GenomeScope 2.0 and Smudgeplot for reference-free profiling of polyploid genomes

Phylogenomics provides new insight into the phylogeny and diversification of Asian Lappula (Boraginaceae)

The application of omics data serves as a powerful tool for investigating the roles of incomplete lineage sorting (ILS) and hybridization in shaping genomic diversity, offering deeper insights into complex evolutionary processes. In this study, we utilized deep genome sequencing data from 76 individuals of Lappula and its closely allied genera, collected from China and Central Asia. By employing the HybPiper and Easy353 pipelines, we recovered 262-279 single-copy nuclear genes (SCNs) and 352-353 Angiosperms353 genes, respectively. We analyzed multiple datasets, including complete chloroplast genomes and a filtered set of 475 SCNs, to conduct phylogenetic analyses using both concatenated and coalescent-based methods. Furthermore, we employed Quartet Sampling (QS), coalescent simulations, MSCquartets, HyDe, and reticulate network analyses to investigate the sources of phylogenetic discordance. Our results confirm that Lappula is polyphyletic, with L. mogoltavica clustering with Pseudolappula sinaica and forming a sister relationship with other taxa included in this study. Additionally, three Lepechiniella taxa nested within distinct clades of Lappula. Significant gene tree discordance was observed at several nodes within Lappula. Coalescent simulations and hybrid detection analyses suggest that both ILS and hybridization contribute to these discrepancies. Flow cytometry (FCM) analyses confirmed the presence of both diploid and tetraploid taxa within Lappula. Phylogenetic network analyses further revealed that Clades IV and VII likely originated through hybridization, with the tetraploids in Clade IV arising from two independent hybridization events. Additionally, the "ghost lineage" identified as sister to Lappula redowskii serves as one of the donors in allopolyploidization. In conclusion, our study provides new insights into the deep phylogenetic relationships of Asian Lappula and its closely allied genera, contributing to a more comprehensive understanding of the evolution and diversification of Lappula.

Construction of the super pan-genome for the genus Actinidia reveals structural variations linked to phenotypic diversity

Kiwifruits, belonging to the genus Actinidia, are acknowledged as one of the most successfully domesticated fruits in the twentieth century. Despite the rich wild resources and diverse phenotypes within this genus, insights into the genomic changes are still limited. Here, we conducted whole-genome sequencing on seven representative materials from highly diversified sections of Actinidia, leading to the assembly and annotation of 14 haplotype genomes with sizes spanning from 602.0 to 699.6 Mb. By compiling these haplotype genomes, we constructed a super pan-genome for the genus. We identified numerous structural variations (SVs, including variations in gene copy number) and highly diverged regions in these genomes. Notably, significant SV variability was observed within the intronic regions of the MED25 and TTG1 genes across different materials, suggesting their potential roles in influencing fruit size and trichome formation. Intriguingly, our findings indicated a high genetic divergence between two haplotype genomes, with one individual, tentatively named Actinidia × leiocacarpae, from sect. Leiocacarpae. This likely hybrid with a heterozygous genome exhibited notable genetic adaptations related to resistance against bacterial canker, particularly through the upregulation of the RPM1 gene, which contains a specific SV, after infection by Pseudomonas syringae pv. actinidiae. In addition, we also discussed the interlineage hybridizations and taxonomic treatments of the genus Actinidia. Overall, the comprehensive pan-genome constructed here, along with our findings, lays a foundation for examining genetic compositions and markers, particularly those related to SVs, to facilitate hybrid breeding aimed at developing desired phenotypes in kiwifruits.

Phylogenomic and morphological evidence supports the reinstatement of the bamboo genus Clavinodum from Oligostachyum (Poaceae: Bambusoideae)

One of the most intractable problems in bamboo systematics concerns the three-branched bamboos of tribe Arundinarieae (Poaceae: Bambusoideae), which are collectively characterized by having three branches per mid-culm node. Previous phylogenetic studies based on double-digest restriction-site associated DNA sequencing (ddRAD-seq) data confirmed that Oligostachyum, a member of this group, is non-monophyletic, and in particular that Oligostachyum oedogonatum is a problematic species deserving further attention, as it appears to be morphologically and phylogenetically distinct from the other three-branched bamboos. Here we aim to define and confirm the phylogenetic position of O. oedogonatum, by including representatives from across its geographic range. We also provide new insights into the overall phylogeny of the three-branched bamboos and closely related genera, using multiple phylogenomic datasets. While a plastid genome-based tree is very poorly supported, phylogenies inferred using two sets of conserved nuclear genes and single nucleotide polymorphism (SNP) data yield generally well-supported and congruent topologies using coalescent-based approaches. The tree inferred from the largest concatenated gene set is the most dissimilar to other inferences. The nuclear-based data sets all recover a major clade that includes all of the three-branched bamboos and four other genera, which can be distinguished from related taxa due to their possession of three stigmas per floret and leptomorph rhizomes. Notably, eight O. oedogonatum samples form a clade that is distantly related to other members of Oligostachyum, including the type species of the genus (Oligostachyum sulcatum). Population genetic approaches and multi-species coalescent-based analysis of the nuclear data sets imply that seven of these populations can be treated as a single species, O. oedogonatum, but that one population from Jinggangshan is likely an intergeneric hybrid between O. oedogonatum and Pleioblastus. Morphologically, O. oedogonatum differs from all other three-branched bamboos, in having strongly asymmetrically swollen supra-nodal ridges, a laterally compressed spikelet, and rachilla segments that disarticulate readily below fertile florets. Because of its morphological distinctiveness and molecular phylogenetic position, we propose that this taxon should be reinstated as Clavinodum oedogonatum. We provide a new description for this monotypic genus here.

Chromosome-level genome assembly and annotation of Gypsophila vaccaria

Gypsophila vaccaria Sm., a member of the Caryophyllaceae family, is known for its dry mature seeds, which are widely used in traditional Chinese medicine as "Wang Bu Liu Xing". This study presents a high-quality, chromosome-scale genome assembly of G. vaccaria, integrating Hi-C technology with PacBio and Illumina sequencing data. The final assembled genome measures 1.09 Gb in total length, with a contig N50 of 9.73 Mb and a scaffold N50 of 73.3 Mb, and complete benchmarking universal single-copy orthologs (BUSCO) for the genome and protein modes were 95.9% and 94.9%. Notably, 99.93% of the sequences are anchored to 15 pseudo-chromosomes. A total of 21,795 protein-coding genes were predicted, and repetitive elements were found to constitute 80.43% of the assembled genome. This chromosome-level genome assembly serves as an invaluable resource for future research, including functional genomics and molecular breeding of G. vaccaria.

Mapping-based genome size estimation

While the size of chromosomes can be measured under a microscope, obtaining the exact size of a genome remains a challenge. Biochemical methods and k-mer distribution-based approaches allow only estimations. An alternative approach to estimate the genome size based on high contiguity assemblies and read mappings is presented here. Analyses of Arabidopsis thaliana and Beta vulgaris data sets are presented to show the impact of different parameters. Oryza sativa, Brachypodium distachyon, Solanum lycopersicum, Vitis vinifera, and Zea mays were also analyzed to demonstrate the broad applicability of this approach. Further, MGSE was also used to analyze Escherichia coli, Saccharomyces cerevisiae, and Caenorhabditis elegans datasets to show its utility beyond plants. Mapping-based Genome Size Estimation (MGSE) and additional scripts are available on GitHub: https://github.com/bpucker/MGSE . MGSE predicts genome sizes based on short reads or long reads requiring a minimal coverage of 5-fold.

Repeatome diversity in sea anemone genomics (Cnidaria: Actiniaria) based on the Actiniaria-REPlib library

BACKGROUND

Genomic repetitive DNA sequences (Repeatomes, REPs) are widespread in eukaryotes, influencing biological form and function. In Cnidaria, an early-diverging animal lineage, these sequences remain largely uncharacterized. This study investigates sea anemone REPs (Cnidaria: Actiniaria) in a phylogenetic context. We sequenced and assembled de novo the genome of Actinostella flosculifera and analyzed a total of 38 nuclear genomes to create the first ActiniariaREP library (Actiniaria-REPlib). We compared Actiniaria-REPlib with Repbase and RepeatModeler2 libraries, and used dnaPipeTE to annotate REPs from genomic short-read datasets of 36 species for divergence landscapes.

RESULTS

Our study assembled and annotated the mitochondrial genomes, including 27 newly assembled ones. We re-annotated ~92% of the unknown sequences from the initial nuclear genome library, finding that 6.4-30.6% were DNA transposons, 2.1-11.6% retrotransposons, 1-28.4% tandem repeat sequences, and 1.2-7% unclassifiable sequences. Actiniaria-REPlib recovered 9.4x more REP sequences from actiniarian genomes than Dfam and 10.4x more than Repbase. It yielded 79,903 annotated TE consensus sequences (74,643 known, 5,260 unknown), compared to Dfam with 7,697 (3,742 known, 3,944 unknown) and Repbae (763 known).

CONCLUSIONS

Our study significantly enhances the characterization of sea anemone repetitive DNA, assembling mitochondrial genomes, re-annotating nuclear sequences, and identifying diverse repeat elements. Actiniaria-REPlib vastly outperforms existing databases, recovering significantly more REP sequences and providing a comprehensive resource for future genomic and evolutionary studies in Actiniaria.

Haplotype-resolved genomes provide insights into the origins and functional significance of genome diversity in bivalves

Bivalves are famed for exhibiting vast genetic diversity of poorly understood origins and functional significance. Through comparative genomics, we demonstrate that high genetic diversity in these invertebrates is not directly linked to genome size. Using oysters as a representative clade, we show that despite genome size reduction during evolution, these bivalves maintain remarkable genetic variability. By constructing a haplotype-resolved genome for Crassostrea sikamea, we identify widespread haplotype divergent sequences (HDSs), representing genomic regions unique to each haplotype. We show that HDSs are driven by transposable elements, playing a key role in creating and maintaining genetic diversity during oyster evolution. Comparisons of haplotype-resolved genomes across four bivalve orders uncover diverse HDS origins, highlighting a role in genetic innovation and expression regulation across broad timescales. Further analyses show that, in oysters, haplotype polymorphisms drive gene expression variation, which is likely to promote phenotypic plasticity and adaptation. These findings advance our understanding of the relationships among genome structure, diversity, and adaptability in a highly successful invertebrate group.

The unexplored diversity of rough-seeded lupins provides rich genomic resources and insights into lupin evolution

Lupin crops provide nutritious seeds as an excellent source of dietary protein. However, extensive genomic resources are needed for crop improvement, focusing on key traits such as nutritional value and climate resiliency, to ensure global food security based on sustainable and healthy diets for all. Such resources can be derived either from related lupin species or crop wild relatives, which represent a large and untapped source of genetic variation for crop improvement. Here, we report genome assemblies of the cross-compatible species Lupinus cosentinii (Mediterranean) and its pan-Saharan wild relative L. digitatus, which are well adapted to drought-prone environments and partially domesticated. We show that both species are tetraploids, and their repetitive DNA content differs considerably from that of the main lupin crops L. angustifolius and L. albus. We present the complex evolutionary process within the rough-seeded lupins as a species-based model involving polyploidization and rediploidization. Our data also provide the foundation for a systematic analysis of genomic diversity among lupin species to promote their exploitation for crop improvement and sustainable agriculture.

Genome of the enigmatic watering-pot shell and morphological adaptations for anchoring in sediment

BACKGROUND

In this study, we present the first chromosome-scale genome of Verpa penis (Linnaeus, 1758), and the first for the bivalve clade Anomalodesmata. The present study has two separate foci. Primarily, we provide the genetic resource to bridge further studies from genome to phenome and propose hypotheses to guide future empirical investigations. Secondarily, based on morphology, we outline a conceptual exploration to address their adaptation. Watering-pot shells have been called "the weirdest bivalves" for their fused tubular shell resembling the spout of a watering can. This adventitious tube arose twice convergently in clavagelloidean bivalves. However, previous literature has never provided a convincing adaptive pathway.

RESULTS

The genome assembly of V. penis was about 507 Mb, with contig N50 of 5.33 Mb, and has 96.5% of sequences anchored onto 19 pseudochromosomes. Phylogenomic analyses of this new genome in context of other bivalves confirms the placement for Anomalodesmata as sister to the clade Imparidentia. Contrary to expectations from its highly modified body plan, there is no evidence of chromosome reduction compared to the ancestral karyotype of heterodont bivalves (1 N = 19). Drawing on established principles from engineering as well as morphology, the thought experiment about the adventitious tube seeks to extend current understanding by exploring parallels with other built structures. A new hypothesis explains one possible interpretation of the adaptive significance of this body form: it is potentially structurally optimised for vertical stability in relatively soft sediments, with parallels to the engineering principles of a suction anchor.

CONCLUSIONS

While the conclusions presented here on morphological interpretations are theoretical, this serves as a foundation for further empirical validation and refinement. Our study offers new insights to a long-standing mystery in molluscan body forms and provides genomic resources that are relevant to understanding molluscan evolution, biomineralisation, and biomimetic design.

Chromosome-level genome assembly of the doctor fish (Garra rufa)

Garra rufa, or doctor fish, is a small cyprinid known for its high-temperature tolerance and its use in ichthyotherapy. Recently, this trait has gained interest as a model for human diseases, including infections and cancer xenografts, though limited genomic resources hinder experimental use. In this study, we have generated a high-quality, chromosome-level genome assembly of G. rufa using PacBio HiFi long-read sequencing and Hi-C technology. The genome is 1.38 Gb in size, with 25 chromosomes and a scaffold N50 of 49.3 Mb. Approximately 59% of the genome consists of repetitive elements, while 27,352 protein-coding genes were annotated, with 98.3% being functionally characterized. BUSCO analysis revealed 94.5% and 94.7% completeness for the genome assembly and annotated protein sequences, respectively. Notably, we identified two heat shock transcription factor (HSF) genes, 239 heat shock protein (HSP)-related genes, and 1,036 heat shock elements (HSEs) in regulatory regions. Phylogenetic analysis supports the placement of G. rufa within the Labeoninae subfamily. This genome assembly provides a valuable resource for advancing G. rufa as a model organism.

Occurrence of aneuploidy across the range of coast redwood (Sequoia sempervirens)

Aneuploidy, a condition characterized by an abnormal number of chromosomes, can have significant consequences for fitness of an organism, often manifesting in reduced fertility and other developmental challenges. In plants, aneuploidy is particularly complex to study, especially in polyploid species such as coast redwood (Sequoia sempervirens (D. Don) Endl.), which is a hexaploid conifer (2n=6×=66). This study leverages a novel Markov Chain Monte Carlo method based on sequence depth to investigate the occurrence of aneuploidy across the range of coast redwood. We show that aneuploidy, defined here as a whole-chromosome gain or loss, is prevalent in second-growth redwoods, predominantly as additional chromosomes, while vegetatively propagated plants frequently experience chromosome loss. Although our study does not directly assess the fitness of aneuploids, the frequency of chromosomal instability observed in vegetatively propagated plants compared to second-growth and old-growth trees raises questions about their long-term developmental viability and potential to become established trees. These findings have significant implications for redwood conservation and restoration strategies, especially as methods such as tissue culture propagation becomes the primary mode of producing nursery stock plants used in reforestation.

Telomere-to-telomere gap-free genome assembly of Euchiloglanis kishinouyei

Euchiloglanis kishinouyei is a typical endemic torrent catfish found in the Jinsha River system of the upper Yangtze River in China. It inhabits fast-flowing streams with steep elevation gradients and has evolved unique biological adaptations to thrive in these extreme environments. A high-quality genome provides key insights into the adaptive mechanisms driving its evolution in these harsh conditions. In this study, we successfully assembled the first telomere-to-telomere (T2T) genome of E. kishinouyei, marking the first T2T genome assembly of torrent catfish. The genome spans 886.74 Mb, anchored to 27 chromosomes, with over 99% coverage. The quality value (QV) and Benchmarking Universal Single-Copy Ortholog (BUSCO) scores were 46.96 and 98.50%, respectively, reflecting the high quality of the assembly. We identified repetitive elements accounting for 45.59% (404.23 Mb) of the genome and predicted 24,403 protein-coding genes, 94.37% of which were annotated. This high-fidelity genome assembly provides a valuable resource for future research and lays the foundation for exploring the ecological adaptation mechanisms and evolutionary biology of torrent catfish.

Colora: a Snakemake workflow for complete chromosome-scale de novo genome assembly

MOTIVATION

De novo assembly creates reference genomes that underpin many modern biodiversity and conservation studies. Large numbers of new genomes are being assembled by labs around the world. To avoid duplication of efforts and variable data quality, we desire a best-practice assembly process, implemented as an automated portable workflow.

RESULTS

Here, we present Colora, a Snakemake workflow that produces chromosome-scale de novo primary or phased genome assemblies complete with organelles using Pacific Biosciences HiFi, Hi-C, and optionally Oxford Nanopore Technologies reads as input. Colora is a user-friendly, versatile, and reproducible pipeline that is ready to use by researchers looking for an automated way to obtain high-quality de novo genome assemblies.

AVAILABILITY AND IMPLEMENTATION

The source code of Colora is available on GitHub (https://github.com/LiaOb21/colora) and has been deposited in Zenodo under DOI https://doi.org/10.5281/zenodo.13321576. Colora is also available at the Snakemake Workflow Catalog (https://snakemake.github.io/snakemake-workflow-catalog/? usage=LiaOb21%2Fcolora).

The complete reference genome of Tartary buckwheat and its mutation library provide important resources for genetic studies and breeding

Tartary buckwheat (TB), Fagopyrum tataricum, is an important medicinal and edible crop with a worldwide distribution. However, reference genomes with gaps and mutant population scarcity have hindered functional genomics and genetic improvement of TB. Here, we present a telomere-to-telomere (T2T) gap-free genome assembly of the elite TB inbred line Guiku1 and its ethyl-methyl-sulfonate (EMS)-induced phenotypically rich mutation library. The Guiku1 gap-free genome spans 453.83 Mb, containing 43,441 predicted protein-coding genes. The mutation library includes 751 mutants with stably heritable phenotypes. Whole-genome resequencing of 320 mutants identified 105,682 single-nucleotide polymorphisms (SNPs) and 21,461 insertions/deletions (indels), affecting the protein-coding sequences of 25,986 genes. Genes responsible for the pink stem and petiole mutant trait and flavonoid content variation were identified using forward- and reverse-genetics approaches, respectively. Collectively, the T2T gap-free genome of Guiku1 and its EMS mutation library provide important resources for functional genomics studies and the genetic improvement of TB.

Pathogenomics Insights into Phytophthora capsici and Phytophthora tropicalis -Sibling Species Causing Black Pepper Foot Rot: Genomic Architecture, Metabolic Pathways, and Effector Diversity

Foot rot disease in black pepper, caused by Phytophthora species, is a major threat to cultivation. Along with the well-known Phytophthora capsici, a newly identified species, Phytophthora tropicalis, has also been implicated. Comparative genome analysis of P. capsici 05-06 from Kerala (80.51 Mb, 626 scaffolds) and P. tropicalis 98-93 from Karnataka (73.54 Mb, 302 scaffolds) revealed similar GC content (∼50.5%) and gene counts (19,639 and 17,716, respectively). Genomic ANI analysis clustered them with P. capsici LT1534-B, suggesting a species complex. Both species contain transposable elements (19.35% and 21.31%), indicating adaptive evolution. Pathway mapping highlights roles in carbohydrate metabolism, carbohydrate-active enzymes (CAZymes: 575 and 566), energy production, effector biosynthesis, and molecular signaling. The presence of unique protein families and shared orthologous genes underscores their pathogenic potential. These findings enhance understanding of their evolution and pathogenicity, aiding in the development of targeted management strategies for black pepper foot rot.

Chromosome-level genome assembly of the synanthropic fly Chrysomya megacephala: insights into oviposition location

The oriental latrine fly, Chrysomya megacephala (Diptera: Calliphoridae), is a medically important synanthropic blow fly species characterized by its necrophagy and coprophagy, often observed near carrion and animal feces. Notably, C. megacephala always arrives at carcass earlier than other species. To elucidate the underlying mechanisms behind the host choice in C. megacephala, we present the chromosome-scale genome assembly for this species. The genome size is 816.79 Mb, with a contig N50 of 1.60 Mb. The Hi-C data were anchored to six chromosomes, accounting for 99.93% of the draft assembled genome. Comparative genomic analysis revealed significant expansions in pathways of ligand-gated ion channel activity, passive transmembrane transporter activity, and protein methyltransferase activity, which may be closely associated with host localization and oviposition. After identifying 69 odor-binding proteins (OBPs) in the assembled genome, phylogenetic analysis showed that DmelOBP99b and CmegOBP99b exhibited high homology. Transcriptome analysis demonstrated that the relative expression of CmegOBP99b was consistently the highest during the metamorphosis, and RT-qPCR further confirmed the similar results. Additionally, CmegOBP99b exhibited a strong binding affinity to DMDS (dimethyl disulfide) as determined by molecular docking. To determine the protein expression level of CmegOBP99b in various body parts, we prepared recombinant CmegOBP99b protein and anti-CmegOBP99b polyclonal antibodies. Western blot analysis showed that CmegOBP99b was significantly expressed in the female's head compared to other parts, which is consistent with RT-qPCR results. Therefore, CmegOBP99b may be the primary odor-binding protein responsible for olfactory recognition and the behavioral coordination of C. megacephala. This study not only provides valuable insights into the molecular mechanisms of oviposition localization in C. megacephala but also facilitates further research into the genetic diversity and phylogeny of the Calliphoridae family.

Four near-complete genome assemblies reveal the landscape and evolution of centromeres in Salicaceae

BACKGROUND

Centromeres play a crucial role in maintaining genomic stability during cell division. They are typically composed of large arrays of tandem satellite repeats, which hinder high-quality assembly and complicate our efforts to understand their evolution across species. Here, we use long-read sequencing to generate near-complete genome assemblies for two Populus and two Salix species belonging to the Salicaceae family and characterize the genetic and epigenetic landscapes of their centromeres.

RESULTS

The results show that only limited satellite repeats are present as centromeric components in these species, while most of them are located outside the centromere but exhibit a homogenized structure similar to that of the Arabidopsis centromeres. Instead, the Salicaceae centromeres are mainly composed of abundant transposable elements, including CRM and ATHILA, while LINE elements are exclusively discovered in the poplar centromeres. Comparative analysis reveals that these centromeric repeats are extensively expanded and interspersed with satellite arrays in a species-specific and chromosome-specific manner, driving rapid turnover of centromeres both in sequence compositions and genomic locations in the Salicaceae.

CONCLUSIONS

Our results highlight the dynamic evolution of diverse centromeric landscapes among closely related species mediated by satellite homogenization and widespread invasions of transposable elements and shed further light on the role of centromere in genome evolution and species diversification.

Cythochrome P450-mediated dinotefuran resistance in onion thrips, Thrips tabaci

Onion thrips, Thrips tabaci, have developed resistance to many insecticides, and over the last decade, resistant populations have spread widely across Japan. The cytochrome P450 (CYP) family, a widely conserved detoxification enzyme that metabolizes xenobiotics such as insecticides and phytochemicals, is believed to play important roles in the development of resistance in T. tabaci. However, CYPs involved in insecticide resistance in T. tabaci remain unclear. To comprehensively identify CYPs in T. tabaci, the genome sequences of the thelytokous T. tabaci (ANO strain) were constructed, and 18,965 genes (protein coding) were predicted. We identified 127 CYP genes in the predicted gene set by manual curation, and 38 of these CYP genes belonged to the CYP3 clan, including genes from the CYP6 family, which is one of the most important CYP families involved in resistance to neonicotinoids in many insect pests. To identify the CYPs involved in resistance to dinotefuran, which is one of the neonicotinoids used to control T. tabaci, RNA sequencing of dinotefuran-resistant and dinotefuran-susceptible strains was performed. Results revealed that, TtCYP3652A1, which belongs to the thrips-specific CYP3652A subfamily in the CYP3 clan, was significantly upregulated in the resistant strain. In vitro CYP metabolism assays using insect cells were conducted for TtCYP3652A1 and five highly expressed CYP6 genes. Only TtCYP3652A1 significantly metabolized dinotefuran, which is considered to contribute to detoxification of dinotefuran. As no amino acid mutations were identified in the known target-site genes of neonicotinoids, TtCYP3652A1 was considered to be the main factor involved in the resistance to dinotefuran.

Telomere-to-telomere genome assembly and 3D chromatin architecture of Centella asiatica insight into evolution and genetic basis of triterpenoid saponin biosynthesis

Centella asiatica is renowned for its medicinal properties, particularly due to its triterpenoid saponins, such as asiaticoside and madecassoside, which are in excess demand for the cosmetic industry. However, comprehensive genomic resources for this species are lacking, which impedes the understanding of its biosynthetic pathways. Here, we report a telomere-to-telomere (T2T) C. asiatica genome. The genome size is 438.12 Mb with a contig N50 length of 54.12 Mb. The genome comprises 258.87 Mb of repetitive sequences and 25 200 protein-coding genes. Comparative genomic analyses revealed C. asiatica as an early-diverging genus within the Apiaceae family with a single whole-genome duplication (WGD, Apiaceae-ω) event following the ancient γ-triplication, contrasting with Apiaceae species that exhibit two WGD events (Apiaceae-α and Apiaceae-ω). We further constructed 3D chromatin structures, A/B compartments, and topologically associated domains (TADs) in C. asiatica leaves, elucidating the influence of chromatin organization on expression WGD-derived genes. Additionally, gene family and functional characterization analysis highlight the key role of CasiOSC03 in α-amyrin production while also revealing significant expansion and high expression of CYP716, CYP714, and UGT73 families involved in asiaticoside biosynthesis compared to other Apiaceae species. Notably, a unique and large UGT73 gene cluster, located within the same TAD, is potentially pivotal for enhancing triterpenoid saponin. Weighted gene coexpression network analysis (WGCNA) further highlighted the pathways modulated in response to methyl jasmonate (MeJA), offering insights into the regulatory networks governing saponin biosynthesis. This work not only provides a valuable genomic resource for C. asiatica but also sheds light on the molecular mechanisms driving the biosynthesis of pharmacologically important metabolites.

The genomic insights of intertidal adaptation in Bryopsis corticulans

Many marine green algae thrive in intertidal zones, adapting to complex light environments that fluctuate between low underwater light and intense sunlight. Exploring their genomic bases could help to comprehend the diversity of adaptation strategies in response to environmental pressures. Here, we developed a novel and practical strategy to assemble high-confidence algal genomes and sequenced a high-quality genome of Bryopsis corticulans, an intertidal zone macroalga in the Bryopsidales order of Chlorophyta that originated 678 million years ago. Comparative genomic analyses revealed a previously overlooked whole genome duplication event in a closely related species, Caulerpa lentillifera. A total of 100 genes were acquired through horizontal gene transfer, including a homolog of the cryptochrome photoreceptor CRY gene. We also found that all four species studied in Bryopsidales lack key photoprotective genes (LHCSR, PsbS, CYP97A3, and VDE) involved in the xanthophyll cycle and energy-dependent quenching processes. We elucidated that the expansion of light-harvesting antenna genes and the biosynthesis pathways for siphonein and siphonaxanthin in B. corticulans likely contribute to its adaptation to intertidal light conditions. Our study unraveled the underlying special genetic basis of Bryopsis' adaptation to intertidal environments, advancing our understanding of plant adaptive evolution.

Genomic, transcriptomic and epigenomic signatures of ageing and cold adaptation in the Antarctic clam Laternula elliptica

Genomic data are lacking for most Antarctic marine invertebrates, predicating our ability to understand physiological adaptation and specific life-history traits, such as longevity. The environmental stress response of the Antarctic infaunal clam Laternula elliptica is much diminished in older adult animals compared with younger juvenile individuals. However, the mechanism underlying this reduced capacity is unknown. In this study, we describe and analyse the genome of L. elliptica and use it as a tool to understand transcriptomic responses to shell damage across different age cohorts. Gene expression data were combined with reduced representation enzymic methyl sequencing to identify if methylation was acting as an epigenetic mechanism driving age-dependent transcriptional profiles. Our transcriptomic results demonstrated a clear bipartite molecular response in L. elliptica, associated with a rapid growth phase in juveniles and a stabilization phase in reproductively mature adults. Genes active in the response to damage repair in juvenile animals are silent in adults but can be reactivated after several months following damage stimulus; however, these genes were not methylated. Hence, the trigger for this critical and imprinted change in physiological state is, as yet, unknown. While epigenetics is likely involved in this process, the mechanism is unlikely to be methylation.

The First De Novo HiFi Genome Assemblies for Three Clownfish-hosting Sea Anemone Species (Anthozoa: Actiniaria)

The symbiosis between clownfish and giant tropical sea anemones (Order Actiniaria) is one of the most iconic on the planet. Distributed on tropical reefs, 28 species of clownfishes form obligate mutualistic relationships with 10 nominal species of venomous sea anemones. Our understanding of the symbiosis is limited by the fact that most research has been focused on the clownfishes. Chromosome-scale reference genomes are available for all clownfish species, yet only short reads-based reference genomes are available for five species of host sea anemones. Recent studies have shown that the clownfish-hosting sea anemones belong to three distinct clades of sea anemones that have evolved symbiosis with clownfishes independently. Here we present the first high-quality long-read assemblies for three species of clownfish-hosting sea anemones belonging to each of these clades: Entacmaea quadricolor, Stichodactyla haddoni, and Radianthus doreensis. PacBio HiFi sequencing yielded 1,597,562, 3,101,773, and 1,918,148 million reads for E. quadricolor, S. haddoni, and R. doreensis, respectively. All three assemblies were highly contiguous and complete with N50 values above 4 Mb and BUSCO completeness above 95% on the Metazoa dataset. Genome structural annotation with BRAKER3 predicted 20,454, 18,948, and 17,056 protein-coding genes in E. quadricolor, S. haddoni, and R. doreensis genome, respectively. These new resources will form the basis of comparative genomic analyses that will allow us to deepen our understanding of this mutualism from the host perspective.

Chromosomal level genome assembly of medicinal plant Rosa laevigata

Rosa laevigata Michx., an endemic perennial herbaceous plant in China, possesses significant medicinal value in traditional herbal practices. However, the absence of a reference genome has hindered its development and utilization. In this study, we present a chromosome-level de novo genome assembly of two haplotypes (Hap1 and Hap2) of R. laevigata by integration of Hifi long reads, BGI short reads, and Hi-C reads. The assembled Hap1 genome spans 493 Mb, Hap2 genome spans 479 Mb, and both of them were assigned to 7 chromosomes each. The mapping rate of BGI short reads to the two haplotypes genome is approximately 99.26% and 99.23%, and BUSCO assessment reveals that 98.6% and 98.7% of the genes are complete. Furthermore, we predicted 43,480 and 41,251 protein-coding genes in two haplotype genomes, respectively. The chromosome-level genome of R. laevigata enhances the genetic resources available for Rosa species and lays the groundwork for subsequent medicinal development.

Chromosome-Level Genome Assembly of the Asian Tramp Snail Bradybaena similaris (Stylommatophora: Camaenidae)

While terrestrial land snails have long been used for evolutionary research, a lack of high-quality genomic resources has impeded recent progress. Bradybaena snails in particular have numerous intriguing traits that make them a good model for studying evolution, including shell pattern polymorphism and convergent evolution. They are also introduced and invasive across the world. In this study, we present a chromosome-level genome assembly of the Asian tramp snail Bradybaena similaris, utilizing 88-fold Illumina short-read sequences, 125-fold Nanopore long-read sequences, 63-fold PacBio HiFi sequences, and 47-fold Hi-C sequences. The assembled genome of 2.18 Gb is anchored to 28 chromosomes and exhibits high completeness (single copy, 91.7%; duplicates, 7.1%) and contiguity (N50 of 75.6 Mb). Additionally, we also obtained a high-quality transcriptome for annotation. This resource represents the first chromosome-level assembly for snails in the superfamily Helicoidea, which includes more than 5,000 species of terrestrial snails, and will facilitate genomic study in Bradybaena and, more broadly, in the superfamily Helicoidea.

Genome Evolution of Two Intertidal Sargassum Species (S. fusiforme and S. thunbergii) and Their Response to Abiotic Stressors

Sargassum fusiforme and Sargassum thunbergii are ecologically and commercially important seaweeds that thrive in intertidal zones and are frequently exposed to extreme variation in environmental stress. Despite their importance, limited genomic information exists for these species, which hinders a comprehensive understanding of the evolution and adaptation of the genus Sargassum to marine coastal habitats. Two Sargassum genomes were generated in this study. The genome sizes of S. fusiforme and S. thunbergii were 438 and 376 Mbp, respectively, which are larger than the published genomes of the brown seaweed group, Ectocarpales. Expansion of the Sargassum genomes was significantly explained by the spread of transposable elements (TEs). Additionally, extensive gene duplications and their diversification occurred particularly through tandem, proximal, and dispersed duplications, which likely played an important role in response to environmental stress. Differentially expressed gene analysis under ambient and desiccation stress conditions confirmed that some duplicated genes respond to stress. We identified enhanced disease susceptibility 1 (EDS1) genes that promote salicylic acid (SA) biosynthesis, and their expansion is likely linked to TEs. We also confirmed the potential role of EDS1 by analyzing its subcellular localization (in Arabidopsis thaliana) and quantified the increased SA levels under desiccation conditions. This study demonstrates that the genomic evolution has played a critical role in allowing S. fusiforme and S. thunbergii to adapt to harsh intertidal conditions. The genomic resources of Sargassum species provided here will be instrumental in advancing future research, aiding in the understanding of adaptive evolution in brown algae.

Evolutionary history of magnoliid genomes and benzylisoquinoline alkaloid biosynthesis

Benzylisoquinoline alkaloids (BIAs) are important metabolites synthesized in early-diverging eudicots and magnoliids, yet the genetic basis of BIA biosynthesis in magnoliids remains unclear. Here, we decode the genomes of two magnoliid species, Saruma henryi and Aristolochia manshuriensis, and reconstruct the ancestral magnoliid karyotype and infer the chromosomal rearrangement history following magnoliid diversification. Metabolomic, transcriptomic, and phylogenetic analyses reveal the intermediate chemical components and genetic basis of BIA biosynthesis in A. manshuriensis. Although the core enzymes involved in BIA synthesis appear to be largely conserved between early-diverging eudicots and magnoliids, the biosynthetic pathways in magnoliids seem to exhibit greater flexibility. Significantly, our investigation of the evolutionary history of BIA biosynthetic genes revealed that almost all were duplicated before the emergence of extant angiosperms, with only early-diverging eudicots and magnoliids preferentially retaining these duplicated genes, thereby enabling the biosynthesis of BIAs in these groups.

Chromosome-level genomes of Arctic and Antarctic mosses: Aulacomnium turgidum and Polytrichastrum alpinum

Bryophytes play a crucial role in the ecosystems of polar regions. These simple plants are among the predominant vegetation types in both Arctic and Antarctic landscapes, where they contribute significantly to biodiversity and ecological stability. Here, we report the chromosome-level genomes of two polar moss species, the Arctic Aulacomnium turgidum and Antarctic Polytrichastrum alpinum. Utilizing a combination of Illumina short reads, Nanopore long reads, and Hi-C data, we assembled genomes of 277.84 Mb for A. turgidum and 498.33 Mb for P. alpinum, respectively. These assemblies were anchored to 11 chromosomes for A. turgidum and 8 chromosomes for P. alpinum. Both species exhibited a sex chromosome with distinct genomic characteristics. Gene annotations revealed 25,999 protein-coding genes in A. turgidum and 28,070 in P. alpinum. The high completeness of the gene space was validated via BUSCO, achieving impressive scores of 98.2% and 98.0%. These high-quality genomes provide critical resources for studying the adaptive evolution and stress tolerance mechanisms of mosses in extreme polar environments.

De novo, high-quality assembly and annotation of the halophyte grass Aeluropus littoralis draft genome and identification of A20/AN1 zinc finger protein family

BACKGROUND

Aeluropus littoralis is considered a valuable natural forage plant for ruminant livestock and is highly tolerant to extreme abiotic stresses, especially salinity, drought, and heat. It is a monocotyledonous halophyte, has salt glands, performs C4-type photosynthesis and has a close genetic relationship with cereal crops. Moreover, previous studies have shown its huge potential as a reservoir of genes and promoters to understand and improve abiotic stress tolerance in crops.

RESULTS

The sequencing and hybrid assembly of the A. littoralis genome (2n = 2X = 20) using short and long reads from the BGISeq-500 and PacBio high-fidelity (HiFi) sequencing platforms, respectively. Using the k-mer analysis method, the haploid genome size of A. littoralis was estimated to be 360 Mb (with a heterozygosity rate of 1.88%). The hybrid assembled genome included 4,078 contigs with a GC content of 44% and covered 348 Mb. The longest contig and the N50 values were 5.1 Mb and 133.77 kb, respectively. The Benchmarking Universal Single Copy Ortholog (BUSCO) value was 91.1%, indicating good integrity of the assembled genome. The discovered repetitive elements accounted for 90.6 Mb, representing 26.03% of the total genome, and included a significant component of transposable elements (11.48%, ~40 Mb). Using a homology-based approach, 35,147 genes were predicted from the genome assembly. We next focused our analysis on the zinc-finger A20/AN1 gene family, a member of which (AlSAP) was previously shown to confer increased tolerance to osmotic and salt stresses when it was over-expressed in tobacco, wheat, and rice. Here, we identified the complete set of members of this family in the Aeluropus littoralis genome, thereby laying the foundation for their future functional analysis in cereal crops. In addition, the expression patterns of four novel genes from this family were analyzed by qPCR.

CONCLUSION

This resource and our findings will contribute to improve the current understanding of salinity tolerance in halophytes while providing useful genes and allelic variation to improve salinity and drought tolerance in cereals through genetic engineering and gene editing, respectively.

The First Genome Assembly Of The Dogwhelk Nucella lapillus, a Bioindicator Species For The Marine Environment

The dogwhelk (Nucella lapillus) is a predatory marine gastropod widely distributed across temperate intertidal zones. Renowned for its ecological role in controlling prey populations, N. lapillus is also an important bioindicator species for marine pollution through imposex. The molecular genetic basis of imposex, characterised by the abnormal development of male sex organs in females and reductions in fertility and lifespan, however remains poorly understood due to the absence of a reference genome sequence. Here we provide the first genome assembly comprising 2.41 Gb of sequence, predicted to encode 47,238 proteins. This inaugural assembly lays the foundations for implementing genomic approaches to better quantify and characterise imposex, in addition to elucidating adaptations to life within changeable intertidal ecosystems. To counter challenges of DNA fragmentation and contamination often associated with the sequencing of marine organisms, we found that a hybrid approach that integrates complementary long-read data from PacBio HiFi and Oxford Nanopore Technology (ONT) platforms helped maximise the final assembly. This innovative combination may be a useful approach for similar marine species.

Integrative Taxonomy for Species Delimitation: A Case Study in Two Widely Accepted Yet Morphologically Confounding Rosa Species Within Sect. Pimpinellifoliae (Rosaceae)

The use of morphological traits as a practical approach for delimiting taxa at various ranks has long been regarded as a reliable basis for taxonomy. However, its efficacy has been increasingly called into question in many taxonomic groups due to its inherent limitations, such as failing to account for phenotypic plasticity, ecologically driven variation (e.g., ecotypes), and parallel evolution. These factors often introduce ambiguity or misleading similarities, thereby obscuring the true evolutionary relationships among taxa, particularly in the context of species delimitation. In the present study, we employ an integrated methodology that combines quantitative morphological analyses, whole-genome data, and ecological measurements to resolve the species boundaries of two morphologically similar roses, Rosa sericea and Rosa hugonis, which have long been considered as two distinct species but lack clear morphological boundaries. Our findings reveal that the unbiased analysis of morphological data based on a large and representative sample size was insufficient to identify effective diagnostic traits. However, when complemented with genome-wide population-level sequencing data or integrated with geographic and ecological niche assessments, the delineation of species boundaries was significantly improved. Furthermore, ecological data provide additional insight into the abiotic factors driving interspecific and intraspecific divergence. By integrating multiple lines of evidence-spanning genomic (intrinsic) and phenotypic (extrinsic) traits-and incorporating the interaction between species and their environments, species boundaries can be delineated with greater confidence. A well-defined species can thus be established through the mutual corroboration of diverse datasets, thereby ensuring a more rigorous and comprehensive taxonomic framework.

Salty secrets of Halobacterium salinarum AD88: a new archaeal ecotype isolated from Cuatro Cienegas Basin

The Cuatro Cienegas Basin (CCB) in Mexico, represents a unique ecological habitat, characterized by extreme and fluctuating conditions, providing a window into ancient evolutionary processes. This basin, characterized by hypersalinity and phosphorus scarcity, harbors diverse microbial communities that exhibit remarkable adaptations to oligotrophic conditions. Among these, Halobacterium salinarum, a halophilic archaeon known for its polyploid genome and metabolic versatility, has been extensively studied as a model for extremophile survival. However, only a limited number of H. salinarum strains have been successfully cultured and characterized to date. Here, we report the isolation and genomic analysis of a novel Halobacterium salinarum strain, AD88, from microbial mats at the Archaean Domes site in the CCB. This strain displays unique genomic features, including smaller plasmid sizes and distinctive metabolic pathways for phosphorus and sulfur utilization. Comparative analyses with other Halobacterium strains revealed genetic innovations, such as genes involved in sulfolipid biosynthesis, enabling membrane stability in phosphorus-depleted environments, and adaptations for horizontal gene transfer, which facilitate genomic flexibility in response to environmental pressures. This study reveals that H. salinarum AD88 is the first recorded diploid strain of Halobacterium, a feature previously undocumented in this genus. Phylogenomic reconstruction positioned AD88 tightly within the Halobacterium clade, reflecting its evolutionary history within the genus. Pangenome analysis further highlighted the open nature of the Halobacterium genus, with AD88 contributing novel accessory genes linked to ecological specialization. These findings emphasize the evolutionary significance of the CCB as a natural laboratory for studying microbial adaptation and expand our understanding of archaeal genomic diversity and functional innovation under extreme conditions.

Spiral phyllotaxis predicts left-right asymmetric growth and style deflection in mirror-image flowers of Cyanella alba

Many animals and plants show left-right (LR) asymmetry. The LR asymmetry of mirror-image flowers has clear functional significance, with the reciprocal placement of male and female organs in left- versus right-handed flowers promoting cross-pollination. Here, we study how handedness of mirror-image flowers is determined and elaborated during development in the South African geophyte Cyanella alba. Inflorescences of C. alba produce flowers with a largely consistent handedness. However, this handedness has no simple genetic basis and individual plants can switch their predominant handedness between years. Rather, it is the direction of the phyllotactic spiral that predicts floral handedness. Style deflection is driven by increased cell expansion in the adaxial carpel facing the next oldest flower compared to the other adaxial carpel. The more expanding carpel shows transcriptional signatures of increased auxin signaling and auxin application can reverse the orientation of style deflection. We propose that a recently described inherent LR auxin asymmetry in the initiating organs of spiral phyllotaxis determines handedness in C. alba, creating a stable yet non-genetic floral polymorphism. This mechanism links chirality across different levels of plant development and exploits a developmental constraint in a core patterning process to produce morphological variation of ecological relevance.

Chromosome-level genome assembly of an important ethnic medicinal plant Callicarpa nudiflora

Callicarpa nudiflora is one of high medicinal and economic value plants in China, which was recorded in Chinese pharmacopoeia (2020 edition) and widely used to treat tropical bacterial infections, acute infectious hepatitis, and internal and external bleeding. In this study, we assembled the C. nudiflora genome with a size of approximately 597.82 Mb and a contig N50 length of 34.14 Mb. A total of 98.61% of the assembled sequences were anchored to 17 pseudo-chromosomes by using PacBio long reads and Hi-C sequencing data. We totally predicted 31,266 protein-coding genes, of which 92.45% could be annotated in databases such as NR, GO, KOG, and KEGG. In addition, we identified 2,303 rRNAs, 884 MicroRNAs and 531 tRNAs from the genome. The chromosome-scale genome represents a crucial resource for investigating the molecular mechanisms underlying the biosynthesis of medicinal components and facilitates the exploration and conservation of C. nudiflora.

Still waters run deep in large-scale genome rearrangements of morphologically conservative Polyplacophora

A major question in animal evolution is how genotypic and phenotypic changes are related, and another is when and whether ancient gene order is conserved in living clades. Chitons, the molluscan class Polyplacophora, retain a body plan and general morphology apparently little changed since the Palaeozoic. We present a comparative analysis of five reference quality genomes, including four de novo assemblies, covering all major chiton clades, and an updated phylogeny for the phylum. We constructed 20 ancient molluscan linkage groups (MLGs) and show that these are relatively conserved in bivalve karyotypes, but in chitons they are subject to re-ordering, rearrangement, fusion, or partial duplication and vary even between congeneric species. The largest number of novel fusions is in the most plesiomorphic clade Lepidopleurida, and the chitonid Liolophura japonica has a partial genome duplication, extending the occurrence of large-scale gene duplication within Mollusca. The extreme and dynamic genome rearrangements in this class stands in contrast to most other animals, demonstrating that chitons have overcome evolutionary constraints acting on other animal groups. The apparently conservative phenome of chitons belies rapid and extensive changes in genome.

Genomes of the Caribbean reef-building corals Colpophyllia natans, Dendrogyra cylindrus, and Siderastrea siderea

Coral populations worldwide are declining rapidly due to elevated ocean temperatures and other human impacts. The Caribbean harbors a high number of threatened, endangered, and critically endangered coral species compared with reefs of the larger Indo-Pacific. The reef corals of the Caribbean are also long diverged from their Pacific counterparts and may have evolved different survival strategies. Most genomic resources have been developed for Pacific coral species which may impede our ability to study the changes in genetic composition of Caribbean reef communities in response to global change. To help fill the gap in genomic resources, we used PacBio HiFi sequencing to generate the first genome assemblies for 3 Caribbean reef-building corals, Colpophyllia natans, Dendrogyra cylindrus, and Siderastrea siderea. We also explore the genomic novelties that shape scleractinian genomes. Notably, we find abundant gene duplications of all classes (e.g. tandem and segmental), especially in S. siderea. This species has one of the largest genomes of any scleractinian coral (822 Mb) which seems to be driven by repetitive content and gene family expansion and diversification. As the genome size of S. siderea was double the size expected of stony corals, we also evaluated the possibility of an ancient whole-genome duplication using Ks tests and found no evidence of such an event in the species. By presenting these genome assemblies, we hope to develop a better understanding of coral evolution as a whole and to enable researchers to further investigate the population genetics and diversity of these 3 species.

High-quality chromosome-level genome assembly of the whitespotted conger (Conger myriaster)

The whitespotted conger (Conger myriaster) is an ecologically and economically significant benthic marine species widely distributed across East Asia's coastal waters. Despite this importance, the genomic resources for this species remain limited, hindering evolutionary and aquaculture research. Here, we present the first high-quality chromosome-level genome assembly of C. myriaster using PacBio CLR, WGS, 10X Genomics and Hi-C data. The resulting 1.09 Gb genome assembly exhibits excellent contiguity, with 97.49% of sequences anchored onto 19 chromosomes. The assembled genome achieved a BUSCO completeness stands at 98.00%, containing 34.80% repetitive sequences and 24,063 predicted protein-coding genes. This foundational genomic resource overcomes a major limitation, providing the essential framework for future investigations into the evolutionary adaptations and for the genetic improvement of C. myriaster in aquaculture.

A conserved terpene cyclase gene in Sanghuangporus for abscisic acid-related sesquiterpenoid biosynthesis

BACKGROUND

The medicinal mushroom Sanghuangporus is renowned in East Asia for its potent therapeutic properties, attributed in part to its bioactive sesquiterpenoids. However, despite their recognized medicinal potential, the biosynthetic pathways and specific enzymes responsible for sesquiterpenoid production in Sanghuangporus remain unexplored, limiting opportunities to optimize their medicinal applications.

RESULTS

Sesquiterpenoids from four Sanghuangporus species were extracted through targeted isolation using mass spectrometry (MS)-based metabolomics, resulting in the discovery of six known abscisic acid-related compounds and one new compound, whose structure was determined through spectroscopic and computational analysis. We employed a natural product genome mining approach to identify a putative biosynthetic gene cluster (BGC) containing a sesquiterpene synthase gene, ancA, associated with the detected compounds. Biosynthetic pathways for these compounds were proposed based on an integrative approach combining BGC analysis and MS2 fragment-based dereplication. Further analyses revealed that the gene content and synteny of the ancA BGC are relatively well-conserved across Sanghuangporus species but less so outside the genus.

CONCLUSIONS

A sesquiterpene synthase gene, its associated BGC, and the biosynthetic pathway for a group of detected abscisic acid-related sesquiterpenoids in Sanghuangporus were predicted through genomic and metabolic data analyses. This study addresses a critical gap in understanding the genetic basis of sesquiterpenoid production in Sanghuangporus and offers insights for future research on engineering metabolic pathways to enhance sesquiterpenoid production for medicinal use.

High-quality genome of allotetraploid Avena barbata provides insights into the origin and evolution of B subgenome in Avena

Avena barbata, a wild oat species within the genus Avena, is a widely used model for studying plant ecological adaptation due to its strong environmental adaptability and disease resistance, serving as a valuable genetic resource for oat improvement. Here, we phased the high-quality chromosome-level genome assembly of A. barbata (6.88 Gb, contig N50 = 53.74 Mb) into A (3.57 Gb with 47,687 genes) and B (3.31 Gb with 46,029 genes) subgenomes. Comparative genomics and phylogenomic analyses clarified the evolutionary relationships and trajectories of A, B, C and D subgenomes in Avena. We inferred that the A subgenome donor of A. barbata was Avena hirtula, while the B subgenome donor was probably an extinct diploid species closely related to Avena wiestii. Genome evolution analysis revealed the dynamic transposable element (TE) content and subgenome divergence, as well as extensive structure variations across A, B, C, and D subgenomes in Avena. Population genetic analysis of 211 A. barbata accessions from distinct ecotypes identified several candidate genes related to environmental adaptability and drought resistance. Our study provides a comprehensive genetic resource for exploring the genetic basis underlying the strong environmental adaptability of A. barbata and the molecular identification of important agronomic traits for oat breeding.

RAmbler resolves complex repeats in human Chromosomes 8, 19, and X

Repetitive regions in eukaryotic genomes often contain important functional or regulatory elements. Despite significant algorithmic and technological advancements in genome sequencing and assembly over the past three decades, modern de novo assemblers still struggle to accurately reconstruct highly repetitive regions. In this work, we introduce RAmbler (Repeat Assembler), a reference-guided assembler specialized for the assembly of complex repetitive regions exclusively from Pacific Biosciences (PacBio) HiFi reads. RAmbler (1) identifies repetitive regions by detecting unusually high coverage regions after mapping HiFi reads to the draft genome assembly, (2) finds single-copy k-mers from the HiFi reads, (i.e., k-mers that are expected to occur only once in the genome), (3) uses the relative location of single-copy k-mers to barcode each HiFi read, (4) clusters HiFi reads based on their shared barcodes, (5) generates contigs by assembling the reads in each cluster, and (6) generates a consensus assembly from the overlap graph of the assembled contigs. Here, we show that RAmbler can reconstruct human centromeres and other complex repeats to a quality comparable to the manually curated Telomere-to-Telomere human genome assembly. Across more than 250 synthetic data sets, RAmbler outperforms hifiasm, LJA, HiCANU, and Verkko across various parameters such as repeat lengths, number of repeats, heterozygosity rates, and depth of sequencing.

Integrated genomic and transcriptomic analyses reveal the genetic and molecular mechanisms underlying hawthorn peel color and seed hardness diversity

Hawthorn (Crataegus pinnatifida) fruit peel color and seed hardness are key traits that significantly impact economic value. We present here the high-quality chromosome-scale genomes of two cultivars, including the hard-seed, yellow-peel C. pinnatifida "Jinruyi" (JRY) and the soft-seed, red-peel C. pinnatifida "Ruanzi" (RZ). The assembled genomes comprising 17 chromosomes are 809.1 Mb and 760.5 Mb in size, achieving scaffold N50 values of 48.5 Mb and 46.8 Mb for JRY and RZ, respectively. Comparative genomic analysis identifies 3.6-3.8 million single nucleotide polymorphisms, 8.5-9.3 million insertions/deletions, and approximately 30 Mb of presence/absence variations across different hawthorn genomes. Through integrating differentially expressed genes and accumulated metabolites, we filter candidate genes CpMYB114 and CpMYB44 associated with differences in hawthorn fruit peel color and seed hardness, respectively. Functional validation confirms that the CpMYB114-CpANS regulates anthocyanin biosynthesis in hawthorn peels, contributing to the observed variation in peel color. CpMYB44-CpCOMT is significantly upregulated in JRY and is verified to promote lignin biosynthesis, resulting in the distinction in seed hardness. Overall, this study reveals the new insights into understanding of distinct peel pigmentation and seed hardness in hawthorn and provides an abundant resource for molecular breeding.

Chromosome-level genome assembly and annotation of Anthurium amnicola

Anthurium amnicola is in the monocot family Araceae, subfamily Pothoideae and is a contributing species in Hawaii floriculture industry hybrids. To support future genetic improvements to this commodity, we sequenced and assembled the A. amnicola genome to chromosome-scale using PacBio HiFi and short-read Hi-C sequencing. A total of 98.51% of the 4.79 Gb genome is anchored into 15 chromosomes, with 99.2% gene completeness and a high LTR assembly index (LAI) score of 21.73, indicative of a complete, high-quality assembly. Annotation reveals the presence of 20,380 protein-coding genes, with 78.52% of the genome composed of repetitive sequences, predominantly long terminal repeat retrotransposons (LTR-RT). Phylogenetic analysis identified evolutionary relationships between A. amnicola and representative species in the Araceae and other plant families. This study provides the first reference genome sequence for the neotropical genus Anthurium and insights into Araceae evolution, benefiting the floriculture industry and evolutionary studies.

Haplotyped genome mapping and functional characterization of a blueberry anthocyanin acetyltransferase (AAT) controlling the accumulation of acylated anthocyanins

Blueberry has a diversity of anthocyanins that confer its characteristic blue-coloured skin. Whilst most cultivars produce only anthocyanin glycosides, some can add aliphatic or aromatic groups to the sugar moiety to create acylated anthocyanins. Due to their enhanced stability, acylated anthocyanins represent an attractive breeding target in blueberry. In this study, a haplotype-resolved assembly of a previously identified quantitative trait locus on chromosome 2 of 'Hortblue Petite' (Vaccinium corymbosum) was created to identify candidate anthocyanin acyltransferase genes. One full-length gene (VcAAT1a) was selected based on quantitative PCR expression profiling and transient expression in tobacco leaves and in strawberry and blueberry fruit flesh. In all three systems, VcAAT1a was able to produce a range of acylated anthocyanins in planta. Recombinant VcAAT1a protein demonstrated that, while VcAAT1a was able to act on both anthocyanin 3-O-glucosides and 3-O-galactosides, it could only utilize acetyl-CoA as an acyl donor. Protein modelling using AlphaFold suggested that this restricted range in acyl donors may be due to a spatially restricted sub-pocket in the acyl-binding site of VvAAT1. Finally, LUC/REN promoter activation assays revealed that the VcAAT1a promoter was transactivated by the VcMYBPA1 and VcMYBPA2 transcription factors, further expanding our knowledge of anthocyanin regulation in blueberry.

The genome sequence of the harbour porpoise, Phocoena phocoena (Linnaeus, 1758)

We present a genome assembly from a female specimen of Phocoena phocoena (harbour porpoise; Chordata; Mammalia; Artiodactyla; Phocoenidae). The genome sequence has a total length of 2,512.71 megabases. Most of the assembly (94.41%) is scaffolded into 22 chromosomal pseudomolecules, including the X sex chromosome. The mitochondrial genome has also been assembled, with a length of 16.38 kilobases.

The genome sequence of long-finned pilot whale, Globicephala melas (Traill, 1809)

We present a genome assembly from a male specimen of Globicephala melas (long-finned pilot whale; Chordata; Mammalia; Artiodactyla; Delphinidae). The genome sequence has a total length of 2,651.28 megabases. Most of the assembly (89.15%) is scaffolded into 23 chromosomal pseudomolecules, including the X and Y sex chromosomes. The mitochondrial genome has also been assembled, with a length of 16.39 kilobases. Gene annotation of this assembly on Ensembl identified 17,911 protein-coding genes.

Whole Genome Sequence of the gut commensal protist Tritrichomonas musculus isolated from laboratory mice

Tritrichomonas musculus is a commensal protist colonizing the large intestine of laboratory mice. Parasite colonization reshapes the gut microbiome and modulates mucosal immunity. This parasite is refractory to axenic culture. In order to facilitate functional genomic investigations we assembled a 193.49 Mbp high quality reference genome from FACS-purified parasites recovered from monocolonized mice using an integrated approach that combined long-read (PacBio and Oxford Nanopore) sequencing technologies for the draft genome assembly. The genome assembled into 756 contigs and RNA-Seq data was used to support the gene models for 46,131 annotated genes. Of these, 24,215 genes had an InterPro, Enzyme Commission and/or a Gene Ontology annotation. BUSCO analyses established that 53% of the genome annotations matched with available BUSCO genes in the eukaryote_odb10 database. This high quality reference genome will serve as a valuable resource to develop a metabolic and genetic model to grow T. musculus axenically and study genes relevant to its biology, life cycle transmission, and pathogenesis.

The genome sequence of the short-beaked common dolphin, Delphinus delphis Linnaeus, 1758

We present a genome assembly from a male specimen of Delphinus delphis (short-beaked common dolphin; Chordata; Mammalia; Artiodactyla; Delphinidae). The genome sequence has a total length of 2,663.52 megabases. Most of the assembly (88.76%) is scaffolded into 23 chromosomal pseudomolecules, including the X and Y sex chromosomes. The mitochondrial genome has also been assembled, with a length of 16.39 kilobases. Gene annotation of this assembly at Ensembl identified 17,797 protein-coding genes.

Chromosome-scale genome assembly and annotation of Xenocypris argentea

Xenocypris argentea is a small to medium-sized freshwater cyprinid fish. It distributes widely in the rivers and lakes of China, and is often used as a tool fish for water quality improvement and optimizing aquaculture structures. In recent years, natural populations of X. argentea have decreased rapidly due to human activities, yet little is known about the genetics and genomics of this fish. In the present work, we reported a chromosome-level reference genome of X. argentea based on PacBio HiFi, Hi-C and Illumina paired-end sequencing technologies. The assembled genome was 984.96 Mb in length, with a contig N50 of 36.02 Mb. Using Hi-C interaction information, 99.47% of the contigs were anchored onto 24 chromosomes, and 18 of the chromosomes were gap-free. Further analysis identified 560.27 Mb of repeat sequences and 28,533 protein-coding genes in the genome, of which, 95.62% (27,284) genes were functionally annotated. This high-quality genome offers an invaluable resource for population genetics and phylogeny, comparative genomics, adaptive evolution and functional exploration of X. argentea.

Chromosome-level genome assembly and annotation of the sharpsnout seabream (Diplodus puntazzo)

Diplodus puntazzo is a demersal fish inhabiting the Mediterranean Sea and the eastern Atlantic and plays an important ecological role in coastal areas. Here, we present the first nuclear genome assembly and annotation of this species and genus. We used a combination of PacBio CLR long reads, Illumina short reads and chromatin capture reads (Omni-C) to generate a chromosome-level assembly. The nuclear genome assembly has a total span of 788 Mb, containing 24 chromosome-scale scaffolds (98.76% of the total length), coinciding with its known karyotype. By using RNA-Seq data from D. puntazzo and gene models from closely related species, we also generated a high-quality nuclear annotation. We predicted a total of 87,572 transcripts from the nuclear genome, 26,838 coding, and 60,734 non-coding that included lncRNA, snoRNA, and tRNAs. We also assembled and annotated the mitochondrial genome, circularized in 16,642 bp comprising 13 protein-coding genes, 2 rRNA, and 22 tRNA. This high-quality reference genome will enrich the current genomic resources available to the large fish scientific community.

Chromosome-level genome assembly of the traditional medicinal plant Lindera aggregata

Lindera aggregata is a renowned medicinal plant in China, particularly the variety from Tiantai, Zhejiang Province, which is esteemed for its superior medicinal properties. Beyond its medicinal value, it holds significant economic potential and phylogenetic significance. Utilizing a range of sequencing techniques, we have successfully assembled and annotated a high-quality chromosome-level genome of L. aggregata. The assembled genome spans approximately 1.59 Gb, with a scaffold N50 length of 132.62 Mb. Approximately 93.07% of the assembled sequences have been anchored to 12 pseudo-chromosomes, and 70.02% of the genome consists of repetitive sequences. According to the annotations, a total of 33,283 genes are identified, of which 96.95% can predict function. This high-quality chromosome-level assembly and annotation will greatly assist in the development and utilization of L. aggregata's valuable resources, and also provide a crucial molecular foundation for investigating the evolutionary relationships within the Lauraceae family and the mechanisms behind the synthesis of active ingredients in L. aggregata.

Chromosome-level genome assembly of the crofton weed (Ageratina adenophora)

Crofton weed (Ageratina adenophora), a significant invasive species, extensively disrupts ecosystem stability, leading to considerable economic losses. However, genetic insights into its invasive mechanisms have been limited by a lack of genomic data. In this study, we present the successful de novo assembly of the triploid genome of A. adenophora, leveraging long-read PacBio Sequel, optical mapping, and Hi-C sequencing. Our assembly resolved into a haplotype-resolved genome comprising 51 chromosomes, with a total size of ~3.82 Gb and a scaffold N50 of 70.8 Mb. BUSCO analysis confirmed the completeness of 97.71% of genes. Genome annotation revealed 3.16 Gb (76.44%) of repetitive sequences and predicted 123,134 protein-coding genes, with 99.03% functionally annotated. The high-quality reference genome will provide valuable genomic resources for future studies on the evolutionary dynamics and invasive adaptations of A. adenophora.