scholarly journals Toward a genome sequence for every animal: Where are we now?

2021 ◽  
Vol 118 (52) ◽  
pp. e2109019118
Author(s):  
Scott Hotaling ◽  
Joanna L. Kelley ◽  
Paul B. Frandsen
Keyword(s):  
Assembly Quality ◽  
Genetic Database ◽  
Eukaryotic Diversity ◽  
Gene Annotations ◽  
A Genome ◽  
Long Read ◽  
Global Representation ◽  
Global North ◽  
Genomic Resource ◽  
Genome Assemblies

In less than 25 y, the field of animal genome science has transformed from a discipline seeking its first glimpses into genome sequences across the Tree of Life to a global enterprise with ambitions to sequence genomes for all of Earth’s eukaryotic diversity [H. A. Lewin et al., Proc. Natl. Acad. Sci. U.S.A. 115, 4325–4333 (2018)]. As the field rapidly moves forward, it is important to take stock of the progress that has been made to best inform the discipline’s future. In this Perspective, we provide a contemporary, quantitative overview of animal genome sequencing. We identified the best available genome assemblies in GenBank, the world’s most extensive genetic database, for 3,278 unique animal species across 24 phyla. We assessed taxonomic representation, assembly quality, and annotation status for major clades. We show that while tremendous taxonomic progress has occurred, stark disparities in genomic representation exist, highlighted by a systemic overrepresentation of vertebrates and underrepresentation of arthropods. In terms of assembly quality, long-read sequencing has dramatically improved contiguity, whereas gene annotations are available for just 34.3% of taxa. Furthermore, we show that animal genome science has diversified in recent years with an ever-expanding pool of researchers participating. However, the field still appears to be dominated by institutions in the Global North, which have been listed as the submitting institution for 77% of all assemblies. We conclude by offering recommendations for improving genomic resource availability and research value while also broadening global representation.

scholarly journals Towards a genome sequence for every animal: where are we now?

2021 ◽  
Author(s):  
Scott Hotaling ◽  
Joanna L Kelley ◽  
Paul B Frandsen
Keyword(s):  
Assembly Quality ◽  
Genetic Database ◽  
Eukaryotic Diversity ◽  
Gene Annotations ◽  
A Genome ◽  
Long Read ◽  
Global North ◽  
Genomic Resource ◽  
Average Gene ◽  
Genome Assemblies

In less than 25 years, the field of animal genome science has transformed from a discipline seeking its first glimpses into genome sequences across the Tree of Life to a global enterprise with ambitions to sequence genomes for all of Earth's eukaryotic diversity (1). As the field rapidly moves forward, it is important to take stock of the progress that has been made to best inform the discipline's future. In this perspective, we provide a contemporary, quantitative perspective on animal genome sequencing. We identified the best available genome assemblies on GenBank, the world's most extensive genetic database, for 3,278 unique animals across 24 phyla. We assessed taxonomic representation, assembly quality, and annotation status for major clades. We show that while tremendous taxonomic progress has occurred, stark disparities in genomic representation exist, highlighted by a systemic overrepresentation of vertebrates and underrepresentation of arthropods. In terms of assembly quality, long-read sequencing has dramatically improved contiguity and, on average, gene annotations are available for just 34.3% of taxa. Furthermore, we show that animal genome science has diversified in recent years with an ever-expanding pool of researchers participating. However, the field still appears to be dominated by institutions in the Global North, which have been listed as the submitting institution for 77% of all assemblies. We conclude by offering recommendations for how we can collectively improve genomic resource availability and value while also broadening representation worldwide.

scholarly journals Genome sequence resource of Phomopsis longicolla strain YC2-1, a fungal pathogen causing Phomopsis stem blight in soybean

2021 ◽  
Author(s):  
Xiaolin Zhao ◽  
Zhichao Zhang ◽  
Sujiao Zheng ◽  
Wenwu Ye ◽  
Xiaobo Zheng ◽  
...  
Keyword(s):  
Genome Assembly ◽  
Stem Canker ◽  
Quality Data ◽  
Phomopsis Longicolla ◽  
Protein Coding ◽  
Stem Blight ◽  
A Genome ◽  
Long Read ◽  
Genomic Resource ◽  
Blight Disease

Diaporthe-Phomopsis disease complex causes considerable yield losses in soybean production worldwide. As one of the major pathogens, Phomopsis longicolla T. W. Hobbs (syn. Diaporthe longicolla) is not only the primary agent of Phomopsis seed decay, but also one of the agents of Phomopsis pod and stem blight, and Phomopsis stem canker. We performed both PacBio long read sequencing and Illumina short read sequencing, and obtained a genome assembly for the P. longicolla strain YC2-1, which was isolated from soybean stem with Phomopsis stem blight disease. The 63.1 Mb genome assembly contains 87 scaffolds, with a minimum, maximum, and N50 scaffold length of 20 kb, 4.6 Mb, and 1.5 Mb respectively, and a total of 17,407 protein-coding genes. The high-quality data expand the genomic resource of P. longicolla species and will provide a solid foundation for a better understanding of their genetic diversity and pathogenic mechanisms.

scholarly journals Telomere-to-telomere gapless chromosomes of banana using nanopore sequencing

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Caroline Belser ◽  
Franc-Christophe Baurens ◽  
Benjamin Noel ◽  
Guillaume Martin ◽  
Corinne Cruaud ◽  
...  
Keyword(s):  
Musa Acuminata ◽  
Genetic Maps ◽  
Nanopore Sequencing ◽  
Genome Coverage ◽  
Long Reads ◽  
Oxford Nanopore ◽  
A Genome ◽  
Long Read ◽  
Genome Assemblies ◽  
First Time

AbstractLong-read technologies hold the promise to obtain more complete genome assemblies and to make them easier. Coupled with long-range technologies, they can reveal the architecture of complex regions, like centromeres or rDNA clusters. These technologies also make it possible to know the complete organization of chromosomes, which remained complicated before even when using genetic maps. However, generating a gapless and telomere-to-telomere assembly is still not trivial, and requires a combination of several technologies and the choice of suitable software. Here, we report a chromosome-scale assembly of a banana genome (Musa acuminata) generated using Oxford Nanopore long-reads. We generated a genome coverage of 177X from a single PromethION flowcell with near 17X with reads longer than 75 kbp. From the 11 chromosomes, 5 were entirely reconstructed in a single contig from telomere to telomere, revealing for the first time the content of complex regions like centromeres or clusters of paralogous genes.

scholarly journals Long-reads are revolutionizing 20 years of insect genome sequencing

2021 ◽  
Author(s):  
Scott Hotaling ◽  
John S. Sproul ◽  
Jacqueline Heckenhauer ◽  
Ashlyn Powell ◽  
Amanda M. Larracuente ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Nuclear Genome ◽  
Sequencing Technology ◽  
Assembly Quality ◽  
Insect Genome ◽  
Long Reads ◽  
Long Read ◽  
Field Perspective ◽  
Genome Assemblies ◽  
The Impact

The first insect genome (Drosophila melanogaster) was published two decades ago. Today, nuclear genome assemblies are available for a staggering 601 different insects representing 20 orders. Here, we analyzed the best assembly for each insect and provide a “state of the field” perspective, emphasizing taxonomic representation, assembly quality, gene completeness, and sequencing technology. We show that while genomic efforts have been biased towards specific groups (e.g., Diptera), assemblies are generally contiguous with gene regions intact. Most notable, however, has been the impact of long-read sequencing; assemblies that incorporate long-reads are ∼48x more contiguous than those that do not.

scholarly journals Major improvements to the Heliconius melpomene genome assembly used to confirm 10 chromosome fusion events in 6 million years of butterfly evolution

2015 ◽  
Author(s):  
John Davey ◽  
Mathieu Chouteau ◽  
Sarah L. Barker ◽  
Luana Maroja ◽  
Simon W. Baxter ◽  
...  
Keyword(s):  
Genome Assembly ◽  
Draft Genome ◽  
Chromosome Fusion ◽  
Short Read Sequencing ◽  
A Genome ◽  
Heliconius Melpomene ◽  
Long Read ◽  
In The Wild ◽  
Chromosome Fusions ◽  
Genome Assemblies

The Heliconius butterflies are a widely studied adaptive radiation of 46 species spread across Central and South America, several of which are known to hybridise in the wild. Here, we present a substantially improved assembly of the Heliconius melpomene genome, developed using novel methods that should be applicable to improving other genome assemblies produced using short read sequencing. Firstly, we whole genome sequenced a pedigree to produce a linkage map incorporating 99% of the genome. Secondly, we incorporated haplotype scaffolds extensively to produce a more complete haploid version of the draft genome. Thirdly, we incorporated ~20x coverage of Pacific Biosciences sequencing and scaffolded the haploid genome using an assembly of this long read sequence. These improvements result in a genome of 795 scaffolds, 275 Mb in length, with an L50 of 2.1 Mb, an N50 of 34 and with 99% of the genome placed and 84% anchored on chromosomes. We use the new genome assembly to confirm that the Heliconius genome underwent 10 chromosome fusions since the split with its sister genus Eueides, over a period of about 6 million years.

scholarly journals Telomere-to-telomere gapless chromosomes of banana using nanopore sequencing

2021 ◽  
Author(s):  
Caroline Belser ◽  
Franc-Christophe Baurens ◽  
Benjamin Noel ◽  
Guillaume Martin ◽  
Corinne Cruaud ◽  
...  
Keyword(s):  
Musa Acuminata ◽  
Genetic Maps ◽  
Nanopore Sequencing ◽  
Genome Coverage ◽  
Long Reads ◽  
Oxford Nanopore ◽  
A Genome ◽  
Long Read ◽  
Genome Assemblies ◽  
First Time

AbstractLong-read technologies hold the promise to obtain more complete genome assemblies and to make them easier. Coupled with long-range technologies, they can reveal the architecture of complex regions, like centromeres or rDNA clusters. These technologies also make it possible to know the complete organization of chromosomes, which remained complicated before even when using genetic maps. However, generating a gapless and telomere-to-telomere assembly is still not trivial, and requires a combination of several technologies and the choice of suitable software. Here, we report a chromosome-scale assembly of a banana genome (Musa acuminata) generated using Oxford Nanopore long-reads. We generated a genome coverage of 177X from a single PromethION flowcell with near 17X with reads longer than 75Kb. From the 11 chromosomes, 5 were entirely reconstructed in a single contig from telomere to telomere, revealing for the first time the content of complex regions like centromeres or clusters of paralogous genes.

scholarly journals Pathways to polar adaptation in fishes revealed by long-read sequencing

2021 ◽  
Author(s):  
Scott Hotaling ◽  
Thomas Desvignes ◽  
John S. Sproul ◽  
Luana S.F. Lins ◽  
Joanna L Kelley
Keyword(s):  
Genome Wide ◽  
A Genome ◽  
Cebidichthys Violaceus ◽  
Long Read ◽  
Wide Perspective ◽  
Element Activity ◽  
Genomic Regions ◽  
Genome Assemblies ◽  
Response To Environmental Change ◽  
Globally Distributed

Long-read sequencing is driving a new reality for genome science where highly contiguous assemblies can be produced efficiently with modest resources. Genome assemblies from long-read sequencing are particularly exciting for understanding the evolution of complex genomic regions that are often difficult to assemble. In this study, we leveraged long-read sequencing to generate a high-quality genome assembly for an Antarctic eelpout, Opthalmolycus amberensis, the first for the globally distributed family Zoarcidae. We used this assembly to understand how O. amberensis has adapted to the harsh Southern Ocean and compared it to another group of Antarctic fishes: the notothenioids. We showed that from a genome-wide perspective, selection has largely acted on different targets in eelpouts relative to notothenioids. However, we did find some overlap; in both groups, selection has acted on genes involved in membrane structure and DNA repair. We found evidence for historical shifts of transposable element activity in O. amberensis and other polar fishes, perhaps reflecting a response to environmental change. We were specifically interested in the evolution of two complex genomic regions known to underlie key adaptations to polar seas: hemoglobin and antifreeze proteins (AFPs). We observed unique evolution of the hemoglobin MN cluster in eelpouts and related fishes in the suborder Zoarcoidei relative to other teleosts. For AFPs, we identified the first species in the suborder with no evidence of afpIII sequences (Cebidichthys violaceus), potentially reflecting a lineage-specific loss of this gene cluster. Beyond polar fishes, our results highlight the power of long-read sequencing to understand genome evolution.

scholarly journals Quinoa genome assembly employing genomic variation for guided scaffolding

2021 ◽  
Author(s):  
Alexandrina Bodrug-Schepers ◽  
Nancy Stralis-Pavese ◽  
Hermann Buerstmayr ◽  
Juliane C. Dohm ◽  
Heinz Himmelbauer
Keyword(s):  
Genome Assembly ◽  
Chenopodium Quinoa ◽  
Genomic Variation ◽  
Valuable Resource ◽  
Sequencing Data ◽  
Genome Wide ◽  
A Genome ◽  
Long Read ◽  
Genome Assemblies ◽  
Haplotype Information

Abstract Key message We propose to use the natural variation between individuals of a population for genome assembly scaffolding. In today’s genome projects, multiple accessions get sequenced, leading to variant catalogs. Using such information to improve genome assemblies is attractive both cost-wise as well as scientifically, because the value of an assembly increases with its contiguity. We conclude that haplotype information is a valuable resource to group and order contigs toward the generation of pseudomolecules. Abstract Quinoa (Chenopodium quinoa) has been under cultivation in Latin America for more than 7500 years. Recently, quinoa has gained increasing attention due to its stress resistance and its nutritional value. We generated a novel quinoa genome assembly for the Bolivian accession CHEN125 using PacBio long-read sequencing data (assembly size 1.32 Gbp, initial N50 size 608 kbp). Next, we re-sequenced 50 quinoa accessions from Peru and Bolivia. This set of accessions differed at 4.4 million single-nucleotide variant (SNV) positions compared to CHEN125 (1.4 million SNV positions on average per accession). We show how to exploit variation in accessions that are distantly related to establish a genome-wide ordered set of contigs for guided scaffolding of a reference assembly. The method is based on detecting shared haplotypes and their expected continuity throughout the genome (i.e., the effect of linkage disequilibrium), as an extension of what is expected in mapping populations where only a few haplotypes are present. We test the approach using Arabidopsis thaliana data from different populations. After applying the method on our CHEN125 quinoa assembly we validated the results with mate-pairs, genetic markers, and another quinoa assembly originating from a Chilean cultivar. We show consistency between these information sources and the haplotype-based relations as determined by us and obtain an improved assembly with an N50 size of 1079 kbp and ordered contig groups of up to 39.7 Mbp. We conclude that haplotype information in distantly related individuals of the same species is a valuable resource to group and order contigs according to their adjacency in the genome toward the generation of pseudomolecules.

scholarly journals Hapo-G, haplotype-aware polishing of genome assemblies with accurate reads

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Jean-Marc Aury ◽  
Benjamin Istace
Keyword(s):  
Single Molecule ◽  
Direct Consequence ◽  
High Quality ◽  
Sequencing Errors ◽  
Coding Regions ◽  
Sequencing Technologies ◽  
Long Reads ◽  
Oxford Nanopore ◽  
Long Read ◽  
Genome Assemblies

Abstract Single-molecule sequencing technologies have recently been commercialized by Pacific Biosciences and Oxford Nanopore with the promise of sequencing long DNA fragments (kilobases to megabases order) and then, using efficient algorithms, provide high quality assemblies in terms of contiguity and completeness of repetitive regions. However, the error rate of long-read technologies is higher than that of short-read technologies. This has a direct consequence on the base quality of genome assemblies, particularly in coding regions where sequencing errors can disrupt the coding frame of genes. In the case of diploid genomes, the consensus of a given gene can be a mixture between the two haplotypes and can lead to premature stop codons. Several methods have been developed to polish genome assemblies using short reads and generally, they inspect the nucleotide one by one, and provide a correction for each nucleotide of the input assembly. As a result, these algorithms are not able to properly process diploid genomes and they typically switch from one haplotype to another. Herein we proposed Hapo-G (Haplotype-Aware Polishing Of Genomes), a new algorithm capable of incorporating phasing information from high-quality reads (short or long-reads) to polish genome assemblies and in particular assemblies of diploid and heterozygous genomes.

scholarly journals HapSolo: an optimization approach for removing secondary haplotigs during diploid genome assembly and scaffolding

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Edwin A. Solares ◽  
Yuan Tao ◽  
Anthony D. Long ◽  
Brandon S. Gaut
Keyword(s):  
Cost Function ◽  
Anopheles Funestus ◽  
Hill Climbing ◽  
Optimization Approach ◽  
Sequencing Technology ◽  
Genome Data ◽  
A Genome ◽  
Long Read ◽  
Downstream Analysis ◽  
The Cost

Abstract Background Despite marked recent improvements in long-read sequencing technology, the assembly of diploid genomes remains a difficult task. A major obstacle is distinguishing between alternative contigs that represent highly heterozygous regions. If primary and secondary contigs are not properly identified, the primary assembly will overrepresent both the size and complexity of the genome, which complicates downstream analysis such as scaffolding. Results Here we illustrate a new method, which we call HapSolo, that identifies secondary contigs and defines a primary assembly based on multiple pairwise contig alignment metrics. HapSolo evaluates candidate primary assemblies using BUSCO scores and then distinguishes among candidate assemblies using a cost function. The cost function can be defined by the user but by default considers the number of missing, duplicated and single BUSCO genes within the assembly. HapSolo performs hill climbing to minimize cost over thousands of candidate assemblies. We illustrate the performance of HapSolo on genome data from three species: the Chardonnay grape (Vitis vinifera), with a genome of 490 Mb, a mosquito (Anopheles funestus; 200 Mb) and the Thorny Skate (Amblyraja radiata; 2650 Mb). Conclusions HapSolo rapidly identified candidate assemblies that yield improvements in assembly metrics, including decreased genome size and improved N50 scores. Contig N50 scores improved by 35%, 9% and 9% for Chardonnay, mosquito and the thorny skate, respectively, relative to unreduced primary assemblies. The benefits of HapSolo were amplified by down-stream analyses, which we illustrated by scaffolding with Hi-C data. We found, for example, that prior to the application of HapSolo, only 52% of the Chardonnay genome was captured in the largest 19 scaffolds, corresponding to the number of chromosomes. After the application of HapSolo, this value increased to ~ 84%. The improvements for the mosquito’s largest three scaffolds, representing the number of chromosomes, were from 61 to 86%, and the improvement was even more pronounced for thorny skate. We compared the scaffolding results to assemblies that were based on PurgeDups for identifying secondary contigs, with generally superior results for HapSolo.

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