Biology subjects

Shimizu, M.

Publications and source records attributed to Shimizu, M..

At least 19 recordsLinked to original sources

bioRxiv2026

Secretory ferritins mediate iron delivery during magnetite tooth formation in chitons

Iron is essential to most organisms, yet unbound iron is toxic, necessitating tight regulation of its storage and transport. Chitons concentrate extraordinary amounts of iron in radular tissue to form magnetite-mineralized teeth, but how iron is supplied to developing teeth remains unclear. Here, synchrotron radiation X-ray fluorescence mapping resolved the spatiotemporal redistribution of iron from the radular epithelium toward developing teeth. Integrated transcriptomic and proteomic analyses identified secretory ferritin subunits in radular tissue whose genes were highly expressed in the midgut gland and whose proteins were also present in the hemolymph. In vivo fluorescence tracking showed that circulating ferritin was selectively taken up by the radular epithelium, and following injection of Ag-loaded hemolymph ferritin, Ag was detected in developing teeth. Together, these findings support a model in which secretory ferritins produced in the midgut gland transport iron through the hemolymph to the radula, enabling the pronounced iron accumulation required for tooth mineralization.

molecular biology↗

bioRxiv2026

Rice blast fungus hijacks a rice RALF peptide to initiate infection

Plant-derived peptides regulate immunity and host-microbe interactions, but whether fungal pathogens exploit endogenous plant peptides for infection-site selection remains largely unknown. Rapid alkalinization factors (RALFs) are a family of plant peptide hormones that contribute to plant development, reproduction, stress responses, and cell-wall organization. Here, we show that OsRALF7, which is an immune-activating peptide in rice (Oryza sativa), is co-opted by the rice blast fungus Magnaporthe oryzae as a host-derived cue for appressorium formation, specialized infection structures required for host penetration. While synthetic OsRALF7 peptide induced defense responses in rice suspension cells, the same peptide induced appressorium formation in M. oryzae. OsRALF7-induced appressorium formation was associated with activation of the cAMP/PKA and Pmk1 MAPK pathways and required a hydrophobic surface. M. oryzae inoculated onto Osralf7 knockout plants formed fewer appressoria, and the positioning of these appressoria relative to the boundaries between two adjacent plant epidermal cells was altered. These findings suggest that OsRALF7 provides positional information for infection initiation for M. oryzae. OsRALF7 localized to the plasma membrane and cell wall in rice, and its appressorium-inducing activity required a conserved YISY motif and cysteine residues. This activity was not conserved in Colletotrichum higginsianum, as RALF23 from Arabidopsis thaliana did not induce appressorium formation but instead showed antifungal activity. Together, these findings uncover a dual function of endogenous plant immune-modulating RALF peptides at the plant-pathogen interface, where they can be exploited by M. oryzae as a host-derived cue for infection initiation while also retaining antifungal activity against other fungal species.

plant biology↗

bioRxiv2026

Evolution of an unstable sex determination system in white Guinea yam (Dioscorea rotundata)

Plants often produce unstable sex phenotypes; however, the underlying evolutionary and molecular mechanisms are unclear. In white Guinea yam (Dioscorea rotundata), the most economically important tuber crop, genetic improvement is critical for food security but remains constrained by dioecy and complex sex phenotypes. White Guinea yam has a ZZ/ZW sex determination system in which ZZ individuals are consistently male, whereas ZW individuals can be female, male, or monoecious. Here we show that chromosome 11 is the sex chromosome, featuring a 1.2-Mb inversion between the Z and W chromosomes. A 170-kb W-specific region carries the microRNA gene dro-MIR432, likely involved in sex switching. The recent emergence of this miRNA-mediated ZZ/ZW system, distinct from the XY/XX system within Dioscorea, underscores the dynamic evolution of plant sex determination.

plant biology↗

bioRxiv2026

An immune receptor pair consisting of NLR and MLKL confers stable resistance against Pyricularia oryzae pathotype Eluesine on wheat by recognition of three effectors

Kinase fusion proteins (KFPs) have emerged as an important group of immune receptors encoded by plant resistance genes. Here, we report a new type of gene pair that controls resistance of wheat to the blast fungus, Pyricularia oryzae. We cloned a fungal gene involved in avirulence of P. oryzae pathotype Eleusine on wheat and designated it PWT8. We also identified its corresponding resistance gene in wheat, and tentatively named it Rwt8. This resistance gene was located at the same locus as previously identified resistance genes Rwt3 and Rwt6. Molecular cloning revealed that Rwt3, Rwt6, and Rwt8 were the same gene consisting of an identical gene pair, one encoding an NLR and the other encoding a mixed lineage kinase-like (MLKL) protein. These two genes were closely linked in a head-to-head orientation and behaved as a single gene. This gene pair recognized three AVR genes, PWT3, PWT6, and PWT8, and was designated Rwt3.6.8. The distribution of Rwt3.6.8 in common wheat landraces suggested that the gene pair may have been a factor which the D genome provided to the genus Triticum to broaden its adaptability to various environments in the world, especially in Asia and Africa.

plant biology↗

bioRxiv2026

A Tripartite Co-culture System Reveals Defensive Mutualism Between a Nanobdellati Symbiont and Its Host

Archaeal symbioses remain among the least understood cellular interactions. Ultra-small Nanobdellati (initially called DPANN) archaea rely on larger hosts for survival, yet their effects on host eco-physiology and their interactions with infecting viruses have not yet been examined experimentally. Here, we established the first stable tripartite co-culture comprising a Nanobdellales symbiont (YN4), its archaeal host (YN4HA), and a virus (MTIV4). We analyzed this system using physiological, genomic, transcriptomic, glycoproteomic, and cryo-electron tomography (cryoET) approaches. CryoET analysis revealed that the Nanobdellales archaeon formed cone-like structures to contact the host, as has been observed in other Nanobdellati-host systems. In this system, the host is infected by the virus. The Nanobdellales archaeon mitigated virus-induced growth inhibition of the host without any detectable fitness cost, indicating a defensive mutualism rather than a strictly parasitic relationship. This protective effect may involve Nanobdellati-driven remodeling of host cell surface glycans, suggesting a previously unrecognized glycan-mediated defense strategy. Overall, our tripartite system provides new insight into complex archaeal interactions in extreme environments that cannot be captured through conventional binary co-culture systems.

microbiology↗

bioRxiv2026

Evolutionary insights into glucose production in vertebrate development: new findings from Arctic lamprey (Lethenteron camtschaticum)

Glucose has important roles in the development of the hematopoietic stem cells and the brain in vertebrate embryos; however, in most oviparous animals, the amount of glucose in the yolk is scarce. In zebrafish, gluconeogenesis takes place in the yolk syncytial layer (YSL), an extraembryonic tissue that surrounds the yolk. Gluconeogenic activity have also been observed in extraembryonic YSL-like tissue or endoderm-derived tissues in cloudy catshark, sterlet, and western clawed frog during development. However, it remains unclear when such ability was acquired or how it changed over the evolution of vertebrates. In this study, we used the Arctic lamprey, a cyclostome sister group of jawed vertebrates, to compare changes in metabolite levels and gluconeogenic gene expression patterns during development. Also, gluconeogenic activity was assessed using 13C-labeled substrates. Our metabolite analysis revealed that glucose levels increased during development and that glycerol was actively metabolized to produce glucose. In addition, many gluconeogenic genes were expressed in the muscle, notochord, and epithelium, making a striking contrast to previous observations in the above-mentioned vertebrates. Genomic DNA sequence motif analysis using HOMER and MEME identified common transcription factors binding motifs in the upstream regions of g6pc1/2 and fbp1 across vertebrate lineages. Among them, interestingly, the binding motif for HNF4A was not detected in g6pc1/2 and fbp1 genes of cyclostomes, suggesting distinct transcriptional regulation of gluconeogenesis in cyclostomes. These results indicate that gluconeogenesis is an essential process during development across vertebrate lineages, including cyclostomes, although the tissues and regulatory mechanisms for this function vary among lineages.

developmental biology↗

bioRxiv2026

Preserved Intrinsic Neural Timescale Organization with Hierarchical Variation in Autism Spectrum Disorder

Intrinsic neural timescales (INTs) index the temporal decay of neural activity and form a cortical hierarchy from fast sensorimotor to slow transmodal regions. Altered INTs have been reported in autism spectrum disorder (ASD), but it remains unclear whether the hierarchical organization is preserved and how individual variability along this hierarchy relates to sensory traits. Using resting-state fMRI from 182 participants (67 ASD, 115 typically developed controls (TDC)), we estimated INT at each cortical vertex from the autocorrelation half-life and averaged these values across four five-minute runs per participant. Vertex-wise INTs were then averaged within predefined cortical parcels and large-scale functional networks for subsequent analyses. The cortical INT hierarchy was preserved in ASD, showing comparable sensorimotor-to-transmodal hierarchy in both groups. However, regions operating at longer timescales showed prolonged INTs in ASD, and such tendency increased systematically along the hierarchy. No vertex, parcel, or network survived correction of multiple comparisons, indicating that observed alterations followed a distributed hierarchical trend rather than a focal pattern. To disentangle group-level differences from inter-individual variability, we next modeled each participants parcel-wise INT profile relative to a TDC-derived group-averaged template. At the individual level, decomposition of INT profiles revealed that global shifts and hierarchical scaling primarily reflected demographic variation (plimarily sex) rather than diagnostic group membership. After accounting for these components, residual deviations from theTDC-derived cortical INT hierarchy showed a modest association with sensory traits characterized by reduced sensory registration. Together, these findings indicate that while the large-scale hierarchical organization of cortical temporal dynamics is largely preserved in ASD, individual-specific deviations from this hierarchy may contribute to variability in sensory experience beyond group-level differences. HighlightsO_LIAcross both autism spectrum disorder (ASD) and typically developed controls (TDC), intrinsic neural timescales (INTs) followed the established sensory cortical hierarchy and showed a negative association with cortical microstructural markers (myelin content and neurite density index), with no group difference in hierarchical slope. C_LIO_LIAt the whole-brain level, the hierarchical organization of INTs was preserved across ASD and TDC, although regions operating at longer timescales exhibited relatively greater extension in ASD. C_LIO_LIGlobal shifts and hierarchical scaling, describing individual positioning within the INT-based cortical hierarchy, were more strongly associated with demographic variation (primarily sex) than with diagnosis. C_LIO_LIAfter accounting for these global and hierarchical components, residual deviations from the INT-based cortical hierarchy were modestly associated with sensory traits characterized by reduced sensory registration. C_LI

neuroscience↗

bioRxiv2025

Evolution of HMA-integrated tandem kinases accompanied by expansion of target pathogens

Tandem kinase proteins (TKPs) are an emerging family of plant intracellular immune receptors that offer potential for developing novel disease resistance. We cloned Rmo2 and Rwt7, genes for resistance to the blast fungus, from barley and wheat, respectively, and discovered that they are orthologs encoding TKPs with an integrated N-terminal heavy metal-associated (HMA) domain. Rmo2 was collocated with Rpg1, a TKP gene for resistance to stem rust, while Rwt7 was collocated with WTK4, a TKP gene for resistance to powdery mildew. Domain swapping suggested that the HMA domain determines target effector specificity of these genes. We propose a model illustrating an evolutionary process in which a TKP gene has differentiated into paralogs and orthologs that recognize various effectors through diversification of their HMA domains.

plant biology↗

bioRxiv2025

COFFEE-PRESC: A fast pre-screening method using compound retrieval by pairwise positional relationship of representative fragments

Protein-ligand docking is one of the most widely used methods in structure-based virtual screening in the early stages of drug discovery. Its calculations require approximately one minute per compound, making exhaustive evaluation of ultra-large libraries containing billions of molecules computationally impractical. In this study, we propose COFFEE-PRESC (COmpound Filtering by Fragment pair-based Efficient Evaluation for PRE-SCreening), a fast, fragment-based pre-screening method. COFFEE-PRESC first docks fragments in a pre-constructed fragment set to the target protein and enumerates multiple favorable protein-fragment docking poses and then pairs them to consider pairwise positional relationship. The fragment set is composed of a small number of representative fragments that exhibit high similarity to many other fragments, enabling coverage of a large and diverse chemical space. Compounds that contain stuructures similar to fragment pairs are then retrieved through similarity-based searches. This retrieval methodology guarantees that the mutual positional relationship of the two matched fragments does not spatially collide. Finally, the retrieved compounds are evaluated using docking scores of the representative fragments and similarity values between the representative and individual fragments matched in the compound retrieval process. COFFEE-PRESC was 32-fold faster while higher accuracy than Spresso, a existing pre-screening tool, highlighting its potential for application to ultra-large compound library screening. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=111 SRC="FIGDIR/small/692874v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@c9a5eborg.highwire.dtl.DTLVardef@abeddcorg.highwire.dtl.DTLVardef@18d0bfdorg.highwire.dtl.DTLVardef@10e1e33_HPS_FORMAT_FIGEXP M_FIG TOC Graphic C_FIG

bioinformatics↗

bioRxiv2025

Selective induction by statins of FAM134B-mediated sarcoplasmic reticulum (SR)-phagy degrades the SR calcium pump SERCA1 and contributes to myopathy

Statins, HMG-CoA reductase inhibitors, are the most prescribed medication for lowering low-density lipoprotein cholesterol. Although statin intolerance due to statin-associated muscle symptoms (SAMS) has been a clinically important issue for decades, the molecular mechanisms of statin myopathy remain incompletely understood. To seek to clarify how statins induce myopathy, here we perform transcriptome analysis and identify FAM134B short isoform (FAM134B-S), an endoplasmic reticulum (ER)-phagy receptor, as a statin-inducible gene. FAM134B-S expression is regulated by the mevalonate pathway and sterol regulatory element-binding proteins. We further show that FAM134B plays a critical role in the regulation of skeletal muscle integrity both in the steady-state and statin-treated conditions in human iPS cell-derived myocytes and mice. Mechanistically, FAM134B-S interacts with the sarcoplasmic reticulum (SR) calcium pump SERCA1 and promotes its autophagic degradation. Collectively, our work reveals a hitherto undisclosed mechanism of statin myopathy; blocking the mevalonate pathway induces SERCA1 degradation through FAM134B-mediated SR-phagy, exerting myotoxicity.

pharmacology and toxicology↗

bioRxiv2025

Genomic prediction models based on a large-scale recombinant population allow quick breeding of high-yield rice

Rapid development of cultivars with optimal genome-wide allele combinations is essential for addressing agricultural challenges. However, constructing desired genotypes through conventional cross-breeding requires many generations, calling for a more efficient methodology. Here, we present a rapid breeding strategy that combines a large-scale recombinant population as starting material with interpretable genomic prediction models trained on that population. This approach enables efficient construction of target genotypes optimized for multiple traits in cultivars. To validate our strategy in rice (Oryza sativa), we established a nested association mapping population of 2,787 recombinant inbred lines derived from an elite cultivar 'Hitomebore' and 19 diverse donors. We built highly accurate genomic prediction models using this population. We then used the models to estimate haplotype-specific effects and account for trade-offs among yield-related traits, and selected optimal lines and designed breeding schemes. Crossbreeding based on these schemes produced rice lines with the target genotypes for multiple yield-related traits, supporting the predicted effects and validating the effectiveness of our strategy. This genomic breeding approach provides a general framework for rapidly breeding cultivars able to meet the challenges posed by a changing environment.

genetics↗

bioRxiv2025

Locations of consecutive G·C base-pairs direct genomic nucleosome positioning

The nucleosome is a structural and functional subunit of chromatin, and its positioning and dynamics in the eukaryotic genomes serves as a key platform for gene regulation. Here, we determine the positions of fully wrapped nucleosomes across the yeast genome by chemical mapping through the histone H2A-A122C residue, which cleaves near the DNA entry/exit sites. This approach reveals the most refined sequence-dependent profile of nucleosomes reported to date. Comparison of H2A-A122C with the H3-Q85C and H4-S47C methods clearly shows a sequence preference for the chemical cleavage site, and mapping results suggest that the nucleosome locations are dynamic in vivo. More importantly, we find that the depletion of CC and GG dinucleotides at nucleotide positions -11 to -9 and +9 to +11 bp, respectively, from the nucleosome dyad position (0) is inextricably associated with the enrichment of AA/AT/TA/TT dinucleotides in both yeast and mouse genomes. Introducing consecutive C*G base pairs to the corresponding sites in the 601 sequence shifts the nucleosomes to less frequent positions without altering thermal stability, implying a structural constraint imposed by DNA sequence. Thus, CC and GG dinucleotides in the major groove blocks at superhelix locations (SHL) -1.0 and +1.0, respectively, destabilize histone-DNA interactions, serving as intrinsic determinants of nucleosome positioning in eukaryotic genomes.

molecular biology↗

bioRxiv2025

DECREASE IN DNA METHYLATION 1-mediated epigenetic regulation maintains gene expression balance required for heterosis in Arabidopsis thaliana

Heterosis, or hybrid vigor, is characterized by superior phenotypic performance in F hybrids compared to their parental lines, and its expression is influenced by both genetic and epigenetic factors. In this study, we investigated the role of epigenetic regulation, particularly DNA methylation mediated by DECREASE IN DNA METHYLATION 1 (DDM1), in early seedling biomass heterosis using hybrids between Arabidopsis thaliana accessions Columbia-0 and C24. Loss of DDM1 function in F hybrids resulted in a significant reduction of rosette diameter, confirming that DDM1 is essential for heterosis. Transcriptomic and epigenomic analyses revealed extensive genotype-specific changes in gene expression and DNA methylation patterns in ddm1 mutants. Notably, ddm1-F hybrids exhibited upregulation of genes categorized into xyloglucan:xyloglucosyl transferase activity and downregulation of genes categorized into circadian rhythm, which may contribute to reduced growth vigor. Whole-genome bisulfite sequencing showed widespread hypomethylation in ddm1 mutants, yet the overlap between differentially methylated and expressed genes was limited, suggesting indirect or context-dependent regulatory effects. Additionally, we examined the role of salicylic acid (SA) in heterosis using SA-deficient mutants and found that variations in endogenous SA levels did not correlate with biomass heterosis under normal conditions. Our findings suggest that heterosis in A. thaliana is dependent on the maintenance of parental epigenetic divergence, particularly in DNA methylation patterns mediated by DDM1. Disruption of DDM1 compromises this epigenetic complementarity, leading to transcriptomic imbalances that reduce heterosis. HighlightLoss of DDM1 reduces biomass heterosis in Arabidopsis thaliana hybrids by disrupting DNA methylation and transcriptome stability, revealing a novel salicylic acid-independent epigenetic mechanism.

plant biology↗

bioRxiv2025

Discovery and genomics of H2-oxidizing/O2-reducing Deferribacterota ectosymbiotic with protists in the guts of termites and a Cryptocercus cockroach

Members of the phylum Deferribacterota inhabit diverse environments, but their symbiosis with protists has never been reported. We discovered an ectosymbiotic clade of Deferribacterota specifically associated with spirotrichonymphid protists in the guts of the termites Reticulitermes speratus and Hodotermopsis sjostedti and trichonymphid protists in the gut of the wood-feeding cockroach Cryptocercus punctulatus. The ectosymbiotic Deferribacterota were spiral shaped and attached to 16-91% of the host protist cells. These formed a monophyletic cluster within an uncultured insect gut-associated family-level clade, which is sister to the vertebrate gut-associated family Mucispirillaceae. The complete genome of an ectosymbiotic Deferribacterota was obtained from a Trichonympha acuta cell in a C. punctulatus gut and analyzed together with a single-cell amplified genome of another ectosymbiotic Deferribacterota associated with Holomastigotes sp. in the gut of R. speratus. Genome analyses suggest that these Deferribacterota ferment monosaccharides and conduct fumarate and oxidative respiration with H2 as an electron donor. They thus possibly contribute to the removal of hydrogen and oxygen to protect the fermentative activity of the protist hosts. The ectosymbionts possess reduced signal transduction gene repertoires, implying that the association has provided a relatively stable environment for these bacteria. The ectosymbionts likely possess flagella with an unusually expanded number of flagellin variants up to 40, which may reflect an adaptation to their ectosymbiotic lifestyle. We propose a novel genus, Termitispirillum, for these ectosymbionts and a novel family, Termitispirillaceae, for the insect-gut clade, under SeqCode. Our findings provide new insights into the ecology and evolution of Deferribacterota.

microbiology↗

bioRxiv2025

Multipartite coevolution shapes plant apoplastic immunity against rice blast fungus

{beta}-1,3-glucan-binding proteins (GBPs) play crucial roles in cell wall integrity, host- pathogen interactions, and stress responses in fungi, making them essential for fungal survival and virulence. Here, we show that a GBP of the causal agent for blast fungus, Magnaporthe oryzae, is involved in multipartite coevolutionary arms race with rice (Oryza sativa). The rice thaumatin-like pathogenesis-related protein 5 (OsPR5) binds to M. oryzae GBP and sequesters it from the fungal cell wall to confer immunity, but this interaction is counteracted by thaumatin-binding proteins secreted by the fungus to suppress apoplastic immunity. Moreover, a rice receptor kinase located at the cell surface has evolved a thaumatin-like domain to detect the fungal GBP and activate immunity. Our findings reveal that GBPs and thaumatin-domain-containing proteins are engaged in intricate coevolutionary dynamics in the rice apoplast. Given the conservation of thaumatin across plants, we propose a general defense mechanism against fungal pathogens.

plant biology↗

bioRxiv2025

STT3A is required for recognition of pathogen-derived sphingolipids in Arabidopsis

Plants recognize pathogen-associated molecular patterns (PAMPs) via pattern recognition receptors, leading to the activation of pattern-triggered immunity in response to pathogen attack. Phytophthora infestans ceramide D (Pi-Cer D) is a sphingolipid from the oomycete pathogen P. infestans. Pi-Cer D is cleaved by the plant extracellular ceramidase NEUTRAL CERAMIDASE 2 (NCER2), and the resulting 9-methyl-branched sphingoid base is recognized by the plant receptor RESISTANT TO DFPM-INHIBITION OF ABSCISIC ACID SIGNALING 2 (RDA2) at the plasma membrane to transduce a defense signal. However, additional components are likely involved in sphingolipid recognition, which remain to be identified. Here, we employed a screen based on Lumi-Map technology to look for Arabidopsis (Arabidopsis thaliana) mutants with altered defense responses to Pi-Cer D. We identified three mutants showing diminished responses to Pi-Cer D and elf18, each carrying mutations in STAUROSPORIN AND TEMPERATURE SENSITIVE 3-LIKE A (STT3A), which encodes an oligosaccharyltransferase. The stt3a mutants exhibited higher susceptibility to the pathogen Colletotrichum higginsianum than the wild type and displayed alterations in NCER2 protein modifications. These findings suggest that STT3A contributes to plant immunity via post-translational modification of proteins including NCER2.

plant biology↗

bioRxiv2025

Fine-tuning quantitative agronomic traits by manipulating gene copy number in rice

Although recent plant pan-genome studies have revealed extensive copy number variations, there are limited studies addressing the phenotypic consequences of these variations. Here, we manipulated the copy number of OsMADS18 in rice (Oryza sativa) through gene editing and evaluated the effects. OsMADS18, which encodes a MADS-box transcription factor known to regulate plant development, is tandemly duplicated in the elite rice cultivar Hitomebore as a natural variant. We therefore edited the OsMADS18 copy number using a basic CRISPR/Cas9 system and established rice lines harboring one to three tandem copies of OsMADS18, as identified through high throughput qPCR screening. The presence of one to three OsMADS18 tandem copies was reflected in stepwise increases in transcript levels and concomitant trait values for leaf blade length and culm length. These results demonstrate that manipulating gene copy number can fine-tune important agronomic traits, providing a novel breeding strategy for crop improvement.

plant biology↗

bioRxiv2025

Whole-genome sequencing reveals the molecular basis of sex determination in the dioecious wild yam Dioscorea tokoro

Dioecious plants, which have distinct male and female individuals, constitute [~]5% of angiosperm species and have emerged frequently and independently from hermaphroditic ancestors. Although recent molecular studies of sex determination have started to reveal the diversity of the genetic systems underlying dioecy, research on the evolution of dioecy is limited, especially in monocots. Here, we describe the molecular basis of sex determination in the monocot Dioscorea tokoro, a dioecious wild yam endemic to East Asia. Chromosome-scale and haplotype-resolved genome assemblies and linkage analysis suggested that this plant has a male heterogametic sex determination (XY) system, with sex determination regions located on chromosome 3. Sequence read coverage analysis of the sex chromosomes revealed X- and Y-specific regions in putative pericentromeric chromosome regions. Within the Y-specific region, we identified two candidate genes that are likely involved in sex determination: BLH9, encoding a homeobox protein, and HSP90, encoding a molecular chaperone. BLH9 has similar functions to AtBLH9 in Arabidopsis thaliana. BLH9 is thought to suppress female organ development, whereas HSP90 might be required for pollen development. These results shed light on the complex evolution of dioecy in plants. Author summarySexual reproduction is a nearly universal, indispensable feature of evolution in eukaryotes. The molecular mechanisms underlying sex determination vary depending on the taxon. However, most information about this process was derived from studies of model organisms and/or domesticated species. To elucidate the diversity and evolution of sex determination, we need to expand the taxonomic breadth of these investigations. Here, we focused on the monocot genus Dioscorea, which contains species with multiple sex-determination systems, suggesting that frequent evolutionary transitions occur between the different sex-determination systems. We investigated the genetics of sex determination in Dioscorea tokoro, a dioecious wild yam endemic to East Asia. Whole-genome assembly and genetic analysis, along with transcriptome analysis, suggested that this species employs a male heterogametic sex determination (XY) system, with two Y-chromosome-specific genes that might be involved in male and female differentiation. These findings enhance our understanding of the complex evolution of dioecy.

plant biology↗