Recent improvements in genetic analysis and genotyping methods have resulted in a rapid expansion of the power of molecular markers to address ecological questions. Microsatellites have emerged as the most popular and versatile marker type for ecological applications. The rise of commercial services that can isolate microsatellites for new study species and genotype samples at reasonable prices presents ecologists with the unprecedented ability to employ genetic approaches without heavy investment in specialized equipment. Nevertheless, the lack of accessible, synthesized information on the practicalities and pitfalls of using genetic tools impedes ecologists ability to make informed decisions on using molecular approaches and creates the risk that some will use microsatellites without understanding the steps needed to evaluate the quality of a genetic data set. The first goal of this synthesis is to provide an overview of the strengths and limitations of microsatellite markers and the risks, cost and time requirements of isolating and using microsatellites with the aid of commercial services. The second goal is to encourage the use and consistent reporting of thorough marker screening to ensure high quality data. To that end, we present a multistep screening process to evaluate candidate loci for inclusion in a genetic study that is broadly targeted to both novice and experienced geneticists alike.

Microsatellites for ecologists: a practical guide to using and evaluating microsatellite markers

PREFACE REPETITIVE DNA: AN IMPORTANT SOURCE OF VARIATION IN EUKARYOTIC GENOMES Categories of DNA Sequence Mutations Tandem-Repetitive DNA: The Biology of Mini- and Microsatellites Minisatellites Microsatellites Transposable Elements Class I Transposons Class II Transposons Unclassified Transposons Transposons and Genome Evolution Transposons as Molecular Markers DETECTING DNA VARIATION BY MOLECULAR MARKERS Properties of Molecular Markers Traditional Marker Systems Protein Markers and Allozymes DNA Sequencing Restriction Fragment Length Polymorphism (RFLP) Analysis The PCR Generation: Molecular Markers Based on In Vitro DNA Amplification Principle of the PCR Cleaved Amplified Polymorphic Sequences PCR with Arbitrary Primers: RAPD and Its Variants Microsatellites Inter-Repeat PCR DNA Profiling of Genic Regions: Resistance Gene Analog Polymorphism, Sequence-Related Amplified Polymorphism, and Target Region Amplification Polymorphism Hybridization of Microsatellites to RAPD and MP-PCR Products AFLP Analysis and Its Variants Single-Strand Conformation Polymorphism Analysis and Related Techniques Miscellaneous Techniques LABORATORY EQUIPMENT METHODOLOGY Safety Precautions Isolation, Purification, and Quantitation of Plant DNA Collection and Preservation of Plant Tissue in the Field Plant DNA Extraction: General Considerations CTAB Protocol I CTAB Protocol II SDS-Potassium Acetate Protocol DNA Preparation via Nuclei Quantitation of DNA Basic Molecular Techniques Restriction of DNA Polymerase Chain Reaction DNA Sequencing Agarose Gel Electrophoresis PAA Gel Electrophoresis Detection of DNA in Gels Gel Drying Southern Blotting Generation of Radiolabeled Probes, Primers, and PCR Products Blot Hybridization Signal Detection PCR with Arbitrary Primers Standard RAPD Protocol Influence of Reaction Conditions and Components Modifications Microsatellite-Primed PCR Standard Protocol of Microsatellite-Primed PCR Influence of Reaction Conditions and Components Modifications PCR and Hybridization: Combinatory Techniques Assessing the Genomic Copy Number of PCR Amplicons Testing the Homology of Comigrating Bands Random Amplified Polymorphic Microsatellites Amplified Fragment Length Polymorphism Standard AFLP Protocol Using Radioisotopes AFLP Protocol Using Fluorescence-Labeled Primers Selective Amplification of Microsatellite Polymorphic Loci and Microsatellite AFLP Protocols Technical Aspects and Modifications Robustness and Reproducibility Generation and Analysis of Microsatellite Markers Microsatellite Analysis Using Radioisotopes Microsatellite Analysis Using Fluorochromes Technical Aspects and Modifications Generating Microsatellite Markers Without Cloning Microsatellite Cloning CAPS Analysis of cpDNA and mtDNA Standard CAPS Protocol Choice of CAPS Primers EVALUATION OF MOLECULAR MARKER DATA Robustness and Reproducibility Reliability Band Homology Band Linkage and Neutrality Fragment Sizing and Matching General Precautions Equipment Multilocus vs. Single-Locus Approaches Multilocus Markers Single-Locus Markers and Polyploids Band Sharing and Genetic Distances Coefficients of Similarity Dissimilarity Coefficients and Genetic Distances Identity and Uniqueness Clonal Structure Ordination, Clustering, and Dendrograms Ordination Techniques Construction of Dendrograms Population Genetic Analysis Measures of Variation Genetic Differentiation between Populations Genetic Distances between Populations Inbreeding Coefficient and Mating Systems Estimation of Relatedness and Paternity Testing Migration and Hybridization Gene Flow, Isolation-by-Distance, and Spatial Structure Phylogeography and Nested Clade Analysis Statistical Testing of Hypotheses: Analytical and Computational Methods APPLICATIONS OF DNA FINGERPRINTING IN PLANT SCIENCES A Brief History of DNA Fingerprinting Minisatellite and Oligonucleotide DNA Probes Detect Genetic Variation PCR-Based Methods Enter the Stage Microsatellite DNA Analyses Yield Codominant Markers Universal Organellar DNA Primers Produce Uniparental Markers Genotype Identification Individual-Specific DNA Fingerprints Cultivar Identification In Vitro-Propagated Plant Material and Somaclonal Variation Sports and Other Mutants Genetic Diversity Variation and Relatedness among Cultivars Analysis of Population Genetic Diversity and Its Distribution Hybridization and Introgression Plant Conservation Germplasm Characterization and Preservation Plant Taxonomy and Systematics Taxonomic Relationships Revealed by Multilocus DNA Methods Microsatellite Markers in Taxonomic Studies Taxonomic Consequences from DNA Profiling Data Phylogeography Phylogeography Based on cpDNA Phylogeography Based on Nuclear Genes LINKAGE ANALYSIS AND GENETIC MAPS Generating High-Density Genetic Maps Selection of Parent Plants Mapping Population Linkage Analysis The Genetic Map Cytogenetic Maps Genetic vs. Physical Maps Synteny: The Comparative Analysis of Genomes Marker-Assisted Selection Molecular Markers and Positional Cloning WHICH MARKER FOR WHAT PURPOSE: A COMPARISON Morphological Characters and Allozymes vs. DNA Markers Different Kinds of DNA Markers Discriminatory Power Genetic Distances Within- and Among-Population Variation Gene Tagging and Genetic Linkage Mapping Costs Conclusions FUTURE PROSPECTS: SNIPS AND CHIPS FOR DNA AND RNA PROFILING Single-Nucleotide Polymorphisms What Is a SNiP SNP Discovery DNA Microarrays Expression Profiling and Expression Markers APPENDIX 1: PLANT DNA ISOLATION PROTOCOLS APPENDIX 2: SUPPLIERS AND SELLERS OF REAGENTS AND EQUIPMENT APPENDIX 3: COMPUTER PROGRAMS DEALING WITH THE EVALUATION OF DNA SEQUENCE VARIATION AND MOLECULAR MARKER DATA APPENDIX 4: WEB PAGES OF INTEREST REFERENCES INDEX

DNA fingerprinting in plants: principles, methods, and applications

Agriculture is the lever with which humans transformed the earth over the last 10,000 years and created new forms of plant and animal species that have forever altered the face of the planet In the last decade, significant technological and methodological advances in both molecular biology and archaeology have revolutionized the study of plant and animal domestication and are reshaping our understanding of the transition from foraging to farming, one of the major turning points in human history This groundbreaking volume for the first time brings together leading archaeologists and biologists working on the domestication of both plants and animals to consider a wide variety of archaeological and genetic approaches to tracing the origin and dispersal of domesticates It provides a comprehensive overview of the state of the art in this quickly changing field as well as reviews of recent findings on specific crop and livestock species in the Americas, Eurasia, and Africa Offering a unique global perspective, it explores common challenges and potential avenues for future progress in documenting domestication

Documenting Domestication: New Genetic and Archaeological Paradigms

Sesame is an important oil crop, but limited transcriptomic and genomic data are currently available. This information is essential to clarify the fatty acid and lignan biosynthesis molecular mechanism. In addition, a shortage of sesame molecular markers limits the efficiency and accuracy of genetic breeding. High-throughput transcriptomic sequencing is essential to generate a large transcriptome sequence dataset for gene discovery and molecular marker development. Sesame transcriptomes from five tissues were sequenced using Illumina paired-end sequencing technology. The cleaned raw reads were assembled into a total of 86,222 unigenes with an average length of 629 bp. Of the unigenes, 46,584 (54.03%) had significant similarity with proteins in the NCBI nonredundant protein database and Swiss-Prot database (E-value < 10-5). Of these annotated unigenes, 10,805 and 27,588 unigenes were assigned to gene ontology categories and clusters of orthologous groups, respectively. In total, 22,003 (25.52%) unigenes were mapped onto 119 pathways using the Kyoto Encyclopedia of Genes and Genomes Pathway database (KEGG). Furthermore, 44,750 unigenes showed homology to 15,460 Arabidopsis genes based on BLASTx analysis against The Arabidopsis Information Resource (TAIR, Version 10) and revealed relatively high gene coverage. In total, 7,702 unigenes were converted into SSR markers (EST-SSR). Dinucleotide SSRs were the dominant repeat motif (67.07%, 5,166), followed by trinucleotide (24.89%, 1,917), tetranucleotide (4.31%, 332), hexanucleotide (2.62%, 202), and pentanucleotide (1.10%, 85) SSRs. AG/CT (46.29%) was the dominant repeat motif, followed by AC/GT (16.07%), AT/AT (10.53%), AAG/CTT (6.23%), and AGG/CCT (3.39%). Fifty EST-SSRs were randomly selected to validate amplification and to determine the degree of polymorphism in the genomic DNA pools. Forty primer pairs successfully amplified DNA fragments and detected significant amounts of polymorphism among 24 sesame accessions. This study demonstrates that Illumina paired-end sequencing is a fast and cost-effective approach to gene discovery and molecular marker development in non-model organisms. Our results provide a comprehensive sequence resource for sesame research.

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Characterization of the sesame ( Sesamum indicum L.) global transcriptome using Illumina paired-end sequencing and development of EST-SSR markers

Triticum aestivum L.

We investigated the transferability of 31 soybean (Glycine max) simple sequence repeat (SSR) loci to wild congeners and to other legume genera. Up to 65% of the soybean primer pairs amplified SSRs within Glycine, but frequently, the SSRs were short and interrupted compared with those of soybeans. Nevertheless, 85% of the loci were polymorphic within G. clandestina. Cross-species amplification outside of the genus was much lower (3%-13%), with polymorphism restricted to one primer pair, AG81. AG81 amplified loci in Glycine, Kennedia, and Vigna (Phaseoleae), Vicia (Vicieae), Trifolium (Trifolieae), and Lupinus (Genisteae) within the Papilionoideae, and in Albizia within the Mimosoideae. The primer conservation at AG81 may be explained by its apparent proximity to the seryl-tRNA synthetase gene. Interspecific differences in allele size at AG81 loci reflected repeat length variation within the SSR region and indels in the flanking region. Alleles of identical size with different underlying sequences (size homoplasy) were observed. Our findings and the emerging patterns in other plant studies suggest that in contrast to animals, successful cross-species amplification of SSRs in plants is largely restricted to congeners or closely related genera. Because mutations in both the SSR region and the flanking region contribute to variation in allele size among species, knowledge of DNA sequence is essential before SSR loci can be meaningfully used to address applied and evolutionary questions.

Cross-species amplification of soybean (Glycine max) simple sequence repeats (SSRs) within the genus and other legume genera: implications for the transferability of SSRs in plants.

S Gilmore

Papers

Cross-species amplification of soybean (Glycine max) simple sequence repeats (SSRs) within the genus and other legume genera: implications for the transferability of SSRs in plants.