The Puzzle of Rice Domestication

The origin of cultivated rice has puzzled plant biologists for decades. This is due, at least in part, to the complex evolutionary dynamics in rice cultivars and wild progenitors, particularly rapid adaptive differentiation and continuous gene flow within and between cultivated and wild rice. The long-standing controversy over single versus multiple and annual versus perennial origins of cultivated rice has been brought into shaper focus with the rapid accumulation of genetic and phylogenetic data. Molecular phylogenetic analyses revealed ancient genomic differentiation between rice cultivars, suggesting that they were domesticated from divergent wild populations. However, the recently cloned domestication gene sh4, responsible for the reduction of grain shattering from wild to cultivated rice, seems to have originated only once. Herein, we propose two models to reconcile apparently conflicting evidence regarding rice domestication. The snowoballing model considers a single origin of cultivated rice. In this model, a core of critical domestication alleles was fixed in the founding cultivar and then acted to increase the genetic diversity of cultivars through hybridization with wild populations. The combination model considers multiple origins of cultivated rice. In this model, Initial cultivars were domesticated from divergent wild populations and fixed different sets of domestication alleles. Subsequent crosses among these semi-domesticated cultivars resulted in the fixation of a similar set of critical domestication alleles in the contemporary cultivars. In both models, introgression has played an important role in rice domestication. Recent and future introgression of beneficial genes from the wild gene pool through conventional and molecular breeding programs can be viewed as the continuation of domestication.     

Diversity and evolution of rice progenitors in Australia

In the thousands of years of rice domestication in Asia, many useful genes have been lost from the gene pool. Wild rice is a key source of diversity for domesticated rice. Genome sequencing has suggested that the wild rice populations in northern Australia may include novel taxa, within the AA genome group of close (interfertile) wild relatives of domesticated rice that have evolved independently due to geographic separation and been isolated from the loss of diversity associated with gene flow from the large populations of domesticated rice in Asia. Australian wild rice was collected from 27 sites from Townsville to the northern tip of Cape York. Whole chloroplast genome sequences and 4,555 nuclear gene sequences (more than 8 Mbp) were used to explore genetic relationships between these populations and other wild and domesticated rices. Analysis of the chloroplast and nuclear data showed very clear evidence of distinctness from other AA genome Oryza species with significant divergence between Australian populations. Phylogenetic analysis suggested the Australian populations represent the earliest‐branching AA genome lineages and may be critical resources for global rice food security. Nuclear genome analysis demonstrated that the diverse O. meridionalis populations were sister to all other AA genome taxa while the Australian O. rufipogon‐like populations were associated with the clade that included domesticated rice. Populations of apparent hybrids between the taxa were also identified suggesting ongoing dynamic evolution of wild rice in Australia. These introgressions model events similar to those likely to have been involved in the domestication of rice.     

A simulation of the effect of inbreeding on crop domestication genetics with comments on the integration of archaeobotany and genetics: a reply to Honne and Heun

Archaeobotanical evidence for Near Eastern einkorn wheat, barley, and Chinese rice suggests that the fixation of key domestication traits such as non-shattering was slower than has often been assumed. This suggests a protracted period of pre-domestication cultivation, and therefore implies that both in time and in space the initial start of cultivation was separated from eventual domestication, when domesticated and wild populations would have become distinct gene pools. Archaeobotanical evidence increasingly suggests more pathways to cultivation than are represented by modern domesticated crop lines, including apparent early experiments with cultivation that did not lead to domestication, and early domesticates, such as two-grained einkorn and striate-emmeroid wheats, which went extinct in prehistory. This diverse range of early crops is hard to accommodate within a single centre of origin for all early Near Eastern cultivars, despite suggestions from genetic datasets that single origins from a single centre ought to be expected. This apparent discrepancy between archaeobotany and genetics highlights the need for modelling the expected genetic signature of different domestication scenarios, including multiple origins. A computer simulation of simple plant populations with 20 chromosomes was designed to explore potential differences between single and double origins of domesticated populations as they might appear in genomic datasets millennia later. Here we report a new simulation of a self-pollinating (2% outbreeding) plant compared to panmictic populations, and find that the general outcome is similar with multiple starts of cultivation drifting towards apparent monophyly in genome-wide phylogenetic analysis over hundreds of generations. This suggests that multiple origins of cultivation of a given species may be missed in some forms of modern genetic analysis, and it highlights the need for more complex modelling of population genetic processes associated with the origins of agriculture.     

Wild to crop introgression and genetic diversity in Lima bean (Phaseolus lunatus L.) in traditional Mayan milpas from Mexico

Despite the evolutionary, ecological and economic importance of introgression between a domesticated species and its wild relatives in centers of diversity and domestication, the role of traditional farmers in this process has received limited attention. In the Yucatan Peninsula, the region of Mexico that has the greatest amount of domesticated varieties of Lima bean, wild populations grow sympatrically with conspecific varieties, allowing the Mayan farmer to act directly on introgressed seed. We used 11 microsatellite loci to assess levels of introgression in three wild-domesticated complexes of Lima bean from the Yucatan Peninsula and analyze its impact on the genetic diversity of this crop. structure and InStruct analyses showed similar results. The Instruct analysis indicated that the complex with the lowest level of introgression was one where the farmer actively selected against wild plants and introgressed seed. In contrast, the complex with the highest level of introgression was one where the farmer has been consciously selecting a weedy morphotype for 15 years and has already incorporated it into his diet. Genetic diversity of the domesticated pool was higher in the complex with the higher level of introgression. This study showed that farmers have an important role in limiting or favoring the wild to crop introgression and influencing the levels of genetic diversity in their domesticated pool. Only when traditional farmers’ knowledge is taken into account can we correctly understand the dynamics, generation and maintenance of genetic diversity of the landraces in the centers of diversity and domestication.     

Chloroplast DNA variation confirms a single origin of domesticated sunflower (Helianthus annuus L.)

Although sunflower was long thought to be the product of a single domestication in what is now the east-central United States, recent archaeological and genetic evidence have suggested the possibility of an independent origin of domestication, perhaps in Mexico. We therefore used hypervariable chloroplast simple-sequence repeat markers to search for evidence of a possible Mexican origin of domestication. This work resulted in the identification of 45 chloroplast haplotypes from 26 populations across the range of wild sunflower as well as 3 haplotypes from 15 domesticated lines, representing both primitive and improved cultivars. The 3 domesticated haplotypes were characterized by 1 primary haplotype (found at a frequency of 6.7% in the wild) as well as 2 rare haplotypes, which are most likely the products of mutation or introgression. One of these rare haplotypes was not observed in the wild, bringing the total number of haplotypes identified to 46. A principal coordinate analysis revealed the presence of 3 major haplotype clusters, one of which contained the primary domesticated haplotype, the 2 rare domesticated variants, as well as haplotypes found across much of the range of wild sunflower. The Mexican haplotypes, on the other hand, fell well outside of this cluster. Although our data do not provide insight into the specific location of sunflower domestication, the relative rarity of the primary domesticated haplotype in the wild, combined with the dissimilarity between this haplotype and those found in the Mexican populations surveyed, provides further evidence that the extant domesticated sunflowers are the product of a single domestication event somewhere outside of Mexico.     

New insights into the history of rice domestication

The history of rice domestication has long been a subject of debate. Recently obtained genetic evidence provides new insights into this complex story. Genome-wide studies of variation demonstrate that the two varietal groups in Oryza sativa (indica and japonica) arose from genetically distinct gene pools within a common wild ancestor, Oryza rufipogon, suggesting multiple domestications of O. sativa. However, the evolutionary history of recently cloned domestication genes adds another layer of complexity to the domestication of rice. Although some alleles exist only within specific subpopulations, as would be expected if the domestications occurred independently, other major domestication alleles are common to all cultivated O. sativa varieties. Our current view of rice domestication supports multiple domestications coupled with limited introgression that transferred key domestication alleles between divergent rice gene pools.     

Study of genetic relationships between wild and domesticated grapevine distributed from Middle East Regions to European countries

Archaeobotanical-archaeological, cultural and historical data indicate that grapevine domestication can be dated back from 6000 to 7000 years ago and that it took place in the Caucasian and Middle East Regions. However, events leading to the domestication of this crop species are still an open issue. In this paper, 6 chloroplast microsatellites have been used to assess genetic similarities among, and within, domesticated and wild grapevine accessions representative of 7 distinct geographical regions from the Middle-East to Western Europe. Results show that 2 out of the 6 analyzed chloroplast loci are polymorphic within the 193 domesticated individuals and the 387 samples of 69 wild populations. Allele variants of the Cp-SSR loci combine in a total of 6 different haplotypes. The data show that the haplotype distribution is not homogeneous: the 6 haplotypes are present in the domesticated varieties, but only 5 (haplotype VI is absent) are observed in wild populations. The analysis of haplotype distribution allows discussion of the relationships between the two grape subspecies. The contribution of the wild grape germplasm to the domesticated gene pool still growing in different geographical regions can be, in cases, made evident, suggesting that beside domestication, gene introgression has also played a role in shaping the current varietal landscape of the European viticulture.

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Malaysian weedy rice shows its true stripes: wild Oryza and elite rice cultivars shape agricultural weed evolution in Southeast Asia

Weedy rice is a close relative of domesticated rice (Oryza sativa) that competes aggressively with the crop and limits rice productivity worldwide. Most genetic studies of weedy rice have focused on populations in regions where no reproductively compatible wild Oryza species occur (North America, Europe and northern Asia). Here, we examined the population genetics of weedy rice in Malaysia, where wild rice (O. rufipogon) can be found growing in close proximity to cultivated and weedy rice. Using 375 accessions and a combined analysis of 24 neutral SSR loci and two rice domestication genes (sh4, controlling seed shattering, and Bh4, controlling hull colour), we addressed the following questions: (i) What is the relationship of Malaysian weedy rice to domesticated and wild rice, and to weedy rice strains in the USA? (ii) To what extent does the presence of O. rufipogon influence the genetic and phenotypic diversity of Malaysian weeds? (iii) What do the distributions of sh4 and Bh4 alleles and associated phenotypes reveal about the origin and contemporary evolution of Malaysian weedy rice? Our results reveal the following: independent evolutionary origins for Malaysian weeds and US strains, despite their very close phenotypic resemblance; wild‐to‐weed gene flow in Malaysian weed populations, including apparent adaptive introgression of seed‐shattering alleles; and a prominent role for modern Malaysian cultivars in the origin and recent proliferation of Malaysian weeds. These findings suggest that the genetic complexity and adaptability of weedy crop relatives can be profoundly influenced by proximity to reproductively compatible wild and domesticated populations.     

A genome-wide analysis of differentiation between wild and domesticated Phaseolus vulgaris from Mesoamerica

Lack of introgression or divergent selection may be responsible for the maintenance of phenotypic differences between sympatric populations of crops and their wild progenitors. To distinguish between these hypotheses, amplified fragment length polymorphism markers were located on a molecular linkage map of Phaseolus vulgaris relative to genes for the domestication syndrome and other traits. Diversity for these same markers was then analyzed in two samples of wild and domesticated populations from Mesoamerica. Differentiation between wild and domesticated populations was significantly higher in parapatric and allopatric populations compared to sympatric populations. It was also significantly higher near genes for domestication compared to those away from these genes. Concurrently, the differences in genetic diversity between wild and domesticated populations were strongest around such genes. These data suggest that selection in the presence of introgression appears to be a major evolutionary factor maintaining the identity of wild and domesticated populations in sympatric situations. Furthermore, alleles from domesticated populations appear to have displaced alleles in sympatric wild populations, thus leading to a reduction in genetic diversity in such populations. These results also provide a possible experimental framework for assessing the long-term risk of transgene escape and the targeting of transgenes inside the genome to minimize the survival of these transgenes into wild populations following introduction by gene flow.This article is dedicated to the memory of Epimaki M. K. Koinange.     

The role of Bh4 in parallel evolution of hull colour in domesticated and weedy rice

The two independent domestication events in the genus Oryza that led to African and Asian rice offer an extremely useful system for studying the genetic basis of parallel evolution. This system is also characterized by parallel de‐domestication events, with two genetically distinct weedy rice biotypes in the US derived from the Asian domesticate. One important trait that has been altered by rice domestication and de‐domestication is hull colour. The wild progenitors of the two cultivated rice species have predominantly black‐coloured hulls, as does one of the two U.S. weed biotypes; both cultivated species and one of the US weedy biotypes are characterized by straw‐coloured hulls. Using Black hull 4 (Bh4) as a hull colour candidate gene, we examined DNA sequence variation at this locus to study the parallel evolution of hull colour variation in the domesticated and weedy rice system. We find that independent Bh4‐coding mutations have arisen in African and Asian rice that are correlated with the straw hull phenotype, suggesting that the same gene is responsible for parallel trait evolution. For the U.S. weeds, Bh4 haplotype sequences support current hypotheses on the phylogenetic relationship between the two biotypes and domesticated Asian rice; straw hull weeds are most similar to indica crops, and black hull weeds are most similar to aus crops. Tests for selection indicate that Asian crops and straw hull weeds deviate from neutrality at this gene, suggesting possible selection on Bh4 during both rice domestication and de‐domestication.     

The structure of wild and domesticated emmer wheat populations,gene flow between them,and the site of emmer domestication

The domestication of emmer wheat (Triticum turgidum spp. dicoccoides, genomes BBAA) was one of the key events during the emergence of agriculture in southwestern Asia, and was a prerequisite for the evolution of durum and common wheat. Single- and multilocus genotypes based on restriction fragment length polymorphism at 131 loci were analyzed to describe the structure of populations of wild and domesticated emmer and to generate a picture of emmer domestication and its subsequent diffusion across Asia, Europe and Africa. Wild emmer consists of two populations, southern and northern, each further subdivided. Domesticated emmer mirrors the geographic subdivision of wild emmer into the northern and southern populations and also shows an additional structure in both regions. Gene flow between wild and domesticated emmer occurred across the entire area of wild emmer distribution. Emmer was likely domesticated in the Diyarbakir region in southeastern Turkey, which was followed by subsequent hybridization and introgression from wild to domesticated emmer in southern Levant. A less likely scenario is that emmer was domesticated independently in the Diyarbakir region and southern Levant, and the Levantine genepool was absorbed into the genepool of domesticated emmer diffusing from southeastern Turkey. Durum wheat is closely related to domesticated emmer in the eastern Mediterranean and likely originated there. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

New insight into the history of domesticated apple: secondary contribution of the European wild apple to the genome of cultivated varieties

The apple is the most common and culturally important fruit crop of temperate areas. The elucidation of its origin and domestication history is therefore of great interest. The wild Central Asian species Malus sieversii has previously been identified as the main contributor to the genome of the cultivated apple (Malus domestica), on the basis of morphological, molecular, and historical evidence. The possible contribution of other wild species present along the Silk Route running from Asia to Western Europe remains a matter of debate, particularly with respect to the contribution of the European wild apple. We used microsatellite markers and an unprecedented large sampling of five Malus species throughout Eurasia (839 accessions from China to Spain) to show that multiple species have contributed to the genetic makeup of domesticated apples. The wild European crabapple M. sylvestris, in particular, was a major secondary contributor. Bidirectional gene flow between the domesticated apple and the European crabapple resulted in the current M. domestica being genetically more closely related to this species than to its Central Asian progenitor, M. sieversii. We found no evidence of a domestication bottleneck or clonal population structure in apples, despite the use of vegetative propagation by grafting. We show that the evolution of domesticated apples occurred over a long time period and involved more than one wild species. Our results support the view that self-incompatibility, a long lifespan, and cultural practices such as selection from open-pollinated seeds have facilitated introgression from wild relatives and the maintenance of genetic variation during domestication. This combination of processes may account for the diversification of several long-lived perennial crops, yielding domestication patterns different from those observed for annual species.     

Molecular Population Genetics of Rice Domestication

Domestication is a selection process that genetically modifies species to meet human needs. A most intriguing feature of domestication is the extreme phenotypic diversification among breeds. What could be the ultimate source of such genetic variations? Another notable outcome of artificial selection is the reduction in the fitness of domesticated species when they live in the wild without human assistance. The complete sequences of the two subspecies of rice cultivars provide an opportunity to address these questions. Between the two subspecies, we found much higher rates of non‐synonymous (N) than synonymous (S) substitutions and the N/S ratios are higher between cultivars than between wild species. Most interestingly, substitutions of highly dissimilar amino acids that are deleterious and uncommon between natural species are disproportionately common between the two subspecies of rice. We suggest strong selection in the absence of effective recombination may be the driving force, which we called the domestication‐associated Hill‐Robertson effect. These hitchhiking mutations may contribute to some fitness reduction in cultivars. Comparisons of the two genomes also reveal the existence of highly divergent regions in the genomes. Haplotypes in these regions often form highly polymorphic linkage blocks that are much older than speciation between wild species. Genes from such regions could contribute to the differences between indica and japonica and are likely to be involved in the diversifying selection under domestication. Their existence suggests that the amount of genetic variation within the single progenitor species Oryza rufipogon may be insufficient to account for the variation among rice cultivars, which may come from a more inclusive gene pool comprising most of the A‐genome wild species. Genes from the highly polymorphic regions also provide strong support for the independent domestication of the two subspecies. The genomic variation in rice has revealing implications for studying the genetic basis of indica‐japonica differentiation under rice domestication and subsequent improvement.     

The complex history of the domestication of rice

BACKGROUND: Rice has been found in archaeological sites dating to 8000 bc, although the date of rice domestication is a matter of continuing debate. Two species of domesticated rice, Oryza sativa (Asian) and Oryza glaberrima (African) are grown globally. Numerous traits separate wild and domesticated rices including changes in: pericarp colour, dormancy, shattering, panicle architecture, tiller number, mating type and number and size of seeds. SCOPE: Genetic studies using diverse methodologies have uncovered a deep population structure within domesticated rice. Two main groups, the indica and japonica subspecies, have been identified with several subpopulations existing within each group. The antiquity of the divide has been estimated at more than 100 000 years ago. This date far precedes domestication, supporting independent domestications of indica and japonica from pre-differentiated pools of the wild ancestor. Crosses between subspecies display sterility and segregate for domestication traits, indicating that different populations are fixed for different networks of alleles conditioning these traits. Numerous domestication QTLs have been identified in crosses between the subspecies and in crosses between wild and domesticated accessions of rice. Many of the QTLs cluster in the same genomic regions, suggesting that a single gene with pleiotropic effects or that closely linked clusters of genes underlie these QTL. Recently, several domestication loci have been cloned from rice, including the gene controlling pericarp colour and two loci for shattering. The distribution and evolutionary history of these genes gives insight into the domestication process and the relationship between the subspecies. CONCLUSIONS: The evolutionary history of rice is complex, but recent work has shed light on the genetics of the transition from wild (O. rufipogon and O. nivara) to domesticated (O. sativa) rice. The types of genes involved and the geographic and genetic distribution of alleles will allow scientists to better understand our ancestors and breed better rice for our descendents.     

The accumulation of deleterious mutations in rice genomes: a hypothesis on the cost of domestication

The extent of molecular differentiation between domesticated animals or plants and their wild relatives is postulated to be small. The availability of the complete genome sequences of two subspecies of the Asian rice, Oryza sativa (indica and japonica) and their wild relatives have provided an unprecedented opportunity to study divergence following domestication. We observed significantly more amino acid substitutions during rice domestication than can be expected from a comparison among wild species. This excess is disproportionately larger for the more radical kinds of amino acid changes (e.g. Cys<-->Tyr). We estimate that approximately a quarter of the amino acid differences between rice cultivars are deleterious, not accountable by the relaxation of selective constraints. This excess is negatively correlated with the rate of recombination, suggesting that 'hitchhiking' has occurred. We hypothesize that during domestication artificial selection increased the frequency of many deleterious mutations.     

Phylogeny and origin of pearl millet (Pennisetum glaucum [L.] R. Br) as revealed by microsatellite loci

During the last 12,000 years, different cultures around the world have domesticated cereal crops. Several studies investigated the evolutionary history and domestication of cereals such as wheat in the Middle East, rice in Asia or maize in America. The domestication process in Africa has led to the emergence of important cereal crops like pearl millet in Sahelian Africa. In this study, we used 27 microsatellite loci to analyze 84 wild accessions and 355 cultivated accessions originating from the whole pearl millet distribution area in Africa and Asia. We found significantly higher diversity in the wild pearl millet group. The cultivated pearl millet sample possessed 81% of the alleles and 83% of the genetic diversity of the wild pearl millet sample. Using Bayesian approaches, we identified intermediate genotypes between the cultivated and wild groups. We then analyzed the phylogenetic relationship among accessions not showing introgression and found that a monophyletic origin of cultivated pearl millet in West Africa is the most likely scenario supported by our data set.     

Evidences of introgression from cultivated rice to Oryza rufipogon (Poaceae) populations based on SSR fingerprinting: implications for wild rice differentiation and conservation

Crop-to-wild introgression may play an important role in evolution of wild species. Asian cultivated rice (Oryza sativa L.) is of a particular concern because of its cross-compatibility with the wild ancestor, O. rufipogon Griff. The distribution of cultivated rice and O. rufipogon populations is extensively sympatric, particularly in Asia where many wild populations are surrounded by rice fields. Consequently, gene flow from cultivated rice may have a potential to alter genetic composition of wild rice populations in close proximity. In this study, we estimated introgression of cultivated rice with O. rufipogon based on analyses of 139 rice varieties (86 indica and 53 japonica ecotypes) and 336 wild individuals from 11 O. rufipogon populations in China. DNA fingerprinting based on 17 selected rice simple sequence repeat (SSR) primer pairs was adopted to measure allelic frequencies in rice varieties and O. rufipogon samples, and to estimate genetic associations between wild and cultivated rice through cluster analysis. We detected consanguinity of cultivated rice in O. rufipogon populations according to the admixture model of the STRUCTURE program. The analyses showedz that four wild rice populations, DX-P1, DX-P2, GZ-P2, and HL-P, contained some rare alleles that were commonly found in the rice varieties examined. In addition, the four wild rice populations that scattered among the rice varieties in the cluster analysis showed a closer affinity to the cultivars than the other wild populations. This finding supports the contention of substantial gene flow from crop to wild species when these species occur close to each other. The introgressive populations had slightly higher genetic diversity than those that were isolated from rice. Crop-to-wild introgression may have accumulative impacts on genetic variations in wild populations, leading to significant differentiation in wild species. Therefore, effective measure should be taken to avoid considerable introgression from cultivated rice, which may influence the effective in-situ conservation of wild rice species.     

Asymmetry of gene flow and differential geographical structure of molecular diversity in wild and domesticated common bean (<Emphasis Type="Italic">Phaseolus vulgaris</Emphasis> L.) from Mesoamerica

Using amplified fragment length polymorphisms (AFLPs), we analyzed the genetic structure of wild and domesticated common bean (Phaseolus vulgaris L.) from Mesoamerica at different geographical levels to test the hypothesis of asymmetric gene flow and investigate the origin of weedy populations. We showed both by phenetic and admixture population analyses that gene flow is about three- to four-fold higher from domesticated to wild populations than in the reverse direction. This result, combined with other work, points to a displacement of genetic diversity in wild populations due to gene flow from the domesticated populations. The weedy populations appear to be genetically intermediate between domesticated and wild populations, suggesting that they originated by hybridization between wild and domesticated types rather than by escape from cultivation. In addition, the domesticated bean races were genetically similar confirming a single domestication event for the Mesoamerican gene pool. Finally, the genetic diversity of the domesticated bean population showed a lower level of geographic structure in comparison to that of the wild populations.     

Genetic mapping of a new race specific resistance allele effective to Puccinia hordei at the Rph9/Rph12locus on chromosome 5HL in barley

Background

Tea is one of the most popular beverages in the world. Many species in the Thea section of the Camellia genus can be processed for drinking and have been domesticated. However, few investigations have focused on the genetic consequence of domestication and geographic origin of landraces on tea plants using credible wild and planted populations of a single species. Here, C. taliensis provides us with a unique opportunity to explore these issues.

Results

Fourteen nuclear microsatellite loci were employed to determine the genetic diversity and domestication origin of C. taliensis, which were represented by 587 individuals from 25 wild, planted and recently domesticated populations. C. taliensis showed a moderate high level of overall genetic diversity. The greater reduction of genetic diversity and stronger genetic drift were detected in the wild group than in the recently domesticated group, indicating the loss of genetic diversity of wild populations due to overexploitation and habitat fragmentation. Instead of the endangered wild trees, recently domesticated individuals were used to compare with the planted trees for detecting the genetic consequence of domestication. A little and non-significant reduction in genetic diversity was found during domestication. The long life cycle, selection for leaf traits and gene flow between populations will delay the emergence of bottleneck in planted trees. Both phylogenetic and assignment analyses suggested that planted trees may have been domesticated from the adjacent central forest of western Yunnan and dispersed artificially to distant places.

Conclusions

This study contributes to the knowledge about levels and distribution of genetic diversity of C. taliensis and provides new insights into genetic consequence of domestication and geographic origin of planted trees of this species. As an endemic tea source plant, wild, planted and recently domesticated C. taliensis trees should all be protected for their unique genetic characteristics, which are valuable for tea breeding.