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1.
Nat Genet ; 56(4): 721-731, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38622339

ABSTRACT

Coffea arabica, an allotetraploid hybrid of Coffea eugenioides and Coffea canephora, is the source of approximately 60% of coffee products worldwide, and its cultivated accessions have undergone several population bottlenecks. We present chromosome-level assemblies of a di-haploid C. arabica accession and modern representatives of its diploid progenitors, C. eugenioides and C. canephora. The three species exhibit largely conserved genome structures between diploid parents and descendant subgenomes, with no obvious global subgenome dominance. We find evidence for a founding polyploidy event 350,000-610,000 years ago, followed by several pre-domestication bottlenecks, resulting in narrow genetic variation. A split between wild accessions and cultivar progenitors occurred ~30.5 thousand years ago, followed by a period of migration between the two populations. Analysis of modern varieties, including lines historically introgressed with C. canephora, highlights their breeding histories and loci that may contribute to pathogen resistance, laying the groundwork for future genomics-based breeding of C. arabica.


Subject(s)
Coffea , Coffea/genetics , Coffee , Genome, Plant/genetics , Metagenomics , Plant Breeding
2.
PLoS One ; 19(1): e0296362, 2024.
Article in English | MEDLINE | ID: mdl-38206909

ABSTRACT

The wild species of the Coffea genus present a very wide morphological, genetic, and biochemical diversity. Wild species are recognized more resistant to diseases, pests, and environmental variations than the two species currently cultivated worldwide: C. arabica (Arabica) and C. canephora (Robusta). Consequently, wild species are now considered as a crucial resource for adapting cultivated coffee trees to climate change. Within the Coffea genus, 79 wild species are native to the Indian Ocean islands of Comoros, Mayotte, Mauritius, Réunion and Madagascar, out of a total of 141 taxa worldwide. Among them, a group of 9 species called "Baracoffea" are particularly atypical in their morphology and adaptation to the sandy soils of the dry deciduous forests of western Madagascar. Here, we have attempted to shed light on the evolutionary history of three Baracoffea species: C. ambongensis, C. boinensis and C. bissetiae by analyzing their chloroplast and nuclear genomes. We assembled the complete chloroplast genomes de novo and extracted 28,800 SNP (Single Nucleotide Polymorphism) markers from the nuclear genomes. These data were used for phylogenetic analysis of Baracoffea with Coffea species from Madagascar and Africa. Our new data support the monophyletic origin of Baracoffea within the Coffea of Madagascar, but also reveal a divergence with a sister clade of four species: C. augagneurii, C. ratsimamangae, C. pervilleana and C. Mcphersonii (also called C. vohemarensis), belonging to the Subterminal botanical series and living in dry or humid forests of northern Madagascar. Based on a bioclimatic analysis, our work suggests that Baracoffea may have diverged from a group of Malagasy Coffea from northern Madagascar and adapted to the specific dry climate and low rainfall of western Madagascar. The genomic data generated in the course of this work will contribute to the understanding of the adaptation mechanisms of these particularly singular species.


Subject(s)
Biological Evolution , Coffea , Phylogeny , Madagascar , Indian Ocean Islands , Chloroplasts , Coffea/genetics
3.
PeerJ ; 11: e15778, 2023.
Article in English | MEDLINE | ID: mdl-37554339

ABSTRACT

Background: Leaf symbiosis is a phenomenon in which host plants of Rubiaceae interact with bacterial endophytes within their leaves. To date, it has been found in around 650 species belonging to eight genera in four tribes; however, the true extent in Rubiaceae remains unknown. Our aim is to investigate the possible occurrence of leaf endophytes in the African plant genera Empogona and Tricalysia and, if present, to establish their identity. Methods: Total DNA was extracted from the leaves of four species of the Coffeeae tribe (Empogona congesta, Tricalysia hensii, T. lasiodelphys, and T. semidecidua) and sequenced. Bacterial reads were filtered out and assembled. Phylogenetic analysis of the endophytes was used to reveal their identity and their relationship with known symbionts. Results: All four species have non-nodulated leaf endophytes, which are identified as Caballeronia. The endophytes are distinct from each other but related to other nodulated and non-nodulated endophytes. An apparent phylogenetic or geographic pattern appears to be absent in endophytes or host plants. Caballeronia endophytes are present in the leaves of Empogona and Tricalysia, two genera not previously implicated in leaf symbiosis. This interaction is likely to be more widespread, and future discoveries are inevitable.


Subject(s)
Burkholderia , Burkholderiaceae , Rubiaceae , Endophytes/genetics , Rubiaceae/genetics , Phylogeny , Metagenomics , Plants , Plant Leaves/microbiology
5.
Sci Rep ; 11(1): 8119, 2021 04 14.
Article in English | MEDLINE | ID: mdl-33854089

ABSTRACT

Caffeine is the most consumed alkaloid stimulant in the world. It is synthesized through the activity of three known N-methyltransferase proteins. Here we are reporting on the 422-Mb chromosome-level assembly of the Coffea humblotiana genome, a wild and endangered, naturally caffeine-free, species from the Comoro archipelago. We predicted 32,874 genes and anchored 88.7% of the sequence onto the 11 chromosomes. Comparative analyses with the African Robusta coffee genome (C. canephora) revealed an extensive genome conservation, despite an estimated 11 million years of divergence and a broad diversity of genome sizes within the Coffea genus. In this genome, the absence of caffeine is likely due to the absence of the caffeine synthase gene which converts theobromine into caffeine through an illegitimate recombination mechanism. These findings pave the way for further characterization of caffeine-free species in the Coffea genus and will guide research towards naturally-decaffeinated coffee drinks for consumers.


Subject(s)
Coffea/genetics , Methyltransferases/genetics , Plant Proteins/genetics , Amino Acid Sequence , Caffeine/analysis , Chromosomes, Plant , Coffea/chemistry , Coffea/enzymology , Comoros , Comparative Genomic Hybridization , Evolution, Molecular , Methyltransferases/classification , Methyltransferases/deficiency , Phylogeny , Plant Leaves/chemistry , Plant Leaves/enzymology , Plant Leaves/genetics , Plant Proteins/classification , Plant Proteins/metabolism , Sequence Alignment , Sequence Analysis, RNA , Theobromine/analysis
6.
Database (Oxford) ; 20202020 11 20.
Article in English | MEDLINE | ID: mdl-33216899

ABSTRACT

Coffee is a beverage enjoyed by millions of people worldwide and an important commodity for millions of people. Beside the two cultivated species (Coffea arabica and Coffea canephora), the 139 wild coffee species/taxa belonging to the Coffea genus are largely unknown to coffee scientists and breeders although these species may be crucial for future coffee crop development to face climate changes. Here we present the Wild Coffee Species database (WCSdb) hosted by Pl@ntNet platform (http://publish.plantnet-project.org/project/wildcofdb_en), providing information for 141 coffee species/taxa, for which 84 contain a photo gallery and 82 contain sequencing data (genotyping-by-sequencing, chloroplast or whole genome sequences). The objective of this database is to better understand and characterize the species (identification, morphology, biochemical compounds, genetic diversity and sequence data) in order to better protect and promote them. DATABASE URL: http://publish.plantnet-project.org/project/wildcofdb_en.


Subject(s)
Coffea , Coffea/genetics , Coffee , Humans , Sequence Analysis
7.
Mol Phylogenet Evol ; 151: 106906, 2020 10.
Article in English | MEDLINE | ID: mdl-32653553

ABSTRACT

For decades coffees were associated with the genus Coffea. In 2011, the closely related genus Psilanthus was subsumed into Coffea. However, results obtained in 2017-based on 28,800 nuclear SNPs-indicated that there is not substantial phylogenetic support for this incorporation. In addition, a recent study of 16 plastid full-genome sequences highlighted an incongruous placement of Coffea canephora (Robusta coffee) between maternal and nuclear trees. In this study, similar global features of the plastid genomes of Psilanthus and Coffea are observed. In agreement with morphological and physiological traits, the nuclear phylogenetic tree clearly separates Psilanthus from Coffea (with exception to C. rhamnifolia, closer to Psilanthus than to Coffea). In contrast, the maternal molecular tree was incongruent with both morphological and nuclear differentiation, with four main clades observed, two of which include both Psilanthus and Coffea species, and two with either Psilanthus or Coffea species. Interestingly, Coffea and Psilanthus taxa sampled in West and Central Africa are members of the same group. Several mechanisms such as the retention of ancestral polymorphisms due to incomplete lineage sorting, hybridization leading to homoploidy (without chromosome doubling) and alloploidy (for C. arabica) are involved in the evolutionary history of the coffee species. While sharing similar morphological characteristics, the genetic relationships within C. canephora have shown that some populations are well differentiated and genetically isolated. Given the position of its closely-related species, we may also consider C. canephora to be undergoing a long process of speciation with an intermediate step of (sub-)speciation.


Subject(s)
Cell Nucleus/genetics , Coffea/genetics , Evolution, Molecular , Genome, Plastid , Polymorphism, Single Nucleotide/genetics , Cluster Analysis , Phylogeny , Species Specificity
8.
PLoS One ; 15(4): e0232295, 2020.
Article in English | MEDLINE | ID: mdl-32353023

ABSTRACT

In Rubiaceae phylogenetics, the number of markers often proved a limitation with authors failing to provide well-supported trees at tribal and generic levels. A robust phylogeny is a prerequisite to study the evolutionary patterns of traits at different taxonomic levels. Advances in next-generation sequencing technologies have revolutionized biology by providing, at reduced cost, huge amounts of data for an increased number of species. Due to their highly conserved structure, generally recombination-free, and mostly uniparental inheritance, chloroplast DNA sequences have long been used as choice markers for plant phylogeny reconstruction. The main objectives of this study are: 1) to gain insight in chloroplast genome evolution in the Rubiaceae (Ixoroideae) through efficient methodology for de novo assembly of plastid genomes; and, 2) to test the efficiency of mining SNPs in the nuclear genome of Ixoroideae based on the use of a coffee reference genome to produce well-supported nuclear trees. We assembled whole chloroplast genome sequences for 27 species of the Rubiaceae subfamily Ixoroideae using next-generation sequences. Analysis of the plastid genome structure reveals a relatively good conservation of gene content and order. Generally, low variation was observed between taxa in the boundary regions with the exception of the inverted repeat at both the large and short single copy junctions for some taxa. An average of 79% of the SNP determined in the Coffea genus are transferable to Ixoroideae, with variation ranging from 35% to 96%. In general, the plastid and the nuclear genome phylogenies are congruent with each other. They are well-resolved with well-supported branches. Generally, the tribes form well-identified clades but the tribe Sherbournieae is shown to be polyphyletic. The results are discussed relative to the methodology used and the chloroplast genome features in Rubiaceae and compared to previous Rubiaceae phylogenies.


Subject(s)
Chloroplasts/genetics , DNA, Chloroplast/genetics , Genome, Chloroplast/genetics , Genome, Plant/genetics , Rubiaceae/genetics , Coffea/genetics , Evolution, Molecular , Genomics/methods , High-Throughput Nucleotide Sequencing/methods , Phylogeny , Polymorphism, Single Nucleotide/genetics , Sequence Analysis, DNA/methods
9.
Ann Bot ; 126(5): 849-863, 2020 10 06.
Article in English | MEDLINE | ID: mdl-32303759

ABSTRACT

BACKGROUND AND AIMS: Like other clades, the Coffea genus is highly diversified on the island of Madagascar. The 66 endemic species have colonized various environments and consequently exhibit a wide diversity of morphological, functional and phenological features and reproductive strategies. The trends of interspecific trait variation, which stems from interactions between genetically defined species and their environment, still needed to be addressed for Malagasy coffee trees. METHODS: Data acquisition was done in the most comprehensive ex situ collection of Madagascan wild Coffea. The structure of endemic wild coffees maintained in an ex situ collection was explored in terms of morphological, phenological and functional traits. The environmental (natural habitat) effect was assessed on traits in species from distinct natural habitats. Phylogenetic signal (Pagel's λ, Blomberg's K) was used to quantify trait proximities among species according to their phylogenetic relatedness. KEY RESULTS: Despite the lack of environmental difference in the ex situ collection, widely diverging phenotypes were observed. Phylogenetic signal was found to vary greatly across and even within trait categories. The highest values were exhibited by the ratio of internode mass to leaf mass, the length of the maturation phase and leaf dry matter content (ratio of dry leaf mass to fresh leaf mass). By contrast, traits weakly linked to phylogeny were either constrained by the original natural environment (leaf size) or under selective pressures (phenological traits). CONCLUSIONS: This study gives insight into complex patterns of trait variability found in an ex situ collection, and underlines the opportunities offered by living ex situ collections for research characterizing phenotypic variation.


Subject(s)
Coffee , Plant Leaves , Islands , Madagascar , Phenotype , Phylogeny
10.
PLoS One ; 14(6): e0216347, 2019.
Article in English | MEDLINE | ID: mdl-31188829

ABSTRACT

Chloroplast sequences are widely used for phylogenetic analysis due to their high degree of conservation in plants. Whole chloroplast genomes can now be readily obtained for plant species using new sequencing methods, giving invaluable data for plant evolution However new annotation methods are required for the efficient analysis of this data to deliver high quality phylogenetic analyses. In this study, the two main tools for chloroplast genome annotation were compared. More consistent detection and annotation of genes were produced with GeSeq when compared to the currently used Dogma. This suggests that the annotation of most of the previously annotated chloroplast genomes should now be updated. GeSeq was applied to species related to coffee, including 16 species of the Coffea and Psilanthus genera to reconstruct the ancestral chloroplast genomes and to evaluate their phylogenetic relationships. Eight genes in the plant chloroplast pan genome (consisting of 92 genes) were always absent in the coffee species analyzed. Notably, the two main cultivated coffee species (i.e. Arabica and Robusta) did not group into the same clade and differ in their pattern of gene evolution. While Arabica coffee (Coffea arabica) belongs to the Coffea genus, Robusta coffee (Coffea canephora) is associated with the Psilanthus genus. A more extensive survey of related species is required to determine if this is a unique attribute of Robusta coffee or a more widespread feature of coffee tree species.


Subject(s)
Coffee/genetics , Genome, Chloroplast/genetics , Molecular Sequence Annotation/methods , Phylogeny , Evolution, Molecular , Genes, Plant , Molecular Sequence Annotation/standards , Sequence Analysis, DNA
11.
PhytoKeys ; (83): 103-118, 2017.
Article in English | MEDLINE | ID: mdl-29033652

ABSTRACT

Craterispermum capitatum and C. gabonicum, two new species of Rubiaceae, are described from the Lower Guinea and Congolian Domains. Detailed descriptions and distribution maps are provided for each species, their conservation status is assessed and their taxonomic affinities are discussed. Craterispermum gabonicum is unique within the genus because of the strong dimorphism in brevistylous and longistylous flowers and inflorescences. We hypothesize that this species shows some form of dioecy. The distribution of C. capitatum shows a wide disjunction: the species is present in the Lower Guinean and Congolian Domains but absent from Gabon and South Cameroon. An identification key for the Craterispermum species present in the Lower Guinean and Congolian Domains is given.


Résumé Craterispermum capitatum et C. gabonicum, deux nouvelles espèces de la famille des Rubiaceae, des Domaines Bas Guinéen et Congolais sont décrites. Des descriptions détaillées et des cartes de distribution sont données pour chacune des espèces, leur statut de conservation est évalué et leurs affinités taxonomiques discutée. Craterispermum gabonicum est unique dans le genre en raison d'un dimorphisme avéré entre les fleurs, mais aussi les inflorescences brévistyles et longistyles. L'hypothèse de l'existence d'une tendance vers la dioécie chez cette espèce est émise. La distribution C. capitatum présente une importante disjonction: l'espèce est présente dans les Domaines Bas Guinéen et Congolais, mais absente au Gabon et au sud du Cameroun. Une clé d'identification pour les espèces de Craterispermum présentes dans les Domaines Bas Guinéen et Congolais est donnée.

12.
Mol Genet Genomics ; 292(4): 741-754, 2017 Aug.
Article in English | MEDLINE | ID: mdl-28314936

ABSTRACT

Coffea arabica (the Arabica coffee) is an allotetraploid species originating from a recent hybridization between two diploid species: C. canephora and C. eugenioides. Transposable elements can drive structural and functional variation during the process of hybridization and allopolyploid formation in plants. To learn more about the evolution of the C. arabica genome, we characterized and studied a new Copia LTR-Retrotransposon (LTR-RT) family in diploid and allotetraploid Coffea genomes called Divo. It is a complete and relatively compact LTR-RT element (~5 kb), carrying typical Gag and Pol Copia type domains. Reverse Trancriptase (RT) domain-based phylogeny demonstrated that Divo is a new and well-supported family in the Bianca lineage, but strictly restricted to dicotyledonous species. In C. canephora, Divo is expressed and showed a genomic distribution along gene rich and gene poor regions. The copy number, the molecular estimation of insertion time and the analysis at orthologous locations of insertions in diploid and allotetraploid coffee genomes suggest that Divo underwent a different and recent transposition activity in C. arabica and C. canephora when compared to C. eugenioides. The analysis of this novel LTR-RT family represents an important step toward uncovering the genome structure and evolution of C. arabica allotetraploid genome.


Subject(s)
Coffea/genetics , DNA, Plant/genetics , Genome, Plant/genetics , Retroelements/genetics , Terminal Repeat Sequences/genetics , Base Sequence , Gene Dosage/genetics , Sequence Analysis, DNA , Tetraploidy
13.
Mol Phylogenet Evol ; 109: 351-361, 2017 04.
Article in English | MEDLINE | ID: mdl-28212875

ABSTRACT

A comprehensive and meaningful phylogenetic hypothesis for the commercially important coffee genus (Coffea) has long been a key objective for coffee researchers. For molecular studies, progress has been limited by low levels of sequence divergence, leading to insufficient topological resolution and statistical support in phylogenetic trees, particularly for the major lineages and for the numerous species occurring in Madagascar. We report here the first almost fully resolved, broadly sampled phylogenetic hypothesis for coffee, the result of combining genotyping-by-sequencing (GBS) technology with a newly developed, lab-based workflow to integrate short read next-generation sequencing for low numbers of additional samples. Biogeographic patterns indicate either Africa or Asia (or possibly the Arabian Peninsula) as the most likely ancestral locality for the origin of the coffee genus, with independent radiations across Africa, Asia, and the Western Indian Ocean Islands (including Madagascar and Mauritius). The evolution of caffeine, an important trait for commerce and society, was evaluated in light of our phylogeny. High and consistent caffeine content is found only in species from the equatorial, fully humid environments of West and Central Africa, possibly as an adaptive response to increased levels of pest predation. Moderate caffeine production, however, evolved at least one additional time recently (between 2 and 4Mya) in a Madagascan lineage, which suggests that either the biosynthetic pathway was already in place during the early evolutionary history of coffee, or that caffeine synthesis within the genus is subject to convergent evolution, as is also the case for caffeine synthesis in coffee versus tea and chocolate.


Subject(s)
Biological Evolution , Caffeine/analysis , Coffea/chemistry , Coffea/genetics , Africa , Asia , Coffea/classification , DNA, Plant , Genotype , Phylogeny , Phylogeography , Sequence Analysis, DNA
14.
Mol Genet Genomics ; 291(5): 1979-90, 2016 Oct.
Article in English | MEDLINE | ID: mdl-27469896

ABSTRACT

The Coffea genus, 124 described species, has a natural distribution spreading from inter-tropical Africa, to Western Indian Ocean Islands, India, Asia and up to Australasia. Two cultivated species, C. arabica and C. canephora, are intensively studied while, the breeding potential and the genome composition of all the wild species remained poorly uncharacterized. Here, we report the characterization and comparison of the highly repeated transposable elements content of 11 Coffea species representatives of the natural biogeographic distribution. A total of 994 Mb from 454 reads were produced with a genome coverage ranging between 3.2 and 15.7 %. The analyses showed that highly repeated transposable elements, mainly LTR retrotransposons (LTR-RT), represent between 32 and 53 % of Coffea genomes depending on their biogeographic location and genome size. Species from West and Central Africa (Eucoffea) contained the highest LTR-RT content but with no strong variation relative to their genome size. At the opposite, for the insular species (Mascarocoffea), a strong variation of LTR-RT was observed suggesting differential dynamics of these elements in this group. Two LTR-RT lineages, SIRE and Del were clearly differentially accumulated between African and insular species, suggesting these lineages were associated to the genome divergence of Coffea species in Africa. Altogether, the information obtained in this study improves our knowledge and brings new data on the composition, the evolution and the divergence of wild Coffea genomes.


Subject(s)
Coffea/genetics , Retroelements , Sequence Analysis, DNA/methods , Coffea/classification , Evolution, Molecular , Genetic Variation , Genome Size , Genome, Plant , Phylogeography
15.
Ecol Evol ; 6(10): 3240-55, 2016 May.
Article in English | MEDLINE | ID: mdl-27096083

ABSTRACT

The frequency of plant species introductions has increased in a highly connected world, modifying species distribution patterns to include areas outside their natural ranges. These introductions provide the opportunity to gain new insight into the importance of flowering phenology as a component of adaptation to a new environment. Three Coffea species, C. arabica, C. canephora (Robusta), and C. liberica, native to intertropical Africa have been introduced to New Caledonia. On this archipelago, a secondary contact zone has been characterized where these species coexist, persist, and hybridize spontaneously. We investigated the impact of environmental changes undergone by each species following its introduction in New Caledonia on flowering phenology and overcoming reproductive barriers between sister species. We developed species distribution models and compared both environmental envelopes and climatic niches between native and introduced hybrid zones. Flowering phenology was monitored in a population in the hybrid zone along with temperature and precipitation sequences recorded at a nearby weather station. The extent and nature of hybridization events were characterized using chloroplast and nuclear microsatellite markers. The three Coffea species encountered weak environmental suitability compared to their native ranges when introduced to New Caledonia, especially C. arabica and C. canephora. The niche of the New Caledonia hybrid zone was significantly different from all three species' native niches based on identity tests (I Similarity and D Schoener's Similarity Indexes). This area appeared to exhibit intermediate conditions between the native conditions of the three species for temperature-related variables and divergent conditions for precipitation-related ones. Flowering pattern in these Coffea species was shown to have a strong genetic component that determined the time between the triggering rain and anthesis (flower opening), specific to each species. However, a precipitation regime different from those in Africa was directly involved in generating partial flowering overlap between species and thus in allowing hybridization and interspecific gene flow. Interspecific hybrids accounted for 4% of the mature individuals in the sympatric population and occurred between each pair of species with various level of introgression. Adaptation to new environmental conditions following introduction of Coffea species to New Caledonia has resulted in a secondary contact between three related species, which would not have happened in their native ranges, leading to hybridization and gene flow.

16.
Mol Genet Genomics ; 291(1): 155-68, 2016 Feb.
Article in English | MEDLINE | ID: mdl-26231981

ABSTRACT

The completion of the genome assembly for the economically important coffee plant Coffea canephora (Rubiaceae) has allowed the use of bioinformatic tools to identify and characterize a diverse array of transposable elements (TEs), which can be used in evolutionary studies of the genus. An overview of the copy number and location within the C. canephora genome of four TEs is presented. These are tested for their use as molecular markers to unravel the evolutionary history of the Millotii Complex, a group of six wild coffee (Coffea) species native to Madagascar. Two TEs from the Gypsy superfamily successfully recovered some species boundaries and geographic structure among samples, whereas a TE from the Copia superfamily did not. Notably, species occurring in evergreen moist forests of eastern and southeastern Madagascar were divergent with respect to species in other habitats and regions. Our results suggest that the peak of transpositional activity of the Gypsy and Copia TEs occurred, respectively, before and after the speciation events of the tested Madagascan species. We conclude that the utilization of active TEs has considerable potential to unravel the evolutionary history and delimitation of closely related Coffea species. However, the selection of TE needs to be experimentally tested, since each element has its own evolutionary history. Different TEs with similar copy number in a given species can render different dendrograms; thus copy number is not a good selection criterion to attain phylogenetic resolution.


Subject(s)
Coffea/genetics , Coffee/genetics , DNA Transposable Elements/genetics , Genome, Plant/genetics , DNA, Plant/genetics , Evolution, Molecular , Gene Dosage/genetics , Phylogeny
17.
Plant Mol Biol ; 89(1-2): 83-97, 2015 Sep.
Article in English | MEDLINE | ID: mdl-26245353

ABSTRACT

Retrotransposons are the main component of plant genomes. Recent studies have revealed the complexity of their evolutionary dynamics. Here, we have identified Copia25 in Coffea canephora, a new plant retrotransposon belonging to the Ty1-Copia superfamily. In the Coffea genomes analyzed, Copia25 is present in relatively low copy numbers and transcribed. Similarity sequence searches and PCR analyses show that this retrotransposon with LTRs (Long Terminal Repeats) is widely distributed among the Rubiaceae family and that it is also present in other distantly related species belonging to Asterids, Rosids and monocots. A particular situation is the high sequence identity found between the Copia25 sequences of Musa, a monocot, and Ixora, a dicot species (Rubiaceae). Our results reveal the complexity of the evolutionary dynamics of the ancient element Copia25 in angiosperm, involving several processes including sequence conservation, rapid turnover, stochastic losses and horizontal transfer.


Subject(s)
Magnoliopsida/genetics , Retroelements/genetics , Coffea/genetics , Evolution, Molecular , Gene Dosage/genetics , Genes, Plant/genetics , Genome, Plant/genetics , Molecular Sequence Data , Musa/genetics , Phylogeny , Polymerase Chain Reaction , Rubiaceae/genetics , Sequence Analysis, DNA , Terminal Repeat Sequences/genetics
18.
Genome Biol Evol ; 7(2): 493-504, 2015 Jan 07.
Article in English | MEDLINE | ID: mdl-25573958

ABSTRACT

A novel structure of nonautonomous long terminal repeat (LTR) retrotransposons called terminal repeat with GAG domain (TR-GAG) has been described in plants, both in monocotyledonous, dicotyledonous and basal angiosperm genomes. TR-GAGs are relatively short elements in length (<4 kb) showing the typical features of LTR-retrotransposons. However, they carry only one open reading frame coding for the GAG precursor protein involved for instance in transposition, the assembly, and the packaging of the element into the virus-like particle. GAG precursors show similarities with both Copia and Gypsy GAG proteins, suggesting evolutionary relationships of TR-GAG elements with both families. Despite the lack of the enzymatic machinery required for their mobility, strong evidences suggest that TR-GAGs are still active. TR-GAGs represent ubiquitous nonautonomous structures that could be involved in the molecular diversities of plant genomes.


Subject(s)
Coffea/genetics , Genome, Plant , Retroelements/genetics , Terminal Repeat Sequences/genetics , Algorithms , Base Sequence , Conserved Sequence/genetics , Gene Dosage , Markov Chains , Molecular Sequence Annotation , Molecular Sequence Data , Multigene Family , Transcription, Genetic
19.
Ann Bot ; 111(2): 229-48, 2013 Feb.
Article in English | MEDLINE | ID: mdl-23275631

ABSTRACT

BACKGROUND AND AIMS: The coffee genus (Coffea) comprises 124 species, and is indigenous to the Old World Tropics. Due to its immense economic importance, Coffea has been the focus of numerous genetic diversity studies, but despite this effort it remains insufficiently studied. In this study the genetic diversity and genetic structure of Coffea across Africa and the Indian Ocean islands is investigated. METHODS: Genetic data were produced using 13 polymorphic nuclear microsatellite markers (simple sequence repeats, SSRs), including seven expressed sequence tag-SSRs, and the data were analysed using model- and non-model-based methods. The study includes a total of 728 individuals from 60 species. KEY RESULTS: Across Africa and the Indian Ocean islands Coffea comprises a closely related group of species with an overall pattern of genotypes running from west to east. Genetic structure was identified in accordance with pre-determined geographical regions and phylogenetic groups. There is a good relationship between morpho-taxonomic species delimitations and genetic units. Genetic diversity in African and Indian Ocean Coffea is high in terms of number of alleles detected, and Madagascar appears to represent a place of significant diversification in terms of allelic richness and species diversity. CONCLUSIONS: Cross-species SSR transferability in African and Indian Ocean islands Coffea was very efficient. On the basis of the number of private alleles, diversification in East Africa and the Indian Ocean islands appears to be more recent than in West and West-Central Africa, although this general trend is complicated in Africa by the position of species belonging to lineages connecting the main geographical regions. The general pattern of phylogeography is not in agreement with an overall east to west (Mascarene, Madagascar, East Africa, West Africa) increase in genome size, the high proportion of shared alleles between the four regions or the high numbers of exclusive shared alleles between pairs or triplets of regions.


Subject(s)
Coffea/genetics , Genetic Variation , Microsatellite Repeats/genetics , Africa , Alleles , Genetic Structures , Genetics, Population , Genotype , Geography , Indian Ocean Islands , Phylogeny
20.
Am J Bot ; 99(10): e411-4, 2012 Oct.
Article in English | MEDLINE | ID: mdl-23028001

ABSTRACT

PREMISE OF THE STUDY: Informative markers are required for assessing the diversity of Amborella trichopoda, the only species of its order, endemic to New Caledonia and considered to be the sister species to all flowering plants. Therefore, expressed sequence tag (EST)-based microsatellite markers were developed. • METHODS AND RESULTS: Fifty-five microsatellite loci were characterized in 14896 putative unigenes, which were generated by assembling A. trichopoda ESTs from the public sequence database. Seventeen markers revealed polymorphism in 80 adult shrubs from three populations. The number of alleles per locus ranged from two to 12, with a total of 132 alleles scored. The mean expected heterozygosity per population ranged from 0.336 to 0.567. • CONCLUSIONS: These markers offer an appropriate amount of variation to investigate genetic diversity structure, gene flow, and other conservation issues.


Subject(s)
Magnoliopsida/genetics , Microsatellite Repeats/genetics , DNA, Plant/genetics , DNA, Plant/isolation & purification , Genetic Loci/genetics , New Caledonia , Polymorphism, Genetic
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