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Genetic differentiation and hybrid identification using microsatellite markers in closely related wild species.

ABSTRACT: Identifying the genetic basis of speciation is critical for understanding the evolutionary history of closely related wild species. Recently diverged species facilitate the study of speciation because many genetic and morphological characteristics are still shared by the organisms under study. The Petunia genus grows in South American grasslands and comprises both recently diverged wild species and commercial species. In this work, we analysed two closely related species: Petunia exserta, which has a narrow endemic range and grows exclusively in rocky shelters, and Petunia axillaris, which is widely distributed and comprises three allopatric subspecies. Petunia axillaris ssp. axillaris and P. exserta occur in sympatry, and putative hybrids between them have been identified. Here, we analysed 14 expressed sequence tag-simple sequence repeats (EST-SSRs) in 126 wild individuals and 13 putative morphological hybrids with the goals of identifying differentially encoded alleles to characterize their natural genetic diversity, establishing a genetic profile for each taxon and to verify the presence of hybridization signal. Overall, 143 alleles were identified and all taxa contained private alleles. Four major groups were identified in clustering analyses, which indicated that there are genetic distinctions among the groups. The markers evaluated here will be useful in evolutionary studies involving these species and may help categorize individuals by species, thus enabling the identification of hybrids between both their putative taxa. The individuals with intermediate morphology presented private alleles of their both putative parental species, although they showed a level of genetic mixing that was comparable with some of the individuals with typical P. exserta morphology. The EST-SSR markers scattered throughout the Petunia genome are very efficient tools for characterizing the genetic diversity in wild taxa of this genus and aid in identifying interspecific hybrids based on the presence of private alleles. These properties indicate that these markers will be helpful tools in evolutionary studies.

SUBMITTER: Turchetto C

PROVIDER: S-EPMC4565426 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

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Genetic differentiation and hybrid identification using microsatellite markers in closely related wild species.

Turchetto Caroline C Segatto Ana Lúcia A AL Beduschi Júlia J Bonatto Sandro L SL Freitas Loreta B LB

AoB PLANTS 20150717

Identifying the genetic basis of speciation is critical for understanding the evolutionary history of closely related wild species. Recently diverged species facilitate the study of speciation because many genetic and morphological characteristics are still shared by the organisms under study. The Petunia genus grows in South American grasslands and comprises both recently diverged wild species and commercial species. In this work, we analysed two closely related species: Petunia exserta, which ...[more]

PMID: 26187606

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Project description:Background and aimsThe genus Arachis contains 80 described species. Section Arachis is of particular interest because it includes cultivated peanut, an allotetraploid, and closely related wild species, most of which are diploids. This study aimed to analyse the genetic relationships of multiple accessions of section Arachis species using two complementary methods. Microsatellites allowed the analysis of inter- and intraspecific variability. Intron sequences from single-copy genes allowed phylogenetic analysis including the separation of the allotetraploid genome components.MethodsIntron sequences and microsatellite markers were used to reconstruct phylogenetic relationships in section Arachis through maximum parsimony and genetic distance analyses.Key resultsAlthough high intraspecific variability was evident, there was good support for most species. However, some problems were revealed, notably a probable polyphyletic origin for A. kuhlmannii. The validity of the genome groups was well supported. The F, K and D genomes grouped close to the A genome group. The 2n = 18 species grouped closer to the B genome group. The phylogenetic tree based on the intron data strongly indicated that A. duranensis and A. ipaënsis are the ancestors of A. hypogaea and A. monticola. Intron nucleotide substitutions allowed the ages of divergences of the main genome groups to be estimated at a relatively recent 2·3-2·9 million years ago. This age and the number of species described indicate a much higher speciation rate for section Arachis than for legumes in general.ConclusionsThe analyses revealed relationships between the species and genome groups and showed a generally high level of intraspecific genetic diversity. The improved knowledge of species relationships should facilitate the utilization of wild species for peanut improvement. The estimates of speciation rates in section Arachis are high, but not unprecedented. We suggest these high rates may be linked to the peculiar reproductive biology of Arachis.

Project description:Many studies on Heracleum have shown poor correspondence between observed molecular clusters and established taxonomic classification amongst closely related species. This might reflect both unresolved taxonomy but perhaps also a lack of good genetic markers. This lack of appropriate and cost effective species-specific genetic markers hinders a resolved relationship for the species complex, and this in turn causes profound management challenges for a genus that contains both endemic species, with important ecological roles, and species with an invasive potential. Microsatellites are traditionally considered markers of choice for comprehensive, yet inexpensive, analyses of genetic variation, including examination of population structure, species identity, linkage map construction and cryptic speciation. In this study, we have used double digest restriction site associated DNA sequencing (ddRADseq) to develop microsatellite markers in Heracleum rechingeri. Genomic DNA from three individuals were digested with Sbf1 and Nde1 and size selected for library construction. The size-selected fragments were sequenced on an Ion Torrent sequencer and a total of 54 microsatellite sequences were bioinformatically confirmed. Twenty five loci were then tested for amplification, resulting in 19 of these being successfully amplified across eight species, comprising both the so-called thick-stemmed species (H. persicum, H. rechingeri, H. gorganicum and H. lasiopetalum), and thin-stemmed species (H. anisactis, H. pastinasifolium and H. transcaucasicum). Both Bayesian and distance-based clustering, and principal coordinate analyses clearly separated these into two groups. Surprisingly, three H. pastinacifolium populations were not separated from populations of the morphologically similar endemic species, H. anisactis, suggesting lack of genetic differentiation. Likewise, high genetic similarity was found between H. persicum and H. rechingeri populations, questioning taxonomic separation at the species level between these taxa. Further analyses are needed to re-evaluate the taxonomic significance of observed morphological variability currently applied to distinguish these sister taxa. Nevertheless, our results represent progress in the effort to develop cost-efficient molecular tools for species discrimination in this genus.

Project description:BackgroundAdoption of genomics based breeding has emerged as a promising approach for achieving comprehensive crop improvement. Such an approach is more relevant in the case of perennial species like mulberry. However, unavailability of genomic resources of co-dominant marker systems has been the major constraint for adopting molecular breeding to achieve genetic enhancement of Mulberry. The goal of this study was to develop and characterize a large number of locus specific genic and genomic SSR markers which can be effectively used for molecular characterization of mulberry species/genotypes.ResultWe analyzed a total of 3485 DNA sequences including genomic and expressed sequences (ESTs) of mulberry (Morus alba L.) genome. We identified 358 sequences to develop appropriate microsatellite primer pairs representing 222 genomic and 136 EST regions. Primers amplifying locus specific regions of Dudia white (a genotype of Morus alba L), were identified and 137 genomic and 51 genic SSR markers were standardized. A two pronged strategy was adopted to assess the applicability of these SSR markers using mulberry species and genotypes along with a few closely related species belonging to the family Moraceae viz., Ficus, Fig and Jackfruit. While 100% of these markers amplified specific loci on the mulberry genome, 79% were transferable to other related species indicating the robustness of these markers and the potential they hold in analyzing the molecular and genetic diversity among mulberry germplasm as well as other related species. The inherent ability of these markers in detecting heterozygosity combined with a high average polymorphic information content (PIC) of 0.559 ranging between 0.076 and 0.943 clearly demonstrates their potential as genomic resources in diversity analysis. The dissimilarity coefficient determined based on Neighbor joining method, revealed that the markers were successful in segregating the mulberry species, genotypes and other related species into distinct clusters.ConclusionWe report a total of 188 genomic and genic SSR markers in Morus alba L. A large proportion of these markers (164) were polymorphic both among mulberry species and genotypes. A substantial number of these markers (149) were also transferable to other related species like Ficus, Fig and Jackfruit. The extent of polymorphism revealed and the ability to detect heterozygosity among the cross pollinated mulberry species and genotypes render these markers an invaluable genomic resource that can be utilized in assessing molecular diversity as well as in QTL mapping and subsequently mulberry crop improvement through MAS.

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Genetic differentiation and hybrid identification using microsatellite markers in closely related wild species.

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Genetic differentiation and hybrid identification using microsatellite markers in closely related wild species.

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