High-quality Genome Research Articles

Haplotype-resolved genome and population genomics of the threatened garden dormouse in Europe

Genomic resources are important for evaluating genetic diversity and supporting conservation efforts. The garden dormouse (Eliomys quercinus) is a small rodent that has experienced one of the most severe modern population declines in Europe. We present a high-quality haplotype-resolved reference genome for the garden dormouse, and combine comprehensive short and long-read transcriptomics data sets with homology-based methods to generate a highly complete gene annotation. Demographic history analysis of the genome reveal a sharp population decline since the last interglacial, indicating an association between colder climates and population declines before anthropogenic influence. Using our genome and genetic data from 100 individuals, largely sampled in a citizen-science project across the contemporary range, we conduct the first population genomic analysis for this species. We find clear evidence for population structure across the species’ core Central European range. Notably, our data show that the Alpine population, characterized by strong differentiation and reduced genetic diversity, is reproductively isolated from other regions and likely represents a differentiated evolutionary significant unit (ESU). The predominantly declining Eastern European populations also show signs of recent isolation, a pattern consistent with a range expansion from Western to Eastern Europe during the Holocene, leaving relict populations now facing local extinction. Overall, our findings suggest that garden dormouse conservation may be enhanced in Europe through the designation of ESUs.

Genome assembly at chromosome scale with telomere ends for Pearlspot, Etroplus suratensis

AbstractThe pearlspot, Etroplus suratensis is a climate resilient cichlid fish that exhibits unusual adaptation to salinity. The fish is able to complete full life cycle in diverse salinity habitats ranging from fresh water to marine environments. High-quality primary and phased genome assemblies were generated for pearlspot fish using PacBio HiFi and Arima HiC sequencing technologies, for the first time. The primary assembly is highly contiguous with contig N50 length of 36 Mb. The final assembly is of 1.247 Gb with N50 length of 51.57 Mb and 98% of the genome length anchored to 24 chromosomes. The genome was assessed to be 99.9% complete based on BUSCO evaluation and was predicted to contain 52.96% repeat elements. We have predicted 27,192 protein encoding genes, of which 21,580 were functionally annotated. The genome offers an invaluable resource to understand adaptation of pearlspot fish to diverse salinity habitats.

MolluscDB 2.0: a comprehensive functional and evolutionary genomics database for over 1400 molluscan species

Abstract Mollusca represents the second-largest animal phylum but remains less explored genomically. The increase in high-quality genomes and diverse functional genomic data holds great promise for advancing our understanding of molluscan biology and evolution. To address the opportunities and challenges facing the molluscan research community in managing vast multi-omics resources, we developed MolluscDB 2.0 (http://mgbase.qnlm.ac), which integrates extensive functional genomic data and offers user-friendly tools for multilevel integrative and comparative analyses. MolluscDB 2.0 covers 1450 species across all eight molluscan classes and compiles ∼4200 datasets, making it the most comprehensive multi-omics resource for molluscs to date. MolluscDB 2.0 expands the layers of multi-omics data, including genomes, bulk transcriptomes, single-cell transcriptomes, proteomes, epigenomes and metagenomes. MolluscDB 2.0 also more than doubles the number of functional modules and analytical tools, updating 14 original modules and introducing 20 new, specialized modules. Overall, MolluscDB 2.0 provides highly valuable, open-access multi-omics platform for the molluscan research community, expediting scientific discoveries and deepening our understanding of molluscan biology and evolution.

Genomic surveillance of SARS-CoV-2 in Nepal

ABSTRACT During the COVID-19 pandemic, Nepal, like other countries, faced emerging SARS-CoV-2 variants. To evaluate the circulating variants, 278 samples collected between September 2021 and March 2022 were sequenced in the country. From these, 229 high-quality genomes were obtained (82.97% Omicron and 17.03% Delta) highlighting the genomic diversity of SARS-CoV-2 in Nepal.

Matching excellence: Oxford Nanopore Technologies’ rise to parity with Pacific Biosciences in genome reconstruction of non-model bacterium with high G+C content

The reconstruction of complete bacterial genomes is essential for microbial research, offering insights into genetic content, ontology and regulation. While Pacific Biosciences (PacBio) provides high-quality genomes, its cost remains a limitation. Oxford Nanopore Technologies (ONT) offers long reads at a lower cost, yet its error rate raises scepticism. Recent ONT advancements, such as new Flow cells (R10.4.1), chemistry (V14) and duplex mode, improve data quality. Our study compares ONT with PacBio and Illumina, including hybrid data. We used Propionibacterium freudenreichii, a bacterium with a genome known for being difficult to reconstruct. By combining data from ONT’s Native Barcoding and a custom-developed BARSEQ method, we achieved high-quality, near-perfect genome assemblies. Our findings demonstrate, for the first time, that the combination of nanopore-only long-native with shorter PCR DNA reads (~3 kb) results in high-quality genome reconstruction, comparable to hybrid data assembly from two sequencing platforms. This endorses ONT as a cost-effective, stand-alone strategy for bacterial genome reconstruction. Additionally, we compared methylated motif detection between PacBio and ONT R10.4.1 data, showing that results comparable to PacBio are achievable using ONT, especially when utilizing the advanced Nanomotif tool.

NCBI RefSeq: reference sequence standards through 25 years of curation and annotation

Abstract Reference sequences and annotations serve as the foundation for many lines of research today, from organism and sequence identification to providing a core description of the genes, transcripts and proteins found in an organism's genome. Interpretation of data including transcriptomics, proteomics, sequence variation and comparative analyses based on reference gene annotations informs our understanding of gene function and possible disease mechanisms, leading to new biomedical discoveries. The Reference Sequence (RefSeq) resource created at the National Center for Biotechnology Information (NCBI) leverages both automatic processes and expert curation to create a robust set of reference sequences of genomic, transcript and protein data spanning the tree of life. RefSeq continues to refine its annotation and quality control processes and utilize better quality genomes resulting from advances in sequencing technologies as well as RNA-Seq data to produce high-quality annotated genomes, ortholog predictions across more organisms and other products that are easily accessible through multiple NCBI resources. This report summarizes the current status of the eukaryotic, prokaryotic and viral RefSeq resources, with a focus on eukaryotic annotation, the increase in taxonomic representation and the effect it will have on comparative genomics. The RefSeq resource is publicly accessible at https://www.ncbi.nlm.nih.gov/refseq.

Deciphering the complex organelle genomes of two Rhododendron species and insights into adaptive evolution patterns in high-altitude

BackgroundThe genomes within organelles are crucial for physiological functions such as respiration and photosynthesis and may also contribute to environmental adaptation. However, the limited availability of genetic resources, particularly mitochondrial genomes, poses significant challenges for in-depth investigations.ResultsHere, we explored various assembly methodologies and successfully reconstructed the complex organelle genomes of two Rhododendron species: Rhododendron nivale subsp. boreale and Rhododendron vialii. The mitogenomes of these species exhibit various conformations, as evidenced by long-reads mapping. Notably, only the mitogenome of R. vialii can be depicted as a singular circular molecule. The plastomes of both species conform to the typical quadripartite structure but exhibit elongated inverted repeat (IR) regions. Compared to the high similarity between plastomes, the mitogenomes display more obvious differences in structure, repeat sequences, and codon usage. Based on the analysis of 58 organelle genomes from angiosperms inhabiting various altitudes, we inferred the genetic adaptations associated with high-altitude environments. Phylogenetic analysis revealed partial inconsistencies between plastome- and mitogenome-derived phylogenies. Additionally, evolutionary lineage was determined to exert a greater influence on codon usage than altitude. Importantly, genes such as atp4, atp9, mttB, and clpP exhibited signs of positive selection in several high-altitude species, suggesting a potential link to alpine adaptation.ConclusionsWe tested the effectiveness of different organelle assembly methods for dealing with complex genomes, while also providing and validating high-quality organelle genomes of two Rhododendron species. Additionally, we hypothesized potential strategies for high-altitude adaptation of organelles. These findings offer a reference for the assembly of complex organelle genomes, while also providing new insights and valuable resources for understanding their adaptive evolution patterns.

Soil metagenomics reveals reduced tillage improves soil functional profiles of carbon, nitrogen, and phosphorus cycling in bulk and rhizosphere soils

Conservation tillage practices (CAT) are known to benefit soil health and soil ecosystem functions relative to conventional tillage (CVT); however, much uncertainty remains concerning microbial functional traits and their subsequent effects on soil nutrients under different tillage practices. We analyzed the functional profiles of the C, N, and P cycles in response to CAT of no-tillage (NT), reduced tillage (RT), and CVT of moldboard plowing (MP) in bulk and rhizosphere soils using shotgun sequencing. CAT induced distinct microbial functional patterns relative to CVT, and these differences were generally more evident in rhizosphere soils than in bulk soils. CAT promotes multiple metabolic pathways such as C and N decomposition, fermentation, CO oxidation, N fixation, nitrate reduction and inorganic-P and organic-P transformations in bulk and/or rhizosphere soils. Variations in these metabolic pathways were mainly driven by Bradyrhizobium, Mesorhizobium, Nitrososphaera, Phenylobacterium, Rhizobium which are affiliated with Proteobacteria, Actinobacteria, Acidobacteria, Bacteroidota and Thaumarchaeota. Furthermore, 24 high-quality metagenome-assembled genomes (MAGs) were reconstructed, of which three novel MAGs (TL100, TL46, and TL57) harbored functional genes regulating all metabolic pathways. In particular, NT-enriched MAGs (such as Sphingomonas) promote fermentation, resulting in the reduction of soil total carbon (TC) relative to MP in bulk soils. RT retained the contents of soil TC and total nitrogen (TN) well and up-regulated the phoR gene carried by Streptomyces, which promoted the regulation of P-starvation concomitantly with the increase in the contents of total phosphorous (TP) and available phosphorous (AP) in bulk soil. Additionally, assimilatory nitrate reduction coupled with organic-P mineralization was facilitated by CAT in rhizosphere soil, leading to the mitigation of N loss and the activation of soil organic-P for crop uptake. Overall, our results revealed that CAT significantly accelerated multiple metabolic potentials, and RT could sustain soil nutrient contents better than NT.

Verrucomicrobia of the Family Chthoniobacteraceae Participate in Xylan Degradation in Boreal Peat Soils

The phylum Verrucomicrobiota is one of the main groups of soil prokaryotes, which remains poorly represented by cultivated organisms. The major recognized role of Verrucomicrobiota in soils is the degradation of plant-derived organic matter. These bacteria are particularly abundant in peatlands, where xylan-type hemicelluloses represent one of the most actively decomposed peat constituents. The aim of this work was to characterize the microorganisms capable of hydrolyzing xylan under the anoxic conditions typical of peatland soils. The laboratory incubation of peat samples with xylan resulted in the pronounced enrichment of several phylotypes affiliated with the Verrucomicrobiota, Firmicutes, and Alphaproteobacteria. Sequencing of the metagenome of the enrichment culture allowed us to recover high-quality metagenome-assembled genomes (MAGs) assigned to the genera Caproiciproducens, Clostridium, Bacillus (Firmicutes), and Rhizomicrobium (Alphaproteobacteria), Cellulomonas (Actinobacteriota) and the uncultured genus-level lineage of the family Chthoniobacteraceae (Verrucomicrobiota). The latter bacterium, designated “Candidatus Chthoniomicrobium xylanophilum” SH-KS-3, dominated in the metagenome and its MAG was assembled as a complete closed chromosome. An analysis of the SH-KS-3 genome revealed potential endo-1,4-beta-xylanases, as well as xylan beta-1,4-xylosidases and other enzymes involved in xylan utilization. A genome analysis revealed the absence of aerobic respiration and predicted chemoheterotrophic metabolism with the capacity to utilize various carbohydrates, including cellulose, and to perform fermentation or nitrate reduction. An analysis of other MAGs suggested that Clostridium and Rhizomicrobium could play the role of primary xylan degraders while other community members probably took advantage of the availability of xylo-oligosaccharides and xylose or utilized low molecular weight organics.

Uncovering the fungus responsible for stem and root rot of false indigo: pathogen identification, new disease description, and genome analyses.

Calonectria spp. can cause destructive diseases on forestry crops, legumes like soybean and peanut, and ornamentals. Species of Calonectria affecting ornamental plants are not well characterized or understood, though they have been widely documented as an issue in the ornamental industry. This research focused on the molecular identification, pathogenicity validation, and genome analysis of a Calonectria sp. isolate recovered from ornamental blue false indigo (Baptisia australis) plants showing disease symptoms of crown and root rot in a commercial nursery in Virginia. The fungus on B. australis was identified as C. fujianensis (Nectriaceae, Hypocreales), a member of the C. colhuonii species complex using multilocus sequencing. Pathogenicity tests were fulfilled by inoculating C. fujianensis conidia on B. australis seedlings, confirming a causal relationship between this pathogen and the disease symptoms observed. A 62.7 Mb high-quality hybrid genome assembly generated using Illumina and Nanopore data was obtained, contained in 16 contigs, four of which were complete chromosomes. A total of 750 effectors were found in the genome, similar to cutinase and pectinase virulence factors described from other Calonectria species' genomes. Characterization of this novel disease of B. australis advances our understanding of Calonectria as an important but poorly studied group of plant pathogens.

Large-scale metagenomic assembly provide new insights into the genetic evolution of gut microbiomes in plateau ungulates

Trillions of microbes colonize the ungulate gastrointestinal tract, playing a pivotal role in enhancing host nutrient utilization by breaking down cellulose and hemicellulose present in plants. Here, through large-scale metagenomic assembly, we established a catalog of 131,416 metagenome-assembled genomes (MAGs) and 11,175 high-quality species-level genome bins (SGBs) from 17 species of ungulates in China. Our study revealed the convergent evolution of high relative abundances of carbohydrate-active enzymes (CAZymes) in the gut microbiomes of plateau-dwelling ungulates. Notably, two significant factors contribute to this phenotype: structural variations in their gut microbiome genomes, which contain more CAZymes, and the presence of novel gut microbiota species, particularly those in the genus Cryptobacteroides, which are undergoing independent rapid evolution and speciation and have higher gene densities of CAZymes. Furthermore, these enrichment CAZymes in the gut microbiomes are highly enrichment in known metabolic pathways for short-chain fatty acid (SCFA) production. Our findings not only provide a valuable genomic resource for understanding the gut microbiomes of ungulates but also offer fresh insights into the interaction between gut microbiomes and their hosts, as well as the co-adaptation of hosts and their gut microbiomes to their environments.

Chromosome-level genome assembly of the ivory shell Babylonia areolata

The ivory shell Babylonia areolata is an economically important marine benthic gastropod known for its rapid growth and high nutritional value. B. areolata is distributed in Southeast Asia and the southeast coastal areas of China. In this study, we constructed a high-quality genome for B. areolata using PacBio, Illumina, and Hi-C sequencing technologies. The genome assembly comprised 35 chromosomal sequences with a total length of 1.65 Gb. The scaffold and contig N50 lengths were 53.17 Mb and 2.64 Mb, respectively, with repeat sequences constituting 64.46% of the genome. Furthermore, 26,130 protein-coding genes and 96.75% of the genome’s BUSCOs were identified. This inaugural report of a B. areolata genome provides crucial foundational information for further investigations into the biology, genomics, and genetic improvement of economic traits of this species.

Chromosome architecture as a determinant for biosynthetic diversity in Micromonospora.

Natural products - small molecules generated by organisms to facilitate ecological interactions - are of great importance to society and are used as antibacterial, antiviral, antifungal and anticancer drugs. However, the role and evolution of these molecules and the fitness benefits they provide to their hosts in their natural habitat remain an outstanding question. In bacteria, the genes that encode the biosynthetic proteins that generate these molecules are organised into discrete loci termed biosynthetic gene clusters (BGCs). In this work, we asked the following question: How are biosynthetic gene clusters organised at the chromosomal level? We sought to answer this using publicly available high-quality assemblies of Micromonospora, an actinomycete genus with members responsible for biosynthesizing notable natural products, such as gentamicin and calicheamicin. By orienting the Micromonospora chromosome around the origin of replication, we demonstrated that Micromonospora has a conserved origin-proximal region, which becomes progressively more disordered towards the antipodes of the origin. We then demonstrated through genome mining of these organisms that the conserved origin-proximal region and the origin-distal region of Micromonospora have distinct populations of BGCs and, in this regard, parallel the organization of Streptomyces, which possesses linear chromosomes. Specifically, the origin-proximal region contains highly syntenous, conserved BGCs predicted to biosynthesize terpenes and a type III polyketide synthase. In contrast, the ori-distal region contains a highly diverse population of BGCs, with many BGCs belonging to unique gene cluster families. These data highlight that genomic plasticity in Micromonospora is locus-specific, and highlight the importance of using high-quality genome assemblies for natural product discovery and guide future natural product discovery by highlighting that biosynthetic novelty may be enriched in specific chromosomal neighbourhoods.

Decoding the Genetic Code: Scientific Exploration of the Telomere-totelomere (T2T) Genome

Abstract: With the development of third-generation sequencing technology, genome assembly has entered a new era. The combination of multiple sequencing methods can combine the strengths of each, resulting in higher-quality assembly results. Telomere-to-Telomere (T2T) genome refers to a zero gap genome that is assembled at the T2T level of one or more chromosomes through the combination of multiple sequencing technologies, such as Pacific Biosciences High-Fidelity (PacBio HiFi), Oxford Nanopore Technologies (ONT) Ultra-long, High-throughput Chromosome Conformation Capture (Hi-C), and others. High-quality reference genomes are the basis for genomics research, and the T2T genome has enabled the exploration of unknown areas of the genome, such as telomeres and centromeres, which has provided a more in-depth direction for research. This review provides a comprehensive overview of the T2T genome, reviewing the development of sequencing technologies and then outlining sequencing strategies, assembly methods, quality assessment processes, and analysis software for the T2T genome with practical examples. Representative T2T genomic species of plants, animals, and microorganisms (e.g., human, Arabidopsis, brewer's yeast, and so on) are presented separately. A summary of the potential and challenges of current T2T genomic applications is provided, along with an outlook for future developments.

Chromosome-scale genome assembly of Codonopsis pilosula and comparative genomic analyses shed light on its genome evolution

IntroductionCodonopsis pilosula is a significant plant in traditional Chinese medicine, valued for its edible and medicinal properties. However, the lack of available genomic resources has hindered further research.MethodsThis study presents the first chromosome-scale genome assembly of C. pilosula using PacBio CLR reads and Hi-C scaffolding technology. Additionally, Ks analysis and syntenic depth analysis were performed to elucidate its evolutionary history.ResultsThe final assembly yielded a high-quality genome of 679.20 Mb, which was anchored to 8 pseudo-chromosomes with an anchoring rate of 96.5% and a scaffold N50 of 80.50 Mb. The genome assembly showed a high completeness of 97.6% based on Benchmarking with Universal Single-Copy Orthologs (BUSCO) analysis. Repetitive elements constituted approximately 76.8% of the genome, with long terminal repeat retrotransposons (LTRs) accounting for about 39.17%. Ks and syntenic depth analyses revealed that the polyploidization history of three platycodonoid clade species involved only the γ-WGT event. Karyotype evolutionary analysis identified an ancestral karyotype with 9 protochromosomes for the three platycodonoid clade species. Moreover, non-WGD genes, particularly those arising from tandem duplications, were found to contribute significantly to gene family expansion.DiscussionThese findings provide essential insights into the genetic diversity and evolutionary biology of C. pilosula, aiding its conservation and sustainable use.

Comparative genomic analysis and characterization of novel high-quality draft genomes from the coal metagenome.

Coal, a sedimentary rock harbours a complex microbial community that plays a significant role in its formation and characteristics. However, coal metagenome sequencing and studies were less, limiting our understanding of this complex ecosystem. This study aimed to reconstruct high-quality metagenome-assembled genomes (MAGs) from the coal sample collected in the Neyveli mine to explore the unrevealed diversity of the coal microbiome. Using Illumina sequencing, we obtained high-quality raw reads in FASTQ format. Subsequently, de novo assembly and binning with metaWRAP software facilitated the reconstruction of coal MAGs. Quality assessment using CheckM identified 10 High-Quality MAGs (HQ MAGs), 7 medium-quality MAGs (MQ MAGs), and 6 low-quality MAGs (LQ MAGs). Further analysis using GTDB-Tk revealed four HQ MAGs as known species like Dermacoccus abyssi, Sphingomonas aquatilis, Acinetobacter baumannii, and Burkholderia cenocepacia. The remaining six HQ MAGs were classified as Comamonas, Arthrobacter, Noviherbaspirillum, Acidovorax, Oxalicibacterium, and Bordetella and designated as novel genomes by the validation of digital DNA-DNA hybridization (dDDH). Phylogenetic analysis and further pangenome analysis across the phylogenetic groups revealed a similar pattern with a high proportion of cloud genes. We further analysed the functional potential of these MAGs and closely related genomes using COG. The comparative functional genomics revealed that novel genomes are highly versatile, potentially reflecting adaptations to the coal environment. BlastKOALA was used to conduct a detailed analysis of the metabolic pathways associated with the MAGs. This study highlights the comparative genomic analysis of novel coal genomes with their closely related genomes to understand the evolutionary relationships and functional properties.

MATEdb2, a Collection of High-Quality Metazoan Proteomes across the Animal Tree of Life to Speed Up Phylogenomic Studies

Abstract Recent advances in high-throughput sequencing have exponentially increased the number of genomic data available for animals (Metazoa) in the last decades, with high-quality chromosome-level genomes being published almost daily. Nevertheless, generating a new genome is not an easy task due to the high cost of genome sequencing, the high complexity of assembly, and the lack of standardized protocols for genome annotation. The lack of consensus in the annotation and publication of genome files hinders research by making researchers lose time in reformatting the files for their purposes but can also reduce the quality of the genetic repertoire for an evolutionary study. Thus, the use of transcriptomes obtained using the same pipeline as a proxy for the genetic content of species remains a valuable resource that is easier to obtain, cheaper, and more comparable than genomes. In a previous study, we presented the Metazoan Assemblies from Transcriptomic Ensembles database (MATEdb), a repository of high-quality transcriptomic and genomic data for the two most diverse animal phyla, Arthropoda and Mollusca. Here, we present the newest version of MATEdb (MATEdb2) that overcomes some of the previous limitations of our database: (i) we include data from all animal phyla where public data are available, and (ii) we provide gene annotations extracted from the original GFF genome files using the same pipeline. In total, we provide proteomes inferred from high-quality transcriptomic or genomic data for almost 1,000 animal species, including the longest isoforms, all isoforms, and functional annotation based on sequence homology and protein language models, as well as the embedding representations of the sequences. We believe this new version of MATEdb will accelerate research on animal phylogenomics while saving thousands of hours of computational work in a plea for open, greener, and collaborative science.

Genetic Variation in Jamaican Populations of the Coffee Berry Borer, Hypothenemus hampei.

The coffee berry borer (CBB) Hypothenemus hampei was first described in Africa in 1867 and has spread to all major coffee-producing regions worldwide, including Jamaica. Using long-read sequencing, we produced a new high-quality reference genome (172.7 Mb) for the Jamaican strain of the CBB, with 93% of the genome assembled into 14 scaffolds. Whole genome sequencing of pooled samples from different populations across Jamaica showed that the CBB harbors low levels of genetic diversity alongside an excess of low-frequency alleles, indicative of a recent genetic bottleneck. The analyses also showed a recent surge in the activity of transposable elements (TEs), particularly LINE/R1 and LTR/Gypsy elements, within CBB populations. Our findings offer first insights into the evolutionary genomics of CBB populations in Jamaica, highlighting the potential role of TEs in shaping the genome of this important pest species.

First Complete Genome Sequence of Nigrospora osmanthi: A Fundamental Resource for Studying the Plant Pathogenic Fungus

Nigrospora osmanthi strain Z1 is a potential bioherbicide for the biological control of water lettuce, one of the most common invasive weeds. Here, the first high-quality genome assembly of N. osmanthi was obtained by a combination of PacBio and Illumina sequencing technologies. Twelve contigs representing the nuclear genome and one mitochondrial DNA were generated, with a total length of 45.94 Mb, an N50 equal to 6.99 Mb, and a GC content of 57.91%; 9 of the 12 nuclear contigs represented chromosomes from telomere to telomere characterized by telomeric-like repeats. A total of 11,051 genes were predicted using a combination of gene prediction tools, including 336 noncoding RNAs, 1,298 genes encoding secretory proteins, 1,735 genes encoding carbohydrate-active enzymes, 1,955 fungal virulence factors, and 50 putative secondary metabolite gene clusters. This complete genome sequence can serve as a valuable resource for future comparative genomic studies of the fungus Nigrospora for effective application in the biocontrol of invasive species and the discovery of fungal secondary metabolites. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Genome sequencing and transcriptome analysis provide an insight into the hypoxia resistance of Channa asiatica

Channa asiatica is an economically valuable fish species and excellent model for studying hypoxic tolerance. However, the underlying genetic and molecular mechanisms are poorly understood. In this study, we assembled a high-quality C. asiatica genome (23 chromosomes, totaling 722 Mb) using a combination of Illumina short-read, PacBio long-read, and Hi-C sequencing. Repetitive elements accounted for 28.39%of the C. asiatica genome, and 23,949 protein-coding genes were predicted, with 96.63 % of these functionally annotated. Moreover, a comparative genomic analysis of 12 fish genomes showed that gene families associated with oxygen binding and transport were expanded in C. asiatica. In addition, transcriptome analysis revealed that multiple oxidative stress pathways were activated when C. asiatica was exposed to air. In conclusion, this study provided high-quality genome assembly and transcriptome data, both serving as critical resources for researching the genetic basis of hypoxic tolerance in C. asiatica.