No support for a meiosis suppressor in Daphnia pulex: Comparison of linkage maps reveals normal recombination in males of obligate parthenogenetic lineages.

2021 ◽  
Author(s):  
Cécile Molinier ◽  
Thomas Lenormand ◽  
Christoph R Haag
Keyword(s):  
Daphnia Pulex ◽  
Genetic Maps ◽  
Linkage Maps ◽  
Model Species ◽  
Recombination Rates ◽  
Entire Life ◽  
Entire Life Cycle ◽  
Genome Wide ◽  
Males And Females ◽  
Genomic Resource

It is often assumed that obligate parthenogenesis (OP) evolves by a disruption of meiosis and recombination. One emblematic example that appears to support this view is the crustacean Daphnia pulex. Here, by constructing high-density linkage maps, we estimate genome-wide recombination rates in males that are occasionally produced by OP lineages, as well as in males and females of cyclical parthenogenetic (CP) lineages. The results show no significant differences in recombination rates and patterns between CP and OP males nor between CP males and CP females. The observation that recombination is not suppressed in OP males invalidates the hypothesis of a general meiosis suppressor responsible for OP. Rather, our findings suggest that in D. pulex, as in other species where OP evolves from CP ancestors, the CP to OP transition evolves through a re-use of the parthenogenesis pathways already present in CP and through their extension to the entire life cycle, at least in females. In addition to the implications for the evolution of OP, the genetic maps produced by this study constitute an important genomic resource for the model species Daphnia.

scholarly journals Development of an SNP Marker Set for Marker-Assisted Backcrossing Using Genotyping-By-Sequencing in Tetraploid Perilla

2021 ◽  
Author(s):  
Yun-Joo Kang ◽  
Bo-Mi Lee ◽  
Jangmi Kim ◽  
Moon Nam ◽  
Myoung-Hee Lee ◽  
...  
Keyword(s):  
Recurrent Selection ◽  
Diploid Species ◽  
Genotyping By Sequencing ◽  
Snp Markers ◽  
Genetic Maps ◽  
Linkage Maps ◽  
Linkage Groups ◽  
Genome Wide ◽  
A Genome ◽  
Marker Assisted Backcrossing

Abstract High-quality molecular markers are essential for marker-assisted selection to accelerate breeding progress. Compared with diploid species, recently diverged polyploid crop species tend to have highly similar homeologous subgenomes, which is expected to limit the development of broadly applicable locus-specific single-nucleotide polymorphism (SNP) assays. Furthermore, it is particularly challenging to make genome-wide marker sets for species that lack a reference genome. Here, we report the development of a genome-wide set of kompetitive allele specific PCR (KASP) markers for marker-assisted recurrent selection (MARS) in the tetraploid minor crop perilla. To find locus-specific SNP markers across the perilla genome, we used genotyping-by-sequencing (GBS) to construct linkage maps of two F2 populations. The two resulting high-resolution linkage maps comprised 2,326 and 2,454 SNP markers that spanned a total genetic distance of 2,133 cM across 16 linkage groups and 2,169 cM across 21 linkage groups, respectively. We then obtained a final genetic map consisting of 22 linkage groups with 1,123 common markers from the two genetic maps. We selected 96 genome-wide markers for MARS and confirmed the accuracy of markers in the two F2 populations using a high-throughput Fluidigm system. We confirmed that 91.8% of the SNP genotyping results from the Fluidigm assay were the same as the results obtained through GBS. These results provide a foundation for marker-assisted backcrossing and the development of new varieties of perilla.

scholarly journals Systematic Analyses of Autosomal Recombination Rates from the 1000 Genomes Project Uncovers the Global Recombination Landscape in Humans

2018 ◽  
Author(s):  
Shivakumara Manu ◽  
Kshitish K Acharya ◽  
Saravanamuthu Thiyagarajan
Keyword(s):  
Meiotic Recombination ◽  
Genetic Maps ◽  
Human Populations ◽  
1000 Genomes Project ◽  
Recombination Rates ◽  
1000 Genomes ◽  
Genome Wide ◽  
Shared Ancestry ◽  
Genomic Locations ◽  
First Time

ABSTRACTBackgroundMeiotic recombination plays an important role in evolution by shuffling different alleles along the chromosomes, thus generating the genetic diversity across generations that is vital for adaptation. The plasticity of recombination rates and presence of hotspots of recombination along the genome has attracted much attention over two decades due to their contribution to the evolution of the genome. Yet, the variation in genome-wide recombination landscape and the differences in the location and strength of hotspots across worldwide human populations remains little explored.ResultsWe make use of the untapped linkage disequilibrium (LD) based genetic maps from the 1000 Genomes Project (1KGP) to perform in-depth analyses of finescale variation in the autosomal recombination rates across 20 human populations to uncover the global recombination landscape. We have generated a detailed map of human recombination landscape comprising of a comprehensive set of 88,841 putative hotspots and 80,129 coldspots with their respective strengths across populations, about 2/3rd of which were previously unknown. We have validated and assessed the number of historical putative hotspots derived from the patterns of LD that are currently active in the contemporary populations using a recently published high-resolution pedigree-based genetic map, constructed and refined using 3.38 million crossovers from various populations. For the first time, we provide statistics regarding the conserved, shared, and unique hotspots across all the populations studied.ConclusionsOur analysis yields clusters of continental groups, reflecting their shared ancestry and genetic similarities in the recombination rates that are linked to the migratory and evolutionary histories of the populations. We provide the genomic locations and strengths of hotspots and coldspots across all the populations studied which are a valuable set of resources arising out our analyses of 1KGP data. The findings are of great importance for further research on human hotspots as we approach the dusk of retiring HapMap-based resources.

scholarly journals VfODB: a comprehensive database of ESTs, EST-SSRs, mtSSRs, microRNA-target markers and genetic maps in Vicia faba

AoB Plants ◽  
2020 ◽  
Vol 12 (6) ◽  
Author(s):  
Morad M Mokhtar ◽  
Ebtissam H A Hussein ◽  
Salah El-Din S El-Assal ◽  
Mohamed A M Atia
Keyword(s):  
Vicia Faba ◽  
Faba Bean ◽  
Expressed Sequence Tags ◽  
Genetic Linkage ◽  
Genetic Maps ◽  
Linkage Maps ◽  
Microrna Target ◽  
Genetic Linkage Maps ◽  
Expressed Sequence ◽  
Simple Sequence

Abstract Faba bean (Vicia faba) is an essential food and fodder legume crop worldwide due to its high content of proteins and fibres. Molecular markers tools represent an invaluable tool for faba bean breeders towards rapid crop improvement. Although there have historically been few V. faba genome resources available, several transcriptomes and mitochondrial genome sequence data have been released. These data in addition to previously developed genetic linkage maps represent a great resource for developing functional markers and maps that can accelerate the faba bean breeding programmes. Here, we present the Vicia faba Omics database (VfODB) as a comprehensive database integrating germplasm information, expressed sequence tags (ESTs), expressed sequence tags-simple sequence repeats (EST-SSRs), and mitochondrial-simple sequence repeats (mtSSRs), microRNA-target markers and genetic maps in faba bean. In addition, KEGG pathway-based markers and functional maps are integrated as a novel class of annotation-based markers/maps. Collectively, we developed 31 536 EST markers, 9071 EST-SSR markers and 3023 microRNA-target markers based on V. faba RefTrans V2 mining. By mapping 7940 EST and 2282 EST-SSR markers against the KEGG pathways database we successfully developed 107 functional maps. Also, 40 mtSSR markers were developed based on mitochondrial genome mining. On the data curation level, we retrieved 3461 markers representing 12 types of markers (CAPS, EST, EST-SSR, Gene marker, INDEL, Isozyme, ISSR, RAPD, SCAR, RGA, SNP and SSR), which mapped across 18 V. faba genetic linkage maps. VfODB provides two user-friendly tools to identify, classify SSR motifs and in silico amplify their targets. VfODB can serve as a powerful database and helpful platform for faba bean research community as well as breeders interested in Genomics-Assisted Breeding.

scholarly journals Heterogeneity in Rates of Recombination Across the Mouse Genome

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 537-548 ◽  
Author(s):  
Michael W Nachman ◽  
Gary A Churchill
Keyword(s):  
Linkage Map ◽  
Genetic Map ◽  
Large Scale ◽  
Physical Map ◽  
Genetic Maps ◽  
Recombination Rates ◽  
Physical Maps ◽  
Genomic Patterns ◽  
Mary Lyon ◽  
Microsatellite Linkage

Abstract If loci are randomly distributed on a physical map, the density of markers on a genetic map will be inversely proportional to recombination rate. First proposed by MARY LYON, we have used this idea to estimate recombination rates from the Drosophila melanogaster linkage map. These results were compared with results of two other studies that estimated regional recombination rates in D. melanogaster using both physical and genetic maps. The three methods were largely concordant in identifying large-scale genomic patterns of recombination. The marker density method was then applied to the Mus musculus microsatellite linkage map. The distribution of microsatellites provided evidence for heterogeneity in recombination rates. Centromeric regions for several mouse chromosomes had significantly greater numbers of markers than expected, suggesting that recombination rates were lower in these regions. In contrast, most telomeric regions contained significantly fewer markers than expected. This indicates that recombination rates are elevated at the telomeres of many mouse chromosomes and is consistent with a comparison of the genetic and cytogenetic maps in these regions. The density of markers on a genetic map may provide a generally useful way to estimate regional recombination rates in species for which genetic, but not physical, maps are available.

scholarly journals A Consensus Map for Loblolly Pine (Pinus taeda L.). I. Construction and Integration of Individual Linkage Maps From Two Outbred Three-Generation Pedigrees

Genetics ◽  
1999 ◽  
Vol 151 (1) ◽  
pp. 321-330 ◽  
Author(s):  
Mitchell M Sewell ◽  
Bradley K Sherman ◽  
David B Neale
Keyword(s):  
Pinus Taeda ◽  
Loblolly Pine ◽  
Fragment Length Polymorphism ◽  
Random Amplified Polymorphic Dna ◽  
Mapping Function ◽  
Genetic Maps ◽  
Linkage Data ◽  
Linkage Maps ◽  
Consensus Map ◽  
Pinus Taeda L

Abstract A consensus map for loblolly pine (Pinus taeda L.) was constructed from the integration of linkage data from two unrelated three-generation outbred pedigrees. The progeny segregation data from restriction fragment length polymorphism, random amplified polymorphic DNA, and isozyme genetic markers from each pedigree were recoded to reflect the two independent populations of parental meioses, and genetic maps were constructed to represent each parent. The rate of meiotic recombination was significantly greater for males than females, as was the average estimate of genome length for males {1983.7 cM [Kosambi mapping function (K)]} and females [1339.5 cM(K)]. The integration of individual maps allows for the synthesis of genetic information from independent sources onto a single consensus map and facilitates the consolidation of linkage groups to represent the chromosomes (n = 12) of loblolly pine. The resulting consensus map consists of 357 unique molecular markers and covers ∼1300 cM(K).

scholarly journals First-Generation Linkage Map of the Gray, Short-Tailed Opossum,Monodelphis domestica, Reveals Genome-Wide Reduction in Female Recombination Rates

Genetics ◽  
2004 ◽  
Vol 166 (1) ◽  
pp. 307-329 ◽  
Author(s):  
Paul B. Samollow ◽  
Candace M. Kammerer ◽  
Susan M. Mahaney ◽  
Jennifer L. Schneider ◽  
Scott J. Westenberger ◽  
...  
Keyword(s):  
Linkage Map ◽  
First Generation ◽  
Monodelphis Domestica ◽  
Recombination Rates ◽  
Genome Wide

Epoxidation of juvenile hormone was a key innovation improving insect reproductive fitness

2021 ◽  
Vol 118 (45) ◽  
pp. e2109381118
Author(s):  
Marcela Nouzova ◽  
Marten J. Edwards ◽  
Veronika Michalkova ◽  
Cesar E. Ramirez ◽  
Marnie Ruiz ◽  
...  
Keyword(s):  
Life Cycle ◽  
Juvenile Hormone ◽  
Reproductive Performance ◽  
Reproductive Fitness ◽  
Fitness Cost ◽  
Evolutionary Significance ◽  
Methyl Farnesoate ◽  
Entire Life ◽  
Entire Life Cycle ◽  
Key Innovation

Methyl farnesoate (MF) plays hormonal regulatory roles in crustaceans. An epoxidated form of MF, known as juvenile hormone (JH), controls metamorphosis and stimulates reproduction in insects. To address the evolutionary significance of MF epoxidation, we generated mosquitoes completely lacking either of the two enzymes that catalyze the last steps of MF/JH biosynthesis and epoxidation, respectively: the JH acid methyltransferase (JHAMT) and the P450 epoxidase CYP15 (EPOX). jhamt−/− larvae lacking both MF and JH died at the onset of metamorphosis. Strikingly, epox−/− mutants, which synthesized MF but no JH, completed the entire life cycle. While epox−/− adults were fertile, the reproductive performance of both sexes was dramatically reduced. Our results suggest that although MF can substitute for the absence of JH in mosquitoes, it is with a significant fitness cost. We propose that MF can fulfill most roles of JH, but its epoxidation to JH was a key innovation providing insects with a reproductive advantage.

Rice metabolic regulatory network spanning its entire life cycle

2021 ◽  
Author(s):  
Chenkun Yang ◽  
Shuangqian Shen ◽  
Shen Zhou ◽  
Yufei Li ◽  
Yuyuan Mao ◽  
...  
Keyword(s):  
Life Cycle ◽  
Regulatory Network ◽  
Entire Life ◽  
Entire Life Cycle
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