Asian Gene Pool Research Articles

Morphological and chemical identification of Ephedra sinica at Xiaohe Cemetery in Lop Nor, Xinjiang associated with burials from 3261 B.P.

Ephedra, a group of mysterious hallucinogenic medicinal plants, has been used in China for a long history. As the excavation work proceeded at Lop Nor, Xinjiang Province of China where the ancient residents attributed to an ancient and isolated autochthonous Asian gene pool used to live, Ephedra was unearthed from Xiaohe Cemetery. The unearthed Ephedra was dated by 14C radiometric dating and identified as E. sinica by morphological, microscopical observation in combination with ultra performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS). Based on the identified chemicals and general aromatic characteristics of the plant, Ephedra may be one of the earliest plants potentially used for corpse embalming or religious worship.

Genetic variation of Scots pine (Pinus sylvestris L.) in Eurasia: impact of postglacial recolonization and human-mediated gene transfer

Key messageThe range-wide level of genetic variation of Scots pine (Pinus sylvestris L.) is geographically structured. High admixture and low genetic structure of populations in Central Europe and Fennoscandia suggest past recolonization from multiple sources and the influence of human-mediated gene transfer. Gene pools of marginal and isolated stands require active conservation. Some areas of Scots pine distribution need further genetic studies.ContextScots pine (Pinus sylvestris L.) seems to be a species of low conservation priority because it has a very wide Eurasian distribution and plays a leading role in many forest tree breeding programs. Nevertheless, considering its economic value, long breeding history, range fragmentation, and increased mortality, which is also projected in the future, it requires a more detailed description of its genetic resources.AimsOur goal was to compare patterns of genetic variation found in biparentally inherited nuclear DNA with previous research carried out with mitochondrial and chloroplast DNA due to their different modes of transmission.MethodsWe analyzed the genetic variation and relationships of 60 populations across the distribution of Scots pine in Eurasia (1262 individuals) using a set of nuclear DNA markers.ResultsWe confirmed the high genetic variation and low genetic differentiation of Scots pine spanning large geographical areas. Nevertheless, there was a clear division between European and Asian gene pools. The genetic variation of Asian populations was lower than in Europe. Spain, Turkey, and the Apennines constituted separate gene pools, the latter showing the lowest values of all genetic variation parameters. The analyses showed that most populations experienced genetic bottlenecks in the distant past. Ongoing admixture was found in Fennoscandia.ConclusionsOur results suggest a much simpler recolonization history of the Asian than European part of the Scots pine distribution, with migration from limited sources and possible founder effects. Eastern European stands seem to have descended from the Urals refugium. It appears that Central Europe and Fennoscandia share at least one glacial refugium in the Balkans and migrants from higher latitudes, as well as from south-eastern regions. The low genetic structure between Central Europe and Fennoscandia, along with their high genetic admixture, may result at least partially from past human activities related to the transfer of germplasm in the nineteenth and early twentieth centuries. In light of ongoing climate changes and projected range shifts of Scots pine, conservation strategies are especially needed for marginal and isolated stands of this species. Genetic research should also be complemented in parts of the species distribution that have thus far been poorly studied.

Dual origins of the Northwest Chinese Kyrgyz: the admixture of Bronze age Siberian and Medieval Niru'un Mongolian Y chromosomes.

The Kyrgyz are a trans-border ethnic group, mainly living in Kyrgyzstan. Previous genetic investigations of Central Asian populations have repeatedly investigated the Central Asian Kyrgyz. However, from the standpoint of human evolution and genetic diversity, Northwest Chinese Kyrgyz is one of the more poorly studied populations. In this study, we analyzed the non-recombining portion of the Y-chromosome from 298 male Kyrgyz samples from Xinjiang Uygur Autonomous Region in northwestern China, using a high-resolution analysis of 108 biallelic markers and 17 or 24 STRs. First, via a Y-SNP-based PCA plot, Northwest Chinese Kyrgyz tended to cluster with other Kyrgyz population and are located in the West Asian and Central Asian group. Second, we found that the Northwest Chinese Kyrgyz display a high proportion of Y-lineage R1a1a1b2a2a-Z2125, related to Bronze Age Siberian, and followed by Y-lineage C2b1a3a1-F3796, related to Medieval Niru'un Mongols, such as Uissun tribe from Kazakhs. In these two dominant lineages, two unique recent descent clusters have been detected via NETWORK analysis, respectively, but they have nearly the same TMRCA ages (about 13th-14th centuries). This finding once again shows that the expansions of Mongol Empire had a striking effect on the Central Asian gene pool.

Red blood cell frequencies and genetic polymorphisms of various blood grouping systems in the emirati population

AbstractBackground and objectivesData on the frequencies of RBC antigens and their variants in the Arab world are limited. Thus, determining the antigenic profile of the United Arab Emirates (UAE) population by serologic and molecular methods is significant to enhance operational efficiency in donor centres and transfusion services.Study design and methodsThe study is a retrospective retrieval of serologic and genotype data. The serological ABO type data of 30 954 UAE national donors, the serological RHD and RHCE data of 10 036 UAE national donors, and the genotype data of 354 patients and donors of admixed nationalities for determining different blood group systems were retrieved and analysed.ResultsRh D negative (dccee) phenotype in the UAE national donor population is lower compared to the reported Rh D negative phenotype in the European population (6·8% vs. 18%) and there were a high number of variants observed in the patient and donor populations, especially in the RhCE and Duffy blood group systems (12·1% and 59·3%, respectively).ConclusionHigh number of variants and rare blood group profiles were observed and the gene pool of the Emirati nationals, as well as their antigenic frequencies, is an intermediate between the European and African populations rather than the Asian gene pool.

An Ancient Genome from the Indus Valley Civilization

Shinde etal. report the first genome-wide data from an ancient individual from the Indus Valley Civilization in South Asia. Their findings have implications for the origins and spread of farming and Indo-European languages in the region and the makings of the South Asian gene pool.

Untangling Neolithic and Bronze Age mitochondrial lineages in South Asia

Two key moments shaped the extant South Asian gene pool within the last 10 thousand years (ka): the Neolithic period, with the advent of agriculture and the rise of the Harappan/Indus Valley Civilisation; and Late Bronze Age events that witnessed the abrupt fall of the Harappan Civilisation and the arrival of Indo-European speakers. This study focuses on the phylogeographic patterns of mitochondrial haplogroups H2 and H13 in the Indian Subcontinent and incorporates evidence from recently released ancient genomes from Central and South Asia. It found signals of Neolithic arrivals from Iran and later movements in the Bronze Age from Central Asia that derived ultimately from the Steppe. This study shows how a detailed mtDNA phylogeographic approach, combining both modern and ancient variation, can provide evidence of population movements, even in a scenario of strong male bias such as in the case of the Bronze Age Steppe dispersals.

Phylogeography and post‐glacial dynamics in the clonal‐sexual orchid Cypripedium calceolus L.

AbstractAimWe investigated the phylogeographical history of a clonal‐sexual orchid, to test the hypothesis that current patterns of genetic diversity and differentiation retain the traces of climatic fluctuations and of the species reproductive system.LocationEurope, Siberia and Russian Far East.TaxonCypripedium calceolus L. (Orchidaceae).MethodsSamples (>900, from 56 locations) were genotyped at 11 nuclear microsatellite loci and plastid sequences were obtained for a subset of them. Analysis of genetic structure and approximate Bayesian computations were performed. Species distribution modelling was used to explore the effects of past climatic fluctuations on the species range.ResultsAnalysis of genetic diversity reveals high heterozygosity and allele diversity, with no geographical trend. Three genetic clusters are identified with extant gene pools derived from ancestral demes in glacial refugia. Siberian populations exhibit different plastid haplotypes, supporting an early divergence for the Asian gene pool. Demographic results based on genetic data are compatible with an admixture event explaining differentiation in Estonia and Romania and they are consistent with past climatic dynamics inferred through species distribution modelling. Current population differentiation does not follow isolation by distance model and is compatible with a model of isolation by colonization.Main conclusionsThe genetic differentiation observed today in C. calceolus preserves the signature of climatic fluctuations in the historical distribution range of the species. Our findings support the central role of clonal reproduction in the reducing loss of diversity through genetic drift. The dynamics of the clonal‐sexual reproduction are responsible for the persistence of ancestral variation and stability during glacial periods and post‐glacial expansion.

The genetic legacy of the Yaghnobis: A witness of an ancient Eurasian ancestry in the historically reshuffled central Asian gene pool.

The Yaghnobis are an ethno-linguistic minority historically settled along the Yaghnob River in the Upper-Zarafshan Valley in Tajikistan. They speak a language of Old Sogdian origin, which is the only present-day witness of the Lingua Franca used along the Silk Road in Late Antiquity. The aim of this study was to reconstruct the genetic history of this community in order to shed light on its isolation and genetic ancestry within the Euro-Asiatic context. A total of 100 DNA samples were collected in the Yaghnob and Matcha Valleys during several expeditions and their mitochondrial, Y-chromosome and autosomal genome-wide variation were compared with that from a large set of modern and ancient Euro-Asiatic samples. Findings from uniparental markers highlighted the long-term isolation of the Yaghnobis. Mitochondrial DNA ancestry traced an ancient link with Middle Eastern populations, whereas Y-chromosome legacy showed more tight relationships with Central Asians. Admixture, outgroup-f3, and D-statistics computed on autosomal variation corroborated Y-chromosome evidence, pointing respectively to low Anatolian Neolithic and high Steppe ancestry proportions in Yaghnobis, and to their closer affinity with Tajiks than to Iranians. Although the Yaghnobis do not show evident signs of recent admixture, they could be considered a modern proxy for the source of gene flow for many Central Asian and Middle Eastern groups. Accordingly, they seem to retain a peculiar genomic ancestry probably ascribable to an ancient gene pool originally wide spread across a vast area and subsequently reshuffled by distinct demographic events occurred in Middle East and Central Asia.

Y Chromosome Sequences Reveal a Short Beringian Standstill, Rapid Expansion, and early Population structure of Native American Founders

The Americas were the last inhabitable continents to be occupied by humans, with a growing multidisciplinary consensus for entry 15-25 thousand years ago (kya) from northeast Asia via the former Beringia land bridge [1-4]. Autosomal DNA analyses have dated the separation of Native American ancestors from the Asian gene pool to 23 kya or later [5, 6] andmtDNA analyses to ∼25 kya [7], followed by isolation ("Beringian Standstill" [8, 9]) for 2.4-9 ky and then arapid expansion throughout the Americas. Here, we present a calibrated sequence-based analysis of222 Native American and relevant Eurasian Ychromosomes (24 new) from haplogroups Q andC [10], with four major conclusions. First, we identify three to four independent lineages as autochthonous and likely founders: the major Q-M3 and rarer Q-CTS1780 present throughout the Americas, the very rare C3-MPB373 in South America, and possibly the C3-P39/Z30536 in North America. Second, from the divergence times and Eurasian/Americandistribution of lineages, we estimate a Beringian Standstill duration of 2.7 ky or 4.6 ky, according to alternative models, and entry south of the ice sheet after 19.5 kya. Third, we describe thestar-like expansion of Q-M848 (within Q-M3) starting at 15 kya [11] in the Americas, followed by establishment of substantial spatial structure in South Americaby 12 kya. Fourth, the deep branches of theQ-CTS1780 lineage present at low frequencies throughout the Americas today [12] may reflect a separate out-of-Beringia dispersal after the melting of the glaciers at the end of the Pleistocene.

Conserving and Sharing Taro Genetic Resources for the Benefit of Global Taro Cultivation: A Core Contribution of the Centre for Pacific Crops and Trees.

This review article gives an account of the origin, domestication, and dispersal of taro, a staple food crop in many countries in the humid tropics and subtropics. Genetic diversity studies indicated that distinct gene pools exist in all the regions where taro may be naturally distributed—the Indian subcontinent, China, Southeast Asia, and in Oceania. The Asian gene pool presented the highest genetic diversity. Diploid taro is prevalent in the Pacific Islands, while both diploids and triploids are found in mainland Asia. Triploids are thought to provide better adaptability and enhanced hardiness to higher altitudes and latitudes where sexual reproduction is not viable. The Centre for Pacific Crops and Trees (CePaCT) conserves in vitro close to 70% of the taro genetic resources held ex situ and is therefore considered the world center for taro genetic resources. Phytophthora colocasiae or taro leaf blight (TLB) is the most severe disease of taro' causing 25%–50% yield losses and postharvest decay of corms. The CePaCT genebank supported the participatory TLB breeding program in Samoa through the provision of diverse taro germplasm from the Asian gene pool. However, CePaCT not only serves taro producers in the Pacific but also shares new allelic diversity of taro globally. More recent distributions of taro genetic diversity to West and Central Africa were in response to an outbreak and spread of TLB in West Africa. Global dissemination of taro genetic diversity is assisting producer countries in the process of adaptation to emerging biotic and abiotic stresses, exacerbated by climate change.

Effective Genomic Selection in a Narrow-Genepool Crop with Low-Density Markers: Asian Rapeseed as an Example.

Genomic selection (GS) has revolutionized breeding for quantitative traits in plants, offering potential to optimize resource allocation in breeding programs and increase genetic gain per unit of time. Modern high-density single nucleotide polymorphism (SNP) arrays comprising up to several hundred thousand markers provide a user-friendly technology to characterize the genetic constitution of whole populations and for implementing GS in breeding programs. However, GS does not build upon detailed genotype profiling facilitated by maximum marker density. With extensive genome-wide linkage disequilibrium (LD) being a common characteristic of breeding pools, fewer representative markers from available high-density genotyping platforms could be sufficient to capture the association between a genomic region and a phenotypic trait. To examine the effects of reduced marker density on genomic prediction accuracy, we collected data on three traits across 2 yr in a panel of 203 homozygous Chinese semiwinter rapeseed ( L.) inbred lines, broadly encompassing allelic variability in the Asian genepool. We investigated two approaches to selecting subsets of markers: a trait-dependent strategy based on genome-wide association study (GWAS) significance thresholds and a trait-independent method to detect representative tag SNPs. Prediction accuracies were evaluated using cross-validation with ridge-regression best linear unbiased predictions (rrBLUP). With semiwinter rapeseed as a model species, we demonstrate that low-density marker sets comprising a few hundred to a few thousand markers enable high prediction accuracies in breeding populations with strong LD comparable to those achieved with high-density arrays. Our results are valuable for facilitating routine application of cost-efficient GS in breeding programs.

Obesity genetics: insights from the Pakistani population.

The Pakistani population is extensively diverse, indicating a genetic admixture of European and Central/West Asian migrants with indigenous South Asian gene pools. Pakistanis are organized in different ethnicities/castes based on cultural, linguistic and geographical origin. While Pakistan is facing a rapid nutritional transition, the rising prevalence of obesity is driving a growing burden of health complications and mortality. This represents a unique opportunity for the research community to study the interplay between obesogenic environmental changes and obesity predisposing genes in the time frame of one generation. This review recapitulates the ancestral origins of Pakistani population, the societal determinants of the rise in obesity and its governmental management. We describe the contribution of syndromic, monogenic non-syndromic and polygenic obesity genes identified in the Pakistani population. We then discuss the utility of gene identification approaches based on large consanguineous families and original gene×environment interaction study designs in discovering new obesity genes and causal pathways. Elucidation of the genetic basis of obesity in the Pakistani population may result in improved methods of obesity prevention and treatment globally.

Epidemic Clones, Oceanic Gene Pools, and Eco-LD in the Free Living Marine Pathogen Vibrio parahaemolyticus.

We investigated global patterns of variation in 157 whole-genome sequences of Vibrio parahaemolyticus, a free-living and seafood associated marine bacterium. Pandemic clones, responsible for recent outbreaks of gastroenteritis in humans, have spread globally. However, there are oceanic gene pools, one located in the oceans surrounding Asia and another in the Mexican Gulf. Frequent recombination means that most isolates have acquired the genetic profile of their current location. We investigated the genetic structure in the Asian gene pool by calculating the effective population size in two different ways. Under standard neutral models, the two estimates should give similar answers but we found a 27-fold difference. We propose that this discrepancy is caused by the subdivision of the species into a hundred or more ecotypes which are maintained stably in the population. To investigate the genetic factors involved, we used 51 unrelated isolates to conduct a genome-wide scan for epistatically interacting loci. We found a single example of strong epistasis between distant genome regions. A majority of strains had a type VI secretion system associated with bacterial killing. The remaining strains had genes associated with biofilm formation and regulated by cyclic dimeric GMP signaling. All strains had one or other of the two systems and none of isolate had complete complements of both systems, although several strains had remnants. Further "top down" analysis of patterns of linkage disequilibrium within frequently recombining species will allow a detailed understanding of how selection acts to structure the pattern of variation within natural bacterial populations.

Tracing Arab-Islamic Inheritance in Madagascar: Study of the Y-chromosome and Mitochondrial DNA in the Antemoro

Madagascar is located at the crossroads of the Asian and African worlds and is therefore of particular interest for studies on human population migration. Within the large human diversity of the Great Island, we focused our study on a particular ethnic group, the Antemoro. Their culture presents an important Arab-Islamic influence, but the question of an Arab biological inheritance remains unresolved. We analyzed paternal (n=129) and maternal (n=135) lineages of this ethnic group. Although the majority of Antemoro genetic ancestry comes from sub-Saharan African and Southeast Asian gene pools, we observed in their paternal lineages two specific haplogroups (J1 and T1) linked to Middle Eastern origins. This inheritance was restricted to some Antemoro sub-groups. Statistical analyses tended to confirm significant Middle Eastern genetic contribution. This study gives a new perspective to the large human genetic diversity in Madagascar.

The Hmong Diaspora: Preserved South-East Asian genetic ancestry in French Guianese Asians

The Hmong Diaspora is one of the widest modern human migrations. Mainly localised in South-East Asia, the United States of America, and metropolitan France, a small community has also settled the Amazonian forest of French Guiana. We have biologically analysed 62 individuals of this unique Guianese population through three complementary genetic markers: mitochondrial DNA (HVS-I/II and coding region SNPs), Y-chromosome (SNPs and STRs), and the Gm allotypic system. All genetic systems showed a high conservation of the Asian gene pool (Asian ancestry: mtDNA=100.0%; NRY=99.1%; Gm=96.6%), without a trace of founder effect. When compared across various Asian populations, the highest correlations were observed with Hmong-Mien groups still living in South-East Asia (Fst<0.05; P-value<0.05). Despite a long history punctuated by exodus, the French Guianese Hmong have maintained their original genetic diversity.

Genetic diversity of carrot (Daucus carota L.) cultivars revealed by analysis of SSR loci

Polymorphism of simple sequence repeat (SSR) loci was assessed in a collection of 88 carrot (Daucus carota L. subsp. sativus Hoffm.) accessions. The collection comprised cultivars and landraces mainly from Asia, Europe, and North America. Plants were grown in the glasshouse and characterized for root color and shape. Thirty SSR loci were fully characterized using parameters derived from allele frequencies, i.e. the number of total, effective and rare alleles, the observed and expected heterozygosity, and fixation index. Using a Bayesian approach, two clusters of 17 and 61 accessions were distinguished, which comprised the Asian and Western type accessions, respectively. Genetic diversity of the Asian gene pool was higher than that of the Western gene pool. The results of SSR analysis were supported by morphological characterization, and are congruent with current knowledge on the history of carrot domestication and breeding.

Extending the rapeseed genepool with resynthesized Brassica napus L. I: Genetic diversity

Resynthesized Brassica napus L. could be employed to increase the genetic variation in the narrow oilseed rape genepool and to establish a genetically distant genepool for hybrid breeding. One important criterion for selecting appropriate resynthesized lines is their genetic distance to adapted breeding material. In this study we estimated the genetic distances in a wide collection of 142 resynthesized lines and 57 winter and spring rapeseed cultivars from Europe, North America and Asia using RFLP marker data. The highest in-group genetic distance (0.36) was observed in 142 resynthesized lines compared to 0.21 in winter, 0.23 in summer, and 0.28 in Asian genotypes. The group of adapted breeding material clustered into three groups of winter-, spring-type, and Asian genotypes. Resynthesized lines did not form distinct subgroups in the cluster analysis, but large differences were revealed in the genetic distance of resynthesized lines to the adapted winter oilseed rape genepool. The highest distance to winter oilseed rape was found in resynthesized lines with parental lines from the Asian genepool as B. oleracea convar. botrytis var. alboglabra (Bail.) Sun or B. rapa ssp. chinensis (L.) Hanelt.

Genetic diversity and linkage disequilibrium studies on a 3.1-Mb genomic region of chromosome 3B in European and Asian bread wheat (Triticum aestivum L.) populations

Genetic diversity and linkage disequilibrium (LD) were investigated in 376 Asian and European accessions of bread wheat (Triticum aestivum L.). After a first and rapid screening about diversity and genetic structure at the whole genome scale using 70 simple sequence repeats (SSRs), we focused on a sequenced contig (ctg954) of 3.1 Mb located on the short arm of chromosome 3B of cv. Chinese Spring, using 32 SSRs and 10 single nucleotide polymorphisms. This contig is part of a multiple fungal resistance region. Mean polymorphism information content value on the 32 SSRs was slightly higher in the Asian genepool (0.396) than that for the European (0.329) pool. Compared with results at the whole genome scale, data from this 3.1-Mb region indicated similar trends in genetic diversity indices between both genepools. Population structure and molecular variance analyses demonstrated significant genetic differentiation and geographical subdivision in both groups of accessions. Concerning LD at the contig level, the European population had a significantly higher mean r(2) value (0.23) than the Asian population (0.18), indicating a stronger LD in the European material. With a mean of 1 marker every 74 kb, the resolution reached here allowed to perform a detailed comparative analysis of the LD and genetic diversity along the complete 3.1-Mb region in both genepools. A sliding-window approach revealed some interesting regions of the contig where LD is increasing when genetic diversity is decreasing. This study provides an in-depth understanding of molecular population genetics in European and Asian wheat gene pools, and prospects for association mapping of important sources of fungal disease resistance.

Haplotype-Sharing Analysis Showing Uyghurs Are Unlikely Genetic Donors

The Uyghur (UIG) are a group of people primarily residing in Xinjiang of China, which is geographically located in Central Asia, from where modern humans were presumably spread in all directions reaching Europe, east, and northeast Asia about 40 kya. A recent study suggested that the UIG are ancestry donors of the East Asian (EAS) gene pool. However, an alternative hypothesis, that is, the UIG is an admixture population with both EAS and EUR ancestries is also supported by our previous studies. To test the two competing hypotheses, here we conducted a haplotype-sharing analysis (HSA) based on empirical and simulated data of high-density single nucleotide polymorphisms. Our results showed that more than 95% of UIG haplotypes could be found in either EAS or EUR populations, which contradicts the expectation of the null models assuming that UIG are donors. Simulation studies further indicated that the proportion of UIG private haplotypes observed in empirical data is only expected in alternative models assuming that UIG is an admixture population. Interestingly, the estimated ancestry contribution of 44%:56% (EAS:EUR) based on HSA is consistent with our previous estimation with STRUCTURE analysis. Although the history of UIGs could be complex, our method is explicit and conservative in rejecting the null hypothesis. We concluded that the gene pool of modern UIGs is more likely a sole recipient with contribution from both EAS and EUR.

EXPLOITATION OF THE GENETIC DIVERSITY: AN APPROACH TO ELUCIDATE RESISTANCE

Downy and powdery mildew, the two most threatening fungal diseases affecting grapevine cultivars are caused by Plasmopara viticola and Uncinula necator. Resistance to these pathogens is exclusively found in North-American and Asian genepools of Vitis which represent valuable genetic resources for resistance breeding. To get a better understanding of the complex mechanisms of resistance and quality parameters at the molecular level, the genetic diversity of a representative collection of Vitis accessions including various interspecific hybrids and Vitis species is being studied in a trilateral cooperation including Germany (Geilweilerhof), France (Genoplante), and Spain (MCyT). The first step is the establishment of a European grapevine CoreCollection comprising a maximum of allelic and phenotypic diversity represented within the collections of the three countries located at Montpellier (F), El Encin (E), and Siebeldingen (D). Genotyping of grapevine accessions is performed using a set of 20 microsatellites evenly distributed throughout the genome. The evaluation of the phenotypic data is based on internationally accepted OIV descriptors for Plasmopara viticola and Uncinula necator resistance. In the near future, the European Vitis CoreCollection will allow us to identify allelic variants of candidate genes for these traits and to elucidate the extent of nucleotide diversity. This project will construct a well-defined characterized Vitis CoreCollection and generate a valuable instrument for the extended use of the naturally existing variability in the Vitis gene pool.