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1.
Zhang D Arevalo-Gardini E Mischke S Zúñiga-Cernades L Barreto-Chavez A Del Aguila JA 《Annals of botany》2006,98(3):647-655
BACKGROUND AND AIMS: Cocoa (Theobroma cacao) is indigenous to the Amazon region of South America, and it is well known that the Peruvian Amazon harbours a large number of diverse cocoa populations. A small fraction of the diversity has been collected and maintained as an ex-situ germplasm repository in Peru. However, incorrect labelling of accessions and lack of information on genetic diversity have hindered efficient conservation and use of this germplasm. This study targeted assessment of genetic diversity and population structure in a managed and a semi-natural population. METHODS: Using a capillary electrophoresis genotyping system, 105 cocoa accessions collected from the Huallaga and Ucayali valleys of Peru were fingerprinted. Based on 15 loci SSR profiles, genetic identity was examined for each accession and duplicates identified, population structure assessed and genetic diversity analysed in these two populations. KEY RESULTS: Ten synonymous mislabelled groups were identified among the 105 accessions. The germplasm group in the Huallaga valley was clearly separated from the group in Ucayali valley by the Bayesian assignment test. The Huallaga group has lower genetic diversity, both in terms of allelic richness and of gene diversity, than the Ucayali group. Analysis of molecular variance suggested genetic substructure in the Ucayali group. Significant spatial correlation between genetic distance and geographical distances was detected in the Ucayali group by Mantel tests. CONCLUSIONS: These results substantiate the hypothesis that the Peruvian Amazon hosts a high level of cocoa genetic diversity, and the diversity has a spatial structure. The introduction of exotic seed populations into the Peruvian Amazon is changing the cocoa germplasm spectrum in this region. The spatial structure of cocoa diversity recorded here highlights the need for additional collecting and conservation measures for natural and semi-natural cocoa populations. 相似文献
2.
3.
Geographic and genetic population differentiation of the Amazonian chocolate tree (Theobroma cacao L) 总被引:1,自引:0,他引:1
Motamayor JC Lachenaud P da Silva E Mota JW Loor R Kuhn DN Brown JS Schnell RJ 《PloS one》2008,3(10):e3311
Numerous collecting expeditions of Theobroma cacao L. germplasm have been undertaken in Latin-America. However, most of this germplasm has not contributed to cacao improvement because its relationship to cultivated selections was poorly understood. Germplasm labeling errors have impeded breeding and confounded the interpretation of diversity analyses. To improve the understanding of the origin, classification, and population differentiation within the species, 1241 accessions covering a large geographic sampling were genotyped with 106 microsatellite markers. After discarding mislabeled samples, 10 genetic clusters, as opposed to the two genetic groups traditionally recognized within T. cacao, were found by applying Bayesian statistics. This leads us to propose a new classification of the cacao germplasm that will enhance its management. The results also provide new insights into the diversification of Amazon species in general, with the pattern of differentiation of the populations studied supporting the palaeoarches hypothesis of species diversification. The origin of the traditional cacao cultivars is also enlightened in this study. 相似文献
4.
Cacao (Theobroma cacao L.) has been cultivated in Central America since pre-Columbian times. The type of cacao cultivated in this region was called Criollo; cacao populations from the Amazon basin were called Forastero. The type of Forastero most commonly cultivated until 1950 was named Amelonado. Historical data show Trinitario cacao to have originated in Trinidad, resulting from natural hybridisation between Criollo and Amelonado Forastero. Doubts persist on the source of the Amelonado Forastero involved in the origin of Trinitario; the Amelonado parent may have come from the Lower Amazon, the Orinoco or the Guyanas. Most of the cacao cultivated worldwide until 1950 consisted of Criollo, Trinitario and Amelonado. From the early 1950s, Forastero material collected in the Upper Amazon region during the 1930s and 1940s began to be employed in breeding programmes. To gain a better understanding of the origin and the genetic basis of the cacao cultivars exploited before the utilisation of germplasm collected in the Upper Amazon, a study was carried out using restriction fragment length polymorphism and microsatellite markers. Trinitario samples from 17 countries were analysed. With molecular markers, it was possible to clearly identify three main genotypes (represented by clones SP1, MAT1-6 and SIAL70) implicated in the origin of most Trinitario clones. 相似文献
5.
Dapeng Zhang Sue Mischke Elizabeth S. Johnson Wilbert Phillips-Mora Lyndel Meinhardt 《Tree Genetics & Genomes》2009,5(1):1-10
Plant germplasm collections invariably contain varying levels of genetic redundancy, which hinders the efficient conservation
and utilization of plant germplasm. Reduction of genetic redundancies is an essential step to improve the accuracy and efficiency
of genebank management. The present study targeted the assessment of genetic redundancy and genetic structure in an international
cacao (Theobroma cacao L.) collection maintained in Costa Rica. A total of 688 cacao accessions maintained in this collection were genotyped with
15 simple sequence repeat (SSR) loci, using a capillary electrophoresis genotyping system. The SSR markers provided a high
resolution among the accessions. Thirty-six synonymously labeled sets, involving 135 accessions were identified based on the
matching of multilocus SSR profiles. After the elimination of synonymous sets, the level of redundancy caused by closely related
accessions in the collection was assessed using a simulated sampling scheme that compared allelic diversity in different sample
sizes. The result of the simulation suggested that a random sample of 113 accessions could capture 90% of the total allelic
diversity in this collection. Principal Coordinate Analysis revealed that the Trinitario hybrids from Costa Rica shared a
high similarity among groups as well as among individual accessions. The analysis of the genetic structure illustrated that
the within-country/within-region difference accounted for 84.6% of the total molecular variation whereas the among-country/among-region
difference accounted for 15.4%. The Brazilian germplasm contributed most to this collection in terms of total alleles and
private alleles. The intercountry/interregion relationship by cluster analysis largely agreed with the geographical origin
of each germplasm group and supported the hypothesis that the Upper Amazon region is the center of diversity for cacao. The
results of the present study indicated that the CATIE International Cacao Collection contains a high level of genetic redundancy.
It should be possible to rationalize this collection by reducing redundancy and ensuring optimal representation of the genetic
diversity from distinct germplasm groups. The results also demonstrated that SSR markers, together with the statistical tools
for individual identification and redundancy assessment, are technically practical and sufficiently informative to assist
the management of a tropical plant germplasm collection. 相似文献
6.
Aliza A. Lindo Dwight E. Robinson Paula F. Tennant Lyndel W. Meinhardt Dapeng Zhang 《Tropical plant biology》2018,11(3-4):93-106
Cacao is an economically important commodity in Jamaica. Knowledge of the genetic diversity of Jamaican cacao germplasm is essential for their conservation and management. In spite of cacao’s economic importance in Jamaica, the crop is under studied, therefore limiting sound decisions toward improving productivity. Assessment of germplasm and on-farm genetic diversity is required to assist selecting superior genotypes to propagate and distribute across the island, as well as to use them as parental clones in breeding programs. Using 94 single nucleotide polymorphism (SNP) markers, 140 Jamaican cacao samples from two germplasm collections and a farmer’s estate along with 150 reference samples were analyzed. The principal coordinate analysis demonstrated that the majority of the Jamaican cacao selections were hybrids derived from five original germplasm groups, including Criollo, Amelonado and three Upper Amazon Forastero groups. Among the Upper Amazon groups, the Bayesian clustering analysis revealed that the Parinari (PA) ancestral lineage contributed the most (29.9%) to the Jamaican cacao germplasm. The germplasm collections showed greater diversity in terms of ancestral contributions compared to the farmer’s estate. However, the genetic differentiation between the three collecting sites was small (Fst?=?0.036), indicating that samples collected from the three sites were derived from a common pool of germplasm. The current study supports the historical records and clarified the ancestry of Jamaican cacao. Although the majority of the cacao genetic groups were observed in the Jamaican cacao collections, several diversity gaps were found in both germplasm collections and in the farmer’s estate, especially germplasm with disease resistance to cacao frosty pod rot that was recently found in Jamaica. 相似文献
7.
Criollo cacao (Theobroma cacao ssp. cacao) was cultivated by the Mayas over 1500 years ago. It has been suggested that Criollo cacao originated in Central America and that it evolved independently from the cacao populations in the Amazon basin. Cacao populations from the Amazon basin are included in the second morphogeographic group: Forastero, and assigned to T. cacao ssp. sphaerocarpum. To gain further insight into the origin and genetic basis of Criollo cacao from Central America, RFLP and microsatellite analyses were performed on a sample that avoided mixing pure Criollo individuals with individuals classified as Criollo but which might have been introgressed with Forastero genes. We distinguished these two types of individuals as Ancient and Modern Criollo. In contrast to previous studies, Ancient Criollo individuals formerly classified as 'wild', were found to form a closely related group together with Ancient Criollo individuals from South America. The Ancient Criollo trees were also closer to Colombian-Ecuadorian Forastero individuals than these Colombian-Ecuadorian trees were to other South American Forastero individuals. RFLP and microsatellite analyses revealed a high level of homozygosity and significantly low genetic diversity within the Ancient Criollo group. The results suggest that the Ancient Criollo individuals represent the original Criollo group. The results also implies that this group does not represent a separate subspecies and that it probably originated from a few individuals in South America that may have been spread by man within Central America. 相似文献
8.
Otocinclus cocama, a uniquely colored species of the loricariid catfish genus Otocinclus described solely from the type locality in the lower Ucayali River in northern Peru, is reported occurring in the Tigre River, a tributary to the Marañón River that drains a different section of the Andean Mountain range in the western Amazon. Both populations differ in the number of dark bars spanning the flanks of the body, and we investigated whether these morphotypes constitute distinct species. The body shapes of populations from the Tigre and Ucayali rivers were compared using geometric morphometrics. Although principal component analysis detected a broad overlap between populations, multivariate analysis of variance and linear driscriminat analysis revealed a subtle differentiation between the populations of the two hydrographic basins. Average body shape of the Ucayali River population tend to be slightly higher than that of the Tigre River, with the caudal peduncle stretched vertically in the Ucayali population. Multivariate regression of shape and centroid size revealed an allometric effect of 10.7% (p < 0.001), suggesting that the variation between Tigre and Ucayali populations was purely shape variation. Molecular data of coI, cytb, nd2, and 16S mitochondrial genes indicated a nucleotide diversity range from 0.001 to 0.003, and haplotypic diversity range from 0.600 ± 0.11 to 0.79 ± 0.07. The median-joining haplotype network for the concatenated matrix exhibited two divergent haplogroups related to the geographic area and separated by <10 mutational steps. The molecular species delimitation methods based on distance (automatic barcode gap discovery and assemble species by automatic partitioning) recovered two molecular lineages evolving independently, being one of the lineages formed by individuals from both populations. Tree-based methods (generalized mixed Yule coalescent and Bayesian implementation of the Poisson tree process) recovered similar topologies and supported single lineage recognition. Methods of molecular delimitation of species disclosed the high similarity between the two populations of Otocinclus cocama, further supported by the presence of old haplotypes common to both groups which could indicate that the populations still maintain gene flow. Although the morphological data reveal a subtle variation between both river basins, the molecular data suggest a weak population structuration based on hydrographic areas, but not different species lineages, therefore Otocinclus cocama is composed of a single lineage with two distinct morphotypes. 相似文献
9.
A new species of Anchoviella (Clupeiformes: Engraulidae) from the western Amazon River in Peru,with comments on congeners in the Peruvian Amazon River
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Anchoviella hernanni sp. nov. is described from the upper Amazon River basin, in tributaries of the Marañon, Ucayali and Madre de Dios river drainages that drain the Peruvian Andes. The new taxon can be distinguished from all congeners except Anchoviella jamesi, Anchoviella manamensis and Anchoviella perezi, by having 12–15 gill rakers in the lower branch of the first gill arch (v·16–35) and from those species by the distance between verticals through the posterior margin of the orbit to the posterior margin of the upper jaw 9·5–14·8% head length; LH (v. up to 6·0% LH). An updated identification key of all freshwater species of Anchoviella and morphological comparisons between all species of the genus occurring in Peru are provided. 相似文献
10.
Ives Bruno M. Efombagn Juan C. Motamayor Olivier Sounigo Albertus B. Eskes Salomon Nyassé Christian Cilas Ray Schnell Maria J. Manzanares-Dauleux Maria Kolesnikova-Allen 《Tree Genetics & Genomes》2008,4(4):821-831
The genetic diversity of 400 accessions collected in cacao farms, 95 GenBank, and 31 reference accessions was analyzed using
the 12 microsatellite markers. The GenBank and reference accessions were subdivided into 12 accession groups (AG) that belong
to the traditional cacao genetic groups (GG) Lower Amazon Forastero (LA), Upper Amazon Forastero (UA), Trinitario, and Criollo
(Cr). The 12-microsatellite loci revealed a total of 125 alleles, 113 of which were present in the farm accession group (FA).
The within and between group variation for all AGs accounted respectively for 81% and 19% of the total molecular variation.
The average F
is for the FA was 0.15 suggesting a moderate level of inbreeding. Significant differences for the level of gene diversity were
found between the farm (0.50), GenBank (0.42 to 0.62), and reference (0.10 to 0.60) AGs. Genetic differentiation among AGs
was variable with F
st values varying between 0.14 and 0.57 for the different AGs. Analysis using a Bayesian model-based method showed the existence
of a high level of admixture for the farm accessions group. The LA genes were most represented in the FA (54%), followed by
UA (33%) and Cr (7%). The genes of LA were also the most represented in the GenBank (48%), followed by UA (24%) and Cr (14%).
Only 14% and 6% of the genes of the GenBank and farm accessions, respectively, could not be attributed to any of the reference
GGs. The results suggest the predominating presence of LA genes in the Cameroon farm accessions and a high level of admixture,
with apparent presence of genes of more than three GGs in most accessions. The traditional Trinitario types appear to have
almost disappeared from farmers fields. The admixture must be the result of hybridization and recombination of these genes
from the different GGs in seed gardens and in farmers’ fields. The use of selected farm accessions will depend on the GG that
it belongs to and also on their level of heterozygosity. Further implications of the results for breeding and for introduction
of new germplasm into the Cameroon GenBank are discussed. 相似文献
11.
R. G. Loor A. M. Risterucci B. Courtois O. Fouet M. Jeanneau E. Rosenquist F. Amores A. Vasco M. Medina C. Lanaud 《Tree Genetics & Genomes》2009,5(3):421-433
The native Theobroma cacao L. population from Ecuador, known as Nacional, is famous for its fine cocoa flavour. From the beginning of the twentieth
century, however, it has been subjected to genetic erosion due principally to successive introductions of foreign germplasm
whose hybrid descendants gradually replaced the native plantations, implying a decrease in cocoa quality. We attempted to
trace this native cacao within a wide pool of modern Ecuadorian cacao population. Three hundred and twenty-two cacao accessions
collected from different geographical areas along the pacific coast of Ecuador and maintained in two living collections were
analysed using 40 simple-sequence repeat markers. Most of Ecuadorian cacao accessions displayed a high diversity and heterozygosity
level. A factorial analysis of correspondence (FAC) showed a continuous variation among them, with a few ones, grouped at
an extreme side of the FAC cloud, showing higher levels of homozygosity and lower introgression level by foreign cacaos. A
paternity analysis revealed that these highly homozygous individuals are the most probable ancestors of the modern Nacional
hybrid pool. These particular accessions studied could represent the native Nacional cacao present in Ecuador before the foreign
introductions. Their identification will help to conserve valuable genetic material and to improve cocoa quality in new cacao
varieties. 相似文献
12.
Identification of genetically diverse cacao with disease resistance, high productivity, and desirable organoleptic traits is vitally important to the agricultural crop’s long-term sustainability. Environmental changes, pests, and diseases as well as nation’s sovereign property rights have led to a decrease in accessibility and exchange of germplasm of interest. Having been introduced during colonial times, naturalized cacao in Puerto Rico could serve as an unexplored source of genetic diversity in improvement programs. An island-wide survey was carried out to identify naturalized trees and to determine their genetic associations to reference cacao accessions. Samples were genotyped with Expressed Sequence Tag-derived single nucleotide polymorphism (SNP) markers. Principal coordinate, cluster, and population structure analysis using the genotype data for both local and reference samples assigned individuals into five distinct genetic backgrounds: Criollo, Trinitario, Amelonado, Upper Amazon Forastero (UAF), and Nacional. Puerto Rican cacao fit into four (Criollo, Trinitario, Amelonado and UAF) of the five genetic backgrounds, being mainly composed of individuals of Criollo ancestry. Based on historical evidence, cacao of Criollo background was probably brought to Puerto Rico from Venezuela and/or Central America during colonial times. Trinitario, Amelonado, and UAF genetic backgrounds are most likely products of more modern introductions. Genotyping cacao in Puerto Rico provides information on the history and possible origin of the naturalized trees on the island. In addition, the assessment has allowed the targeting of material for incorporation and long-term conservation filling gaps in the existing collection and providing new germplasm to be evaluated for agronomic performance. 相似文献
13.
Maria L. Sereno Paulo S. B. Albuquerque Roland Vencovsky Antonio Figueira 《Conservation Genetics》2006,7(1):13-24
A sample of 94 accessions of Theobroma cacao L. (cacao), representing four populations from the Brazilian Amazon (Acre, Rondônia, lower Amazon and upper Amazon) were analyzed using microsatellite markers to assess the genetic diversity and the natural population structure. From the 19 microsatellite loci tested, 11 amplified scorable products, revealing a total of 49 alleles, including two monomorphic loci. The Brazilian upper Amazon population contained the largest genetic diversity, with the most polymorphic loci, the highest observed heterozygosity; and the majority of rare alleles, thereby this region might be considered part of the center of diversity of the species. The observed heterozygosity for all the Brazilian populations (H o = 0.347) was comparable with values reported for other similar upper Amazon Forastero cacao populations, with the Acre and Rondônia displaying the lowest values. The lower Amazon population, traditionally defined as highly homozygous, presented an unexpectedly high observed heterozygosity (H o = 0.372), disclosing rare and distinct alleles, with large identity with the upper Amazon population. It was hypothesized that part of the lower Amazon population might derive from successive natural or intentional introduction of planting material from other provenances, mainly upper Amazon. Most of the loci exhibited a lower observed heterozygosity than expected, suggesting that self-pollination might be more common than usually assumed in cacao, but excess of homozygotes might also derive from sub-grouping (Wahlund effect) or from sampling related individuals. Most of the gene diversity was found to occur within groups, with small differentiation between the four Brazilian Amazon populations, typical of species with high gene flow. 相似文献
14.
R. Whitkus M. de la Cruz L. Mota-Bravo A. Gómez-Pompa 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(5):621-627
Neotropical tree crops are affected by a combination of biological and human factors that complicate the study of genetic
diversity and crop evolution. Genetic diversity and relationships among southern Mexican populations and horticultural collections
of Theobroma cacao (chocolate, cocoa, cacao) are examined in light of the agricultural practices of the Maya. Collections of cacao were obtained
from the extremes of its geographic range including archeological sites in southern Mexico where cacao was first domesticated.
Genetic diversity was assayed by 57 informative random amplified polymorphic DNA (RAPD) marker loci. A unique sample of the
total diversity found in this study exists in the southern Mexican populations. These populations are significantly different
from all other cacao with regards to their profile of RAPD bands, including the ‘criollo’ variety, their morphological and
geographical group. A population of cacao found in a sinkhole (cenote) in northern Yucatan with genetic affinities to populations
in Chiapas suggests the Maya maintained plants far away from their native habitat. This finding concurs with known agroforestry
practices of the Maya. Modern efforts to increase germplasm of tropical tree crops such as cacao should carefully examine
archeological sites where genetic diversity, either deliberately or by chance, was collected and maintained by ancient cultures.
Received: 21 May 1997 / Accepted: 9 October 1997 相似文献
15.
Cuauhtemoc Cervantes-Martinez J. Steven Brown Raymond Schnell Juan C. Motamayor Alan W. Meerow Dapeng Zhang 《Tree Genetics & Genomes》2006,2(3):152-164
Current methods for measures of genetic diversity of populations and germplasm collections are often based on statistics calculated from molecular markers. The objective of this study was to investigate the precision and accuracy of the most common estimators of genetic variability and population structure, as calculated from simple sequence repeat (SSR) marker data from cacao (Theobroma cacao L.). Computer simulated genomes of replicate populations were generated from initial allele frequencies estimated using SSR data from cacao accessions in a collection. The simulated genomes consisted of ten linkage groups of 100 cM in length each. Heterozygosity, gene diversity and the F statistics were studied as a function of number of loci and trees sampled. The results showed that relatively small random samples of trees were needed to achieve consistency in the observed estimations. In contrast, very large random samples of loci per linkage group were required to enable reliable inferences on the whole genome. Precision of estimates was increased by more than 50% with an increase in sample size from one to five loci per linkage group or 50 per genome, and up to 70% with ten loci per linkage group, or equivalently, 100 loci per genome. The use of fewer, highly polymorphic loci to analyze genetic variability led to estimates with substantially smaller variance but with an upward bias. Nevertheless, the relative differences of estimates among populations were generally consistent for the different levels of polymorphism considered. 相似文献
16.
Dapeng Zhang Michel Boccara Lambert Motilal David R. Butler Pathmanathan Umaharan Sue Mischke Lyndel Meinhardt 《Conservation Genetics》2008,9(2):327-337
Utilization of germplasm for crop improvement is often hampered by absence of information regarding origin, genetic identity
and genealogical relationships of germplasm groups or populations. Molecular marker technology offers an efficient tool to
verify or reconstruct passport data. Using a high-throughput genotyping system with 15 microsatellite loci, we fingerprinted
482 accessions in 48 putative half-sib families of Refractario cacao (a group of germplasm collected from nine farms in Ecuador).
Based on the multilocus profiles, a Bayesian method for individual assignment was applied to verify membership in each half-sib
family. Multivariate statistical analysis showed that the Refractario genetic profile was different from other groups tested,
except for the “Nacional” cacao from the coastal valley of Ecuador. Hierarchical partitioning of genetic variance in the Refractario
cacao showed that 76% of the variation was contributed by intra-family difference, whereas the inter-family and inter-farm
difference accounted for 15 and 9% of total variance, respectively. All three sources of variation were highly significant
(P < 0.01). Cluster and Principal Coordinates Analyses revealed a population sub-structure in Refractario, which was also highly
heterozygous, suggesting hybridization derived from Nacional cacao and multiple other parental varieties, which all shared
a similar genetic background. The improved understanding of identities and structure in Refractario cacao will contribute
to more efficient conservation and use of this germplasm group in cacao breeding. 相似文献
17.
Sannohe Y Gomi S Murata T Ohyama M Yonekura K Kanegae M Koga J 《Bioscience, biotechnology, and biochemistry》2011,75(8):1606-1607
Cacao beans are composed of cacao nibs and germs. Although numerous chemical and physiological studies on cacao nib compounds have been reported, there is little information on cacao germ compounds. We therefore analyzed an extract from the cacao germ, and found two compounds that were specific to the germ. One of these two compounds was identified as the new glycosylated abscisic acid metabolite, dihydrophaseic acid-4'-O-6″-(β-ribofuranosyl)-β-glucopyranoside, and the other as the known compound, dihydrophaseic acid-4'-O-β-D-glucopyranoside. 相似文献
18.
Aikkal Riju M. K. Rajesh P. T. P. Fasila Sherin A. Chandrasekar S. Elain Apshara Vadivel Arunachalam 《Journal of genetics》2009,88(2):217-225
Expressed sequence tags (ESTs) provide researchers with a quick and inexpensive route for discovering new genes, data on gene
expression and regulation, and also provide genic markers that help in constructing genome maps. Cacao is an important perennial
crop of humid tropics. Cacao EST sequences, as available in the public domain, were downloaded and made into contigs. Microsatellites
were located in these ESTs and contigs using five softwares (MISA, TRA, TROLL, SSRIT and SSR primer). MISA gave maximum coverage
of SSRs in cacao ESTs and contigs, although TRA was able to detect higher order (>5-mer) repeats. The frequency of SSRs was
one per 26.9 kb in the known set of ESTs. One-third of the repeats in EST-contigs were found to be trimeric. A few rare repeats
like 21-mer repeat were also located. A/T repeats were most abundant among the mononucleotide repeats and the AG/GA/TC/CT
type was the most frequent among dimerics. Flanking primers were designed using Primer3 program and verified experimentally
for PCR amplification. The results of the study are made available freely online database (). Seven primer pairs amplified genomic DNA isolated from leaves were used to screen a representative set of 12 accessions
of cacao. 相似文献
19.
Elisa S. L. Santos Carlos Bernard M. Cerqueira-Silva Gustavo M. Mori Dário Ahnert Durval L. N. Mello José Luis Pires Ronan X. Corrêa Anete P. de Souza 《PloS one》2015,10(12)
Bahia is the most important cacao-producing state in Brazil, which is currently the sixth-largest country worldwide to produce cacao seeds. In the eighteenth century, the Comum, Pará and Maranhão varieties of cacao were introduced into southern Bahia, and their descendants, which are called ‘Bahian cacao’ or local Bahian varieties, have been cultivated for over 200 years. Comum plants have been used to start plantations in African countries and extended as far as countries in South Asia and Oceania. In Brazil, two sets of clones selected from Bahian varieties and their mutants, the Agronomic Institute of East (SIAL) and Bahian Cacao Institute (SIC) series, represent the diversity of Bahian cacao in germplasm banks. Because the genetic diversity of Bahian varieties, which is essential for breeding programs, remains unknown, the objective of this work was to assess the genetic structure and diversity of local Bahian varieties collected from farms and germplasm banks. To this end, 30 simple sequence repeat (SSR) markers were used to genotype 279 cacao plants from germplasm and local farms. The results facilitated the identification of 219 cacao plants of Bahian origin, and 51 of these were SIAL or SIC clones. Bahian cacao showed low genetic diversity. It could be verified that SIC and SIAL clones do not represent the true diversity of Bahian cacao, with the greatest amount of diversity found in cacao trees on the farms. Thus, a core collection to aid in prioritizing the plants to be sampled for Bahian cacao diversity is suggested. These results provide information that can be used to conserve Bahian cacao plants and applied in breeding programs to obtain more productive Bahian cacao with superior quality and tolerance to major diseases in tropical cacao plantations worldwide. 相似文献