representative samples from Eastern Asia. The study suggests that during the glacial period there may have been an expansion route between south-east and north-east China, via the temperate forests in the East China Sea Land Bridge, which resulted in similar genotypes of wild soybean populations from these regions. Genetic diversity and bottleneck analysis supports that both extensive collection of germplasm resources and habitat management strategies should be undertaken for effective conservation studies of these important wild soybean resources.
PMCID: PMC3423801  PMID: 22791743
Wild soybean; Glycine soja; microsatellites; genetic diversity; population structure
2.  A single origin and moderate bottleneck during domestication of soybean (Glycine max): implications from microsatellites and nucleotide sequences 
Annals of Botany  2010;106(3):505-514.
Background and Aims
It is essential to illuminate the evolutionary history of crop domestication in order to understand further the origin and development of modern cultivation and agronomy; however, despite being one of the most important crops, the domestication origin and bottleneck of soybean (Glycine max) are poorly understood. In the present study, microsatellites and nucleotide sequences were employed to elucidate the domestication genetics of soybean.
The genomes of 79 landrace soybeans (endemic cultivated soybeans) and 231 wild soybeans (G. soja) that represented the species-wide distribution of wild soybean in East Asia were scanned with 56 microsatellites to identify the genetic structure and domestication origin of soybean. To understand better the domestication bottleneck, four nucleotide sequences were selected to simulate the domestication bottleneck.
Key Results
Model-based analysis revealed that most of the landrace genotypes were assigned to the inferred wild soybean cluster of south China, South Korea and Japan. Phylogeny for wild and landrace soybeans showed that all landrace soybeans formed a single cluster supporting a monophyletic origin of all the cultivars. The populations of the nearest branches which were basal to the cultivar lineage were wild soybeans from south China. The coalescent simulation detected a bottleneck severity of K′ = 2 during soybean domestication, which could be explained by a foundation population of 6000 individuals if domestication duration lasted 3000 years.
As a result of integrating geographic distribution with microsatellite genotype assignment and phylogeny between landrace and wild soybeans, a single origin of soybean in south China is proposed. The coalescent simulation revealed a moderate genetic bottleneck with an effective wild soybean population used for domestication estimated to be ≈2 % of the total number of ancestral wild soybeans. Wild soybeans in Asia, especially in south China contain tremendous genetic resources for cultivar improvement.
PMCID: PMC2924825  PMID: 20566681
Wild soybean; Glycine soja; cultivated soybean; G. max; microsatellite; nucleotide sequence; domestication origin; domestication bottleneck
3.  Ancient genome duplications during the evolution of kiwifruit (Actinidia) and related Ericales 
Annals of Botany  2010;106(3):497-504.
Background and Aims
To assess the number and phylogenetic distribution of large-scale genome duplications in the ancestry of Actinidia, publicly available expressed sequenced tags (ESTs) for members of the Actinidiaceae and related Ericales, including tea (Camellia sinensis), were analysed.
Synonymous divergences (Ks) were calculated for all duplications within gene families and examined for evidence of large-scale duplication events. Phylogenetic comparisons for a selection of orthologues among several related species in Ericales and two outgroups permitted placement of duplication events in relation to lineage divergences. Gene ontology (GO) categories were analysed for each whole-genome duplication (WGD) and the whole transcriptome.
Key Results
Evidence for three ancient WGDs in Actinidia was found. Analyses of paleologue GO categories indicated a different pattern of retained genes for each genome duplication, but a pattern consistent with the dosage-balance hypothesis among all retained paleologues.
This study provides evidence for one independent WGD in the ancestry of Actinidia (Ad-α), a WGD shared by Actinidia and Camellia (Ad-β), and the well-established At-γ WGD that occurred prior to the divergence of all taxa examined. More ESTs in other taxa are needed to elucidate which groups in Ericales share the Ad-β or Ad-α duplications and their impact on diversification.
PMCID: PMC2924827  PMID: 20576738
Paleopolyploidy; Actinidiaceae; Ericales; Actinidia; Camellia; kiwi; genome duplication; dosage balance
4.  Phylogeny of Sinojackia (Styracaceae) Based on DNA Sequence and Microsatellite Data: Implications for Taxonomy and Conservation 
Annals of Botany  2008;101(5):651-659.
Background and Aims
The genus Sinojackia consists of eight species, all endemic to China. All species of Sinojackia are endangered or threatened owing to poor recruitment within populations. Information on molecular phylogenetics is critical for developing successful conservation strategies for this genus.
Combined DNA sequence data from the nuclear ribosomal internal transcribed spacer regions and plastid psbA–trnH intergenic spacer and microsatellite data were used to infer a phylogeny of the genus.
Key Results
Parsimony analysis of the combined sequence data and multivariate analysis based on fruit characters indicated that Sinojackia dolichocarpa is monophyletic and genetically well separated from the other Sinojackia species, thus supporting its rank at the generic level as Changiostyrax. Phylogenetic relationships within Sinojackia sensu stricto are unresolved from the combined sequence data. A UPGMA dendrogram based on seven microsatellite loci of 96 individual plants yielded a first-diverging cluster of all individuals of S. microcarpa. The remaining species form another cluster without any definitive patterns corresponding to current species circumscriptions, suggesting either extensive hybridization or incipient speciation.
The results suggest that there are too many species recognized within Sinojackia sensu stricto, but this must be further assessed with comprehensive morphological and taxonomic revisionary work. The implications of the phylogenetic data for conservation are discussed.
PMCID: PMC2710174  PMID: 18245106
Changiostyrax; conservation; phylogeny; Sinojackia; Styracaceae

Results 1-4 (4)