scholarly journals A chromosome-scale assembly of allotetraploid Brassica juncea (AABB) elucidates comparative architecture of the A and B genomes

2019 ◽  
Author(s):  
Kumar Paritosh ◽  
Satish Kumar Yadava ◽  
Priyansha Singh ◽  
Latika Bhayana ◽  
Arundhati Mukhopadhyay ◽  
...  
Keyword(s):  
Brassica Juncea ◽  
Single Molecule ◽  
Genome Assembly ◽  
Diploid Species ◽  
Gene Clusters ◽  
Specific Gene ◽  
Dry Land ◽  
Gene Block ◽  
B Genome ◽  
A Genome

AbstractBrassica juncea (AABB; genome size ∼920 Mb), commonly referred to as mustard, is a natural allopolyploid of two diploid species – B. rapa (AA) and B. nigra (BB). We report a highly contiguous genome assembly of an oleiferous type of B. juncea variety Varuna, an archetypical Indian gene pool line of mustard, with ∼100x PacBio single-molecule real-time (SMRT) reads providing contigs with an N50 value of >5Mb. Assembled contigs were corrected and scaffolded with BioNano optical mapping. Three different linkage maps containing a large number of GBS markers were developed and used to anchor scaffolds/contigs to the 18 linkage groups of B. juncea. The resulting chromosome-scale assembly is a significant improvement over the previous draft assembly of B. juncea Tumida, a vegetable type of mustard. The assembled genome was characterized for transposons, centromeric repeats, gene content, and gene block associations. Both A and B genomes contain highly fragmented gene block arrangements. In comparison to the A genome, the B genome contains a significantly higher content of LTR/Gypsy retrotransposons, distinct centromeric repeats and a large number of B. nigra specific gene clusters that break the gene collinearity between the A and the B genomes. The genome assembly reported here will provide a fillip to the breeding work on oleiferous types of mustard that are grown extensively in the dry land areas of South Asia and elsewhere.

scholarly journals A New High-Quality Draft Genome Assembly of the Chinese Cordyceps Ophiocordyceps sinensis

2020 ◽  
Vol 12 (7) ◽  
pp. 1074-1079 ◽  
Author(s):  
Ruihao Shu ◽  
Jihong Zhang ◽  
Qian Meng ◽  
Huan Zhang ◽  
Guiling Zhou ◽  
...  
Keyword(s):  
Single Molecule ◽  
Genome Assembly ◽  
Draft Genome ◽  
Gene Clusters ◽  
Tibet Plateau ◽  
Protein Coding ◽  
Draft Genome Assembly ◽  
Ophiocordyceps Sinensis ◽  
Homologous Protein ◽  
Genome Features

Abstract Ophiocordyceps sinensis (Berk.) is an entomopathogenic fungus endemic to the Qinghai-Tibet Plateau. It parasitizes and mummifies the underground ghost moth larvae, then produces a fruiting body. The fungus-insect complex, called Chinese cordyceps or “DongChongXiaCao,” is not only a valuable traditional Chinese medicine, but also a major source of income for numerous Himalayan residents. Here, taking advantage of rapid advances in single-molecule sequencing, we assembled a highly contiguous genome assembly of O. sinensis. The assembly of 23 contigs was ∼110.8 Mb with a N50 length of 18.2 Mb. We used RNA-seq and homologous protein sequences to identify 8,916 protein-coding genes in the IOZ07 assembly. Moreover, 63 secondary metabolite gene clusters were identified in the improved assembly. The improved assembly and genome features described in this study will further inform the evolutionary study and resource utilization of Chinese cordyceps.

scholarly journals Pervasive hybridizations in the history of wheat relatives

2018 ◽  
Author(s):  
Sylvain Glémin ◽  
Celine Scornavacca ◽  
Jacques Dainat ◽  
Concetta Burgarella ◽  
Véronique Viader ◽  
...  
Keyword(s):  
Methodological Approach ◽  
Diploid Species ◽  
Phylogenomic Analysis ◽  
D Genome ◽  
Species Relationship ◽  
B Genome ◽  
Hybridization Event ◽  
A Genome ◽  
History Of ◽  
Complex Scenario

AbstractBread wheat and durum wheat derive from an intricate evolutionary history of three genomes, namely A, B and D, present in both extent diploid and polyploid species. Despite its importance for wheat research, no consensus on the phylogeny of the wheat clade has emerged so far, possibly because of hybridizations and gene flows that make phylogeny reconstruction challenging. Recently, it has been proposed that the D genome originated from an ancient hybridization event between the A and B genomes1. However, the study only relied on four diploid wheat relatives when 13 species are accessible. Using transcriptome data from all diploid species and a new methodological approach, we provide the first comprehensive phylogenomic analysis of this group. Our analysis reveals that most species belong to the D-genome lineage and descend from the previously detected hybridization event, but with a more complex scenario and with a different parent than previously thought. If we confirmed that one parent was the A genome, we found that the second was not the B genome but the ancestor of Aegilops mutica (T genome), an overlooked wild species. We also unravel evidence of other massive gene flow events that could explain long-standing controversies in the classification of wheat relatives. We anticipate that these results will strongly affect future wheat research by providing a robust evolutionary framework and refocusing interest on understudied species. The new method we proposed should also be pivotal for further methodological developments to reconstruct species relationship with multiple hybridizations.

scholarly journals Insights on the process of reciprocal gene loss in the duplicate DPL genes of rice

2019 ◽  
Author(s):  
Xun Xu ◽  
Song Ge ◽  
Fu-min Zhang
Keyword(s):  
Evolutionary History ◽  
Gene Loss ◽  
Diploid Species ◽  
Recent Common Ancestor ◽  
Duplicate Genes ◽  
Evolutionary Divergence ◽  
Dna Transposons ◽  
B Genome ◽  
A Genome ◽  
History Of

Abstract Background: Reciprocal gene loss (RGL) of duplicate genes is an important genetic resource of reproductive isolation, which is essential for speciation. In the past decades, various RGL patterns have been revealed, but RGL process is still poorly understood. The RGL of the duplicate DOPPELGANGER1 (DPL1) and DOPPELGANGER2 (DPL2) gene can lead to BDM-type hybrid incompatibility between two rice subspecies. The evolutionary history of the duplicate genes, including their origin and mechanism of duplication as well as their evolutionary divergence after the duplication, remains unclear. In this study, we investigated the evolutionary history of the duplicate genes for gaining insights into the process of RGL.Results: We reconstructed phylogenetic relationships of DPL copies from all 15 diploid species representing six genome types of rice genus and then found that all the DPL copies from the latest diverged A- and B-genome gather into one monophyletic clade. Southern blot analysis also detected definitely two DPL copies only in A- and B-genome. High conserved collinearity can be observed between A- and B-genomic segments containing DPL1 and DPL2 respectively but not between DPL1 and DPL2 segments. Investigations of transposon elements indicated that DPL duplication is related to DNA transposons. Likelihood-based analyses with branch models showed a relaxation of selective constraint in DPL1 lineage but an enhancement in DPL2 lineage after DPL duplication. Sequence analysis also indicated that quite a few defective DPL1 can be found in 6 wild and cultivated species out of all 8 species of A-genome but only one defective DPL2 occurs in a cultivated rice subspecies. Conclusions: DPL duplication of rice originated in the recent common ancestor of A- and B-genome about 6.76 million years ago and the duplication was possibly caused by DNA transposons. The DPL1 is a redundant copy and has being in the process of pseudogenization, suggesting that artificial selection may play an important role in forming the RGL of DPLs between two rice subspecies during the domestication.

scholarly journals A high-quality genome assembly for the endangered golden snub-nosed monkey (Rhinopithecus roxellana)

GigaScience ◽  
2019 ◽  
Vol 8 (8) ◽  
Author(s):  
Lu Wang ◽  
Jinwei Wu ◽  
Xiaomei Liu ◽  
Dandan Di ◽  
Yuhong Liang ◽  
...  
Keyword(s):  
Single Molecule ◽  
Genome Assembly ◽  
Gene Families ◽  
Rhinopithecus Roxellana ◽  
High Quality ◽  
Chromosome Conformation ◽  
Protein Coding ◽  
A Genome ◽  
Close Relationship ◽  
High Quality Genome

Abstract Background The golden snub-nosed monkey (Rhinopithecus roxellana) is an endangered colobine species endemic to China, which has several distinct traits including a unique social structure. Although a genome assembly for R. roxellana is available, it is incomplete and fragmented because it was constructed using short-read sequencing technology. Thus, important information such as genome structural variation and repeat sequences may be absent. Findings To obtain a high-quality chromosomal assembly for R. roxellana qinlingensis, we used 5 methods: Pacific Bioscience single-molecule real-time sequencing, Illumina paired-end sequencing, BioNano optical maps, 10X Genomics link-reads, and high-throughput chromosome conformation capture. The assembled genome was ∼3.04 Gb, with a contig N50 of 5.72 Mb and a scaffold N50 of 144.56 Mb. This represented a 100-fold improvement over the previously published genome. In the new genome, 22,497 protein-coding genes were predicted, of which 22,053 were functionally annotated. Gene family analysis showed that 993 and 2,745 gene families were expanded and contracted, respectively. The reconstructed phylogeny recovered a close relationship between R. rollexana and Macaca mulatta, and these 2 species diverged ∼13.4 million years ago. Conclusion We constructed a high-quality genome assembly of the Qinling golden snub-nosed monkey; it had superior continuity and accuracy, which might be useful for future genetic studies in this species and as a new standard reference genome for colobine primates. In addition, the updated genome assembly might improve our understanding of this species and could assist conservation efforts.

scholarly journals SCAR Marker for the A Genome of Bananas (Musa spp. L.) Supports Lack of Differentiation between the A and B Genomes

2017 ◽  
Vol 9 (6) ◽  
pp. 64
Author(s):  
Lloyd Mabonga ◽  
Michael Pillay
Keyword(s):  
Scar Marker ◽  
Agronomic Traits ◽  
Random Amplified Polymorphic Dna ◽  
Diploid Species ◽  
Specific Marker ◽  
Correct Identification ◽  
Musa Spp ◽  
B Genome ◽  
A Genome ◽  
Putative Marker

  Bananas (Musa spp. L.) are grouped on the basis of their genomic origins in relation to Musa acuminata (A genome) and M. balbisiana (B genome). The two ancestral wild seeded diploid species evolved in vastly different geographical areas and contributed several agronomic traits towards the present genetic composition of cultivated bananas. Most cultivated bananas are triploid (AAA, AAB and ABB), some are diploid (AA, BB and AB) and a few are tetraploids (AAAA, AAAB, AABB and ABBB). Limitations on the correct identification of the A and B genomes in Musa have generated need for the development of new and more reliable techniques. Distinguishing the A and the B genome remains practically and theoretically important for banana breeders. The aim of the research was to develop a DNA based A genome specific marker for the identification of the A genome in bananas. A putative marker (600 bp) specific to the A genome was identified by Random Amplified Polymorphic DNA (RAPD) technique. A sequence characterised amplified region (SCAR) marker was developed from the RAPD amplicon. The SCAR primers annealed a 500 bp fragment specific to the A genome in a sample of 22 randomly selected homo- and heterogenomic A genome containing accessions representing different genome combinations. The 500 bp SCAR marker is useful for the identification of the A genome. However an additional 700 bp fragment annealed in all M. balbisiana genotypes and in five of the eight heterogenomic accessions, suggesting lack of differentiation between the A and B genome. This study has provided a 500 bp A genome SCAR marker and recent evidence that the A and B genomes of banana may not be as differentiated as previously considered.

scholarly journals Chromosome painting in cultivated banana and their wild relatives (Musa spp.) reveals differences in chromosome structure

2020 ◽  
Author(s):  
D Šimoníková ◽  
A Němečková ◽  
J Čížková ◽  
A Brown ◽  
R Swennen ◽  
...  
Keyword(s):  
Chromosome Structure ◽  
Diploid Species ◽  
Musa Acuminata ◽  
Cross Hybridization ◽  
B Genome ◽  
A Genome ◽  
Structural Chromosome ◽  
Cytogenetic Characterization ◽  
Hybrid Clones ◽  
Painting Probes

AbstractEdible banana cultivars are diploid, triploid or tetraploid hybrids which originated by natural cross hybridization between subspecies of diploid Musa acuminata, or between M. acuminata and diploid M. balbisiana. Participation of two other wild diploid species M. schizocarpa and M. textilis was also indicated by molecular studies. Fusion of gametes with structurally different chromosome sets may give rise to progenies with structural chromosome heterozygosity and reduced fertility due to aberrant chromosome pairing and unbalanced chromosome segregation. Only a few translocations have been classified on the genomic level so far and a comprehensive molecular cytogenetic characterization of cultivars and species of the family Musaceae is still lacking. FISH with chromosome-arm specific oligo painting probes was used for comparative karyotype analysis in a set of wild Musa species and edible banana clones. The results revealed large differences in chromosome structure discriminating individual accessions. These results permitted identification of putative progenitors of cultivated clones and clarified genomic constitution and evolution of aneuploid banana clones, which seem to be common among the polyploid banana accessions. New insights into the chromosome organization and structural chromosome changes will be a valuable asset in breeding programs, particularly in selection of appropriate parents for cross hybridization.HighlightOligo painting FISH revealed chromosomal translocations in subspecies of Musa acuminata (A genome), their intra-specific hybrids as well as in M. balbisiana (B genome) and in interspecific hybrid clones originating from cross hybridization between M. acuminata and M. balbisiana

scholarly journals Aligning optical maps to de Bruijn graphs

2019 ◽  
Vol 35 (18) ◽  
pp. 3250-3256 ◽  
Author(s):  
Kingshuk Mukherjee ◽  
Bahar Alipanahi ◽  
Tamer Kahveci ◽  
Leena Salmela ◽  
Christina Boucher
Keyword(s):  
Single Molecule ◽  
Genome Assembly ◽  
Sequence Data ◽  
Supplementary Information ◽  
De Bruijn Graph ◽  
Structural Variations ◽  
Regular Feature ◽  
A Genome ◽  
De Bruijn ◽  
Optical Maps

Abstract Motivation Optical maps are high-resolution restriction maps (Rmaps) that give a unique numeric representation to a genome. Used in concert with sequence reads, they provide a useful tool for genome assembly and for discovering structural variations and rearrangements. Although they have been a regular feature of modern genome assembly projects, optical maps have been mainly used in post-processing step and not in the genome assembly process itself. Several methods have been proposed for pairwise alignment of single molecule optical maps—called Rmaps, or for aligning optical maps to assembled reads. However, the problem of aligning an Rmap to a graph representing the sequence data of the same genome has not been studied before. Such an alignment provides a mapping between two sets of data: optical maps and sequence data which will facilitate the usage of optical maps in the sequence assembly step itself. Results We define the problem of aligning an Rmap to a de Bruijn graph and present the first algorithm for solving this problem which is based on a seed-and-extend approach. We demonstrate that our method is capable of aligning 73% of Rmaps generated from the Escherichia coli genome to the de Bruijn graph constructed from short reads generated from the same genome. We validate the alignments and show that our method achieves an accuracy of 99.6%. We also show that our method scales to larger genomes. In particular, we show that 76% of Rmaps can be aligned to the de Bruijn graph in the case of human data. Availability and implementation The software for aligning optical maps to de Bruijn graph, omGraph is written in C++ and is publicly available under GNU General Public License at https://github.com/kingufl/omGraph. Supplementary information Supplementary data are available at Bioinformatics online.

scholarly journals Characterization and analysis of the transcriptome in Arapaima gigas using multi-tissue RNA-sequencing

2020 ◽  
Author(s):  
Danilo L. Martins ◽  
Leonardo R. S. Campos ◽  
André M. Ribeiro-dos-Santos ◽  
Ana Carolina M. F. Coelho ◽  
Renata L. Dantas ◽  
...  
Keyword(s):  
Rna Sequencing ◽  
Expression Patterns ◽  
Gene Clusters ◽  
Molecular Networks ◽  
Specific Gene ◽  
Protein Coding ◽  
Tissue Specific ◽  
Functional Studies ◽  
A Genome ◽  
Arapaima Gigas

AbstractArapaima gigas is a giant bony tongue air-breathing fish, and a promising species for aquaculture due to its particular features. However, there is still a lack of information on its biology and few transcriptome studies are available. Our aim was to characterize the transcriptome of arapaima in order to shed light on molecular networks contributing to its unique traits. Through RNA-sequencing, we generated a transcriptome from eight tissues (brain, pituitary, heart, muscle, kidney, lung, ovary, and testis) collected from arapaima adults specimens. Using a genome-guided strategy associated with homologous protein evidence, 57,706 transcripts were assembled, which aligned to 23,353 high confidence protein-coding genes. The analysis revealed a global view of expression patterns, as well as it allowed us to identify tissue-specific gene clusters, transcription factors within the clusters, and to compare expression patterns between male and female. These analyses has generated tissue-specific and sex-biased transcriptome profiles, which will be helpful to understand its molecular biology, evolution, and also guide future functional studies of the arapaima.

scholarly journals Cryptocurrencies and Zero Mode Wave guides: An unclouded path to a more contiguous Cannabis sativa L. genome assembly.

2018 ◽  
Author(s):  
Kevin McKernan ◽  
Yvonne Helbert ◽  
Liam T. Kane ◽  
Heather Ebling ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Single Molecule ◽  
Genome Assembly ◽  
Cannabis Sativa ◽  
Zero Mode ◽  
Gene Clusters ◽  
Type Ii ◽  
Single Molecule Sequencing ◽  
Combined Use ◽  
Wave Guides ◽  
Repeat Expansions

We describe the use of a Decentralized Autonomous Organization (DAO) to crypto-fund the single molecule sequencing and publication of a Type II Cannabis plant. This resulted in the construction of the most contiguous Cannabis genome assembly to date. The combined use of the Dash cryptocurrency, DAOs, and Pacific Biosciences sequencing delivered a 1.03 Gb genome with a N50 of 665Kb in 77 days from funding to public upload. This represents a 230 fold improvement in the contiguity of the first cannabis assemblies in 2011 and a 4 fold improvement over all cannabis assemblies to date. 34Gb of additional sequencing pushed the assembly to a N50 of 3.8Mb. Hi-C data from Phase Genomics further scaffolded the assembly to 35 contigs at an N50 of 74Mb but requires additional curation. The genome is partially phased and larger than previously reported (2N = 1.33Gb). The CBCA, THCA and CBDA synthase gene clusters have been phased onto respective contigs demonstrating tandem repeat expansions.

scholarly journals A chromosomal-level genome assembly and the diet habit-specific amino acid mutation identification of the Cyprinidae fish Ancherythroculter nigrocauda

2020 ◽  
Author(s):  
Yanhong Sun ◽  
Guiying Wang ◽  
Jianfang Gui ◽  
Jian Chen ◽  
Pei Li ◽  
...  
Keyword(s):  
Amino Acid ◽  
Single Molecule ◽  
Genome Assembly ◽  
High Efficiency ◽  
Expression Patterns ◽  
Amino Acid Mutation ◽  
Specific Amino Acid ◽  
Genetic Breeding ◽  
A Genome ◽  
Chromosome Level

Abstract Background Ancherythroculter nigrocauda is an endemic Cyprinidae fish in China, it has many desirable traits for genetic breeding, including strong disease resistance, unusual stress tolerance and high efficiency in nutrition update, which have made it an emerging commercial aquaculture fish. With the publication of its close-related species’ genome sequence, we can study the diet-specific genomic mutations within Cyprinidae. Results Here we report whole genome assembly of a female A. nigrocauda individual constructed using the single molecule DNA sequencing platform PacBio Sequel. With the help of Hi-C anchoring, we successfully placed contigs to chromosome level (2n = 48), yielding a genome size of 1054.05 Mb with contig N50 of 3.40 Mb and scaffold N50 of 42.68 Mb. This genome assembly, which has reached a high base-level accuracy of 99.999%, harboring 33,606 annotated protein-coding genes. We also found 582 genes hold diet-specific amino acid mutation between herbivorous and carnivorous fishes and 26 of them showed significant different expression patterns in liver tissue of these two types of fishes. Conclusions The availability of the chromosome-level genome assembly of A. nigrocauda provides valuable resources for future in-depth comparative genomics studies and applications including genetic breeding. The diet-specific amino acid mutation can be used in breeding of new strains of carnivorous fishes which feed on herbivorous fodder.

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