Transcriptome Sequencing of Diverse Peanut (Arachis) Wild Species and the Cultivated Species Reveals a Wealth of Untapped Genetic Variability

Abstract To test the hypothesis that the cultivated peanut species possesses almost no molecular variability, we sequenced a diverse panel of 22 Arachis accessions representing Arachis hypogaea botanical classes, A-, B-, and K- genome diploids, a synthetic amphidiploid, and a tetraploid wild species. RNASeq was performed on pools of three tissues, and de novo assembly was performed. Realignment of individual accession reads to transcripts of the cultivar OLin identified 306,820 biallelic SNPs. Among 10 naturally occurring tetraploid accessions, 40,382 unique homozygous SNPs were identified in 14,719 contigs. In eight diploid accessions, 291,115 unique SNPs were identified in 26,320 contigs. The average SNP rate among the 10 cultivated tetraploids was 0.5, and among eight diploids was 9.2 per 1000 bp. Diversity analysis indicated grouping of diploids according to genome classification, and cultivated tetraploids by subspecies. Cluster analysis of variants indicated that sequences of B genome species were the most similar to the tetraploids, and the next closest diploid accession belonged to the A genome species. A subset of 66 SNPs selected from the dataset was validated; of 782 SNP calls, 636 (81.32%) were confirmed using an allele-specific discrimination assay. We conclude that substantial genetic variability exists among wild species. Additionally, significant but lesser variability at the molecular level occurs among accessions of the cultivated species. This survey is the first to report significant SNP level diversity among transcripts, and may explain some of the phenotypic differences observed in germplasm surveys. Understanding SNP variants in the Arachis accessions will benefit in developing markers for selection.

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Molecular biogeographic study of recently described B- and A-genome Arachis species, also providing new insights into the origins of cultivated peanut

Genome ◽

10.1139/g08-094 ◽

2009 ◽

Vol 52 (2) ◽

pp. 107-119 ◽

Cited By ~ 34

Author(s):

Mark D. Burow ◽

Charles E. Simpson ◽

Michael W. Faries ◽

James L. Starr ◽

Andrew H. Paterson

Keyword(s):

Wild Species ◽

Rflp Markers ◽

Species Variation ◽

Additional Species ◽

Marker Haplotype ◽

Genome Species ◽

B Genome ◽

A Genome ◽

Cultivated Peanut ◽

Arachis Batizocoi

The cultivated peanut Arachis hypogaea is a tetraploid, likely derived from A- and B-genome species. Reproductive isolation of the cultigen has resulted in limited genetic variability for important traits. Artificial hybridizations using selected diploid parents have introduced alleles from wild species, but improved understanding of recently classified B-genome accessions would aid future introgression work. To this end, 154 cDNA probes were used to produce 1887 RFLP bands scored on 18 recently classified or potential B-genome accessions and 16 previously identified species. One group of B-genome species consisted of Arachis batizocoi , Arachis cruziana , Arachis krapovickasii , and one potential additional species; a second consisted of Arachis ipaënsis , Arachis magna , and Arachis gregoryi . Twelve uncharacterized accessions grouped with A-genome species. Many RFLP markers diagnostic of A. batizocoi group specificity mapped to linkage group pair 2/12, suggesting selection or genetic control of chromosome pairing. The combination of Arachis duranensis and A. ipaënsis most closely reconstituted the marker haplotype of A. hypogaea, but differences allow for other progenitors or genetic rearrangements after polyploidization. From 2 to 30 alleles per locus were present, demonstrating section Arachis wild species variation of potential use for expanding the cultigen’s genetic basis.

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Characterization of genomes of timothy (Phleum pratense L.). I. Karyotypes and C-banding patterns in cultivated timothy and two wild relatives

Genome ◽

10.1139/g91-009 ◽

1991 ◽

Vol 34 (1) ◽

pp. 52-58 ◽

Cited By ~ 18

Author(s):

Q. Cai ◽

M. R. Bullen

Keyword(s):

Phleum Pratense ◽

Wild Relatives ◽

Banding Patterns ◽

C Banding ◽

B Genome ◽

A Genome ◽

Cultivated Species ◽

Genome Donors ◽

Phleum Pratense L

In an attempt to know the phylogeny of timothy (Phleum pratense), the cultivated species and two wild relatives, Phleum alpinum and Phleum bertolonii, were karyotyped with conventional and Giemsa C-banding methods. In the hexaploid P. pratense (2n = 6x = 42), two sets of seven chromosomes were indistinguishable from each other both in morphology and in banding patterns and the third set of seven was found to be differentiated from them. Two genomes, A and B, were tentatively established. The banded karyotype in diploid P. alpinum (2n = 2x = 14) was close to the A genome, which was tetraploid in P. pratense, and the karyotype in P. bertolonii (2n = 2x = 14) was analogous to the B genome in P. pratense, which suggests these species were the genome donors of P. pratense.Key words: chromosome, genome, allopolyploid, Giemsa C-banding.

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Further data on the genomic relationships among wild perennial species (2n = 40) of the genus Glycine Willd.

Genome ◽

10.1139/g88-029 ◽

1988 ◽

Vol 30 (2) ◽

pp. 166-176 ◽

Cited By ~ 33

Author(s):

R. J. Singh ◽

K. P. Kollipara ◽

T. Hymowitz

Keyword(s):

Current Status ◽

Evolutionary Divergence ◽

Similar Species ◽

Meiotic Pairing ◽

Perennial Species ◽

Genome Species ◽

B Genome ◽

A Genome ◽

Genomic Relationships ◽

Hybrid Weakness

The present study furnishes information about the current status of knowledge concerning the genomic relationships among 9 of the 12 wild perennial species (2n = 40) of the subgenus Glycine. Crossability rate, hybrid inviability, and meiotic pairing in intra- and inter-specific F1 hybrids revealed that genomically similar species, though morphologically distinct, crossed readily to produce hybrid progeny that were vigorous, fertile, and normal in meiotic pairing (20 bivalents at metaphase I). However, a chromatin bridge and acentric fragment were recorded in certain hybrid combinations, suggesting that the evolutionary divergence in genomically similar species occurred because of paracentric inversions. In contrast, crosses between genomically dissimilar species set pods that often aborted, showed hybrid weakness, seedling and vegetative lethality, seed inviability, and complete sterility. The sterility was attributed to disturbed meiotic pairing. It is obvious from this study that A-genome species such as G. canescens (AA) G. clandestina (intermediate pod, A1A1, and long pod, A2A2), and G. argyrea (A3A3), and B-genome species such as G. microphylla (BB), G. latifolia (B1B1), and G. tabacina (B2B2) predominate in the subgenus Glycine. Glycine cyrtoloba (CC) showed stronger genome homology to B-genome species than to A-genome species. Likewise, G. tomentella (DD) appeared to be more closely associated with A-genome species than to B-genome species. Although tomentellas with 38 and 40 chromosomes were indistinguishable morphologically, they differed genomically. Therefore, genome symbol EE was assigned to the 38-chromosome G. tomentella. Glycine falcata (FF) was found to be the most unusual species because it showed negligible chromosome homology with A- and B-genome species and did not set pods when cross-pollinated by C-, D-, and E-genome species.Key words: Glycine spp., genome, hybridization.

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An overview of peanut and its wild relatives

Plant Genetic Resources ◽

10.1017/s1479262110000444 ◽

2011 ◽

Vol 9 (01) ◽

pp. 134-149 ◽

Cited By ~ 65

Author(s):

David J. Bertioli ◽

Guillermo Seijo ◽

Fabio O. Freitas ◽

José F. M. Valls ◽

Soraya C. M. Leal-Bertioli ◽

...

Keyword(s):

Wild Species ◽

Crop Improvement ◽

Genomic Analysis ◽

Linkage Drag ◽

Root Knot Nematode ◽

Hybrid Identities ◽

B Genome ◽

Cultivated Peanut ◽

Recent Origin ◽

The Tropics

The legumeArachis hypogaea, commonly known as peanut or groundnut, is a very important food crop throughout the tropics and sub-tropics. The genus is endemic to South America being mostly associated with the savannah-like Cerrado. All species in the genus are unusual among legumes in that they produce their fruit below the ground. This profoundly influences their biology and natural distributions. The species occur in diverse habitats including grasslands, open patches of forest and even in temporarily flooded areas. Based on a number of criteria, including morphology and sexual compatibilities, the 80 described species are arranged in nine infrageneric taxonomic sections. While most wild species are diploid, cultivated peanut is a tetraploid. It is of recent origin and has an AABB-type genome. The most probable ancestral species areArachis duranensisandArachis ipaënsis, which contributed the A and B genome components, respectively. Although cultivated peanut is tetraploid, genetically it behaves as a diploid, the A and B chromosomes only rarely pairing during meiosis. Although morphologically variable, cultivated peanut has a very narrow genetic base. For some traits, such as disease and pest resistance, this has been a fundamental limitation to crop improvement using only cultivated germplasm. Transfer of some wild resistance genes to cultivated peanut has been achieved, for instance, the gene for resistance to root-knot nematode. However, a wider use of wild species in breeding has been hampered by ploidy and sexual incompatibility barriers, by linkage drag, and historically, by a lack of the tools needed to conveniently confirm hybrid identities and track introgressed chromosomal segments. In recent years, improved knowledge of species relationships has been gained by more detailed cytogenetic studies and molecular phylogenies. This knowledge, together with new tools for genetic and genomic analysis, will help in the more efficient use of peanut's genetic resources in crop improvement.

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Single-cell reconstitution reveals persistence of clonal heterogeneity in the murine hematopoietic system

10.1101/2021.06.28.450120 ◽

2021 ◽

Author(s):

Nadiya Kubasova ◽

Clara F. Alves-Pereira ◽

Saumya Gupta ◽

Svetlana Vinogradova ◽

Alexander Gimelbrant ◽

...

Keyword(s):

De Novo ◽

Phenotypic Diversity ◽

Cell Lineage ◽

Allelic Expression ◽

Monoallelic Expression ◽

Hematopoietic Stem ◽

Lineage Differentiation ◽

A Genome ◽

Allele Specific

The persistence of patterns of monoallelic expression is a controversial matter. We report a genome-wide in vivo transcriptomics approach based on allelic expression imbalance to evaluate whether the transcriptional allelic patterns of single murine hematopoietic stem cells (HSC) are still present in the respective differentiated clonal B-cell populations. For 14 genes, we show conclusive evidence for a remarkable persistence in HSC-derived B clonal cells of allele-specific autosomal transcriptional states already present in HSCs. In a striking contrast to the frequency of genes with clonal allelic expression differences in clones expanded without differentiation (up to 10%), we find that clones that have undergone multiple differentiation steps in vivo are more similar to each other. These data suggest that most of the random allele-specific stable transcriptional states on autosomal chromosomes are established de novo during cell lineage differentiation. Given that allele-specific transcriptional states are more stable in cells not undergoing extensive differentiation than in the clones we assessed after full lineage differentiation in vivo, we introduce the "Punctuated Disequilibria" model: random allelic expression biases are stable if the cells are not undergoing differentiation, but may change during differentiation between developmental stages and reach a new stable equilibrium that will only be challenged if the cell engages in further differentiation. Thus, the transcriptional allelic states may not be a stable feature of the differentiating clone, but phenotypic diversity between clones of a population at any given stage of the cell lineage is still ensured.

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The Use of DNA Sequences from the β-Amylase Gene to Determine the Genetic Relationship among Sweetpotato, I. batatas and Other Ipomoea Species in Series Batatas (Convolvulaceae)

HortScience ◽

10.21273/hortsci.40.4.1121e ◽

2005 ◽

Vol 40 (4) ◽

pp. 1121E-1122

Author(s):

Sriyani Rajapakse ◽

Janice Ryan-Bohac ◽

Sasanda Nilmalgoda ◽

Robert Ballard ◽

Daniel F. Austin

Keyword(s):

Dna Sequences ◽

Ipomoea Batatas ◽

Dna Flow Cytometry ◽

Amylase Gene ◽

Genome Species ◽

B Genome ◽

A Genome ◽

Nucleotide Sequence Variation ◽

In Series ◽

True Hybrid

The sweet potato Ipomoea batatas (L.) Lam. is classified in series Batatas (Choisy) in Convolvulaceae, with 12 other species and an interspecific true hybrid. The phylogenetic relationships of a sweetpotato cultivar and 13 accessions of Ipomoeas in the series Batatas were investigated using the nucleotide sequence variation of the nuclear-encoded β-amylase gene. First, flowers were examined to identify the species, and DNA flow cytometry used to determine their ploidy. The sweetpotato accession was confirmed as a hexaploid, I. tabascana a tetraploid, and all other species were diploids. A 1.1–1.3 kb fragment of the β-amylase gene spanning two exons separated by a long intron was PCR-amplified, cloned, and sequenced. Exon sequences were highly conserved, while the intron yielded large sequence differences. Intron analysis grouped species currently recognized as A and B genome types into separate clades. This grouping supported the prior classification of all the species, with one exception. The species I. tiliacea was previously classified as a B genome species, but this DNA study classifies it as an A genome species. From the intron alignment, sequences specific to both A and B genome species were identified. Exon sequences indicated that I. ramosissima and I. umbraticola were quite different from other A genome species. Placement of I. littoralis was questionable: its introns were similar to other B genome species, but exons were quite different. Exon evolution indicated the B genome species evolved faster than A genome species. Both intron and exon results indicated the B genome species most closely related to sweetpotato (I. batatas) were I. trifida and I. tabascana.

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An Unbiased Predictive Model to Detect DNA Methylation Propensity of CpG Islands in the Human Genome

Current Bioinformatics ◽

10.2174/1574893615999200724145835 ◽

2020 ◽

Vol 15 ◽

Author(s):

Dicle Yalcin ◽

Hasan H. Otu

Keyword(s):

Model Building ◽

De Novo ◽

Cpg Islands ◽

Treatment Strategies ◽

Area Under The Curve ◽

Global Methylation ◽

Sequence Features ◽

A Genome ◽

Combined Features ◽

Epigenetic Repression

Background: Epigenetic repression mechanisms play an important role in gene regulation, specifically in cancer development. In many cases, a CpG island’s (CGI) susceptibility or resistance to methylation are shown to be contributed by local DNA sequence features. Objective: To develop unbiased machine learning models–individually and combined for different biological features–that predict the methylation propensity of a CGI. Methods: We developed our model consisting of CGI sequence features on a dataset of 75 sequences (28 prone, 47 resistant) representing a genome-wide methylation structure. We tested our model on two independent datasets that are chromosome (132 sequences) and disease (70 sequences) specific. Results: We provided improvements in prediction accuracy over previous models. Our results indicate that combined features better predict the methylation propensity of a CGI (area under the curve (AUC) ~0.81). Our global methylation classifier performs well on independent datasets reaching an AUC of ~0.82 for the complete model and an AUC of ~0.88 for the model using select sequences that better represent their classes in the training set. We report certain de novo motifs and transcription factor binding site (TFBS) motifs that are consistently better in separating prone and resistant CGIs. Conclusion: Predictive models for the methylation propensity of CGIs lead to a better understanding of disease mechanisms and can be used to classify genes based on their tendency to contain methylation prone CGIs, which may lead to preventative treatment strategies. MATLAB and Python™ scripts used for model building, prediction, and downstream analyses are available at https://github.com/dicleyalcin/methylProp_predictor.

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Genomic Characterization Provides an Insight into the Pathogenicity of the Poplar Canker Bacterium Lonsdalea populi

Genes ◽

10.3390/genes12020246 ◽

2021 ◽

Vol 12 (2) ◽

pp. 246

Author(s):

Xiaomeng Chen ◽

Rui Li ◽

Yonglin Wang ◽

Aining Li

Keyword(s):

Genome Sequence ◽

Extracellular Enzymes ◽

De Novo ◽

Whole Genome Sequence ◽

Hybrid Poplars ◽

A Genome ◽

Conserved Genes ◽

Genomic Characterization ◽

Molecular Bases ◽

Insight Into

An emerging poplar canker caused by the gram-negative bacterium, Lonsdalea populi, has led to high mortality of hybrid poplars Populus × euramericana in China and Europe. The molecular bases of pathogenicity and bark adaptation of L. populi have become a focus of recent research. This study revealed the whole genome sequence and identified putative virulence factors of L. populi. A high-quality L. populi genome sequence was assembled de novo, with a genome size of 3,859,707 bp, containing approximately 3434 genes and 107 RNAs (75 tRNA, 22 rRNA, and 10 ncRNA). The L. populi genome contained 380 virulence-associated genes, mainly encoding for adhesion, extracellular enzymes, secretory systems, and two-component transduction systems. The genome had 110 carbohydrate-active enzyme (CAZy)-coding genes and putative secreted proteins. The antibiotic-resistance database annotation listed that L. populi was resistant to penicillin, fluoroquinolone, and kasugamycin. Analysis of comparative genomics found that L. populi exhibited the highest homology with the L. britannica genome and L. populi encompassed 1905 specific genes, 1769 dispensable genes, and 1381 conserved genes, suggesting high evolutionary diversity and genomic plasticity. Moreover, the pan genome analysis revealed that the N-5-1 genome is an open genome. These findings provide important resources for understanding the molecular basis of the pathogenicity and biology of L. populi and the poplar-bacterium interaction.

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A Microsatellite Map of Wheat

Genetics ◽

10.1093/genetics/149.4.2007 ◽

1998 ◽

Vol 149 (4) ◽

pp. 2007-2023 ◽

Cited By ~ 8

Author(s):

Marion S Röder ◽

Victor Korzun ◽

Katja Wendehake ◽

Jens Plaschke ◽

Marie-Hélène Tixier ◽

...

Keyword(s):

Bread Wheat ◽

Reference Population ◽

Triticum Aestivum L ◽

Wheat Genome ◽

D Genome ◽

B Genome ◽

Microsatellite Map ◽

A Genome ◽

Polymorphic Microsatellite ◽

Primer Sets

Abstract Hexaploid bread wheat (Triticum aestivum L. em. Thell) is one of the world's most important crop plants and displays a very low level of intraspecific polymorphism. We report the development of highly polymorphic microsatellite markers using procedures optimized for the large wheat genome. The isolation of microsatellite-containing clones from hypomethylated regions of the wheat genome increased the proportion of useful markers almost twofold. The majority (80%) of primer sets developed are genome-specific and detect only a single locus in one of the three genomes of bread wheat (A, B, or D). Only 20% of the markers detect more than one locus. A total of 279 loci amplified by 230 primer sets were placed onto a genetic framework map composed of RFLPs previously mapped in the reference population of the International Triticeae Mapping Initiative (ITMI) Opata 85 × W7984. Sixty-five microsatellites were mapped at a LOD >2.5, and 214 microsatellites were assigned to the most likely intervals. Ninety-three loci were mapped to the A genome, 115 to the B genome, and 71 to the D genome. The markers are randomly distributed along the linkage map, with clustering in several centromeric regions.

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riboCIRC: a comprehensive database of translatable circRNAs

Genome Biology ◽

10.1186/s13059-021-02300-7 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Huihui Li ◽

Mingzhe Xie ◽

Yan Wang ◽

Ludong Yang ◽

Zhi Xie ◽

...

Keyword(s):

De Novo ◽

Species Conservation ◽

Structure And Function ◽

Research Community ◽

Genome Browser ◽

Valuable Resource ◽

Sequence Structure ◽

A Genome ◽

Context Specific ◽

And Function

AbstractriboCIRC is a translatome data-oriented circRNA database specifically designed for hosting, exploring, analyzing, and visualizing translatable circRNAs from multi-species. The database provides a comprehensive repository of computationally predicted ribosome-associated circRNAs; a manually curated collection of experimentally verified translated circRNAs; an evaluation of cross-species conservation of translatable circRNAs; a systematic de novo annotation of putative circRNA-encoded peptides, including sequence, structure, and function; and a genome browser to visualize the context-specific occupant footprints of circRNAs. It represents a valuable resource for the circRNA research community and is publicly available at http://www.ribocirc.com.

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