Abstract The International Symposium ‘Microbial Growth and Behavior: From Bench to Nature’ was held as part of the annual meeting of the Society for Genome Microbiology, Japan. This session was designed to highlight challenges in modern microbiology: how to connect molecular insights obtained from laboratory model systems with the dynamic and complex responses of microbes in natural environments.
Atractylodes lancea rhizomes are used as crude drugs. Essential oil compounds, including atractylodin, hinesol, β-eudesmol, and atractylon, are key determinants of crude drug quality. Conventional breeding of A. lancea is difficult because of its perennial growth. In this study, a chromosome-scale reference genome of A. lancea (4.79 Gb) was generated, and genome-wide association studies (GWAS) and genomic predictions of essential oil compounds were conducted to explore the potential for genome-assisted breeding. Genotyping of 480 lines using double-digest restriction-site-associated DNA-sequencing yielded 29,136 high-quality SNPs. All the compounds showed high genomic heritability (h2 = 0.758-0.915), indicating strong genetic control. Despite the high genomic heritability, GWAS detected only one weak association with atractylon and no significant loci for the three compounds. However, genomic prediction achieved moderate to high accuracy across multiple models, particularly the ridge regression, genomic best linear unbiased prediction, and Bayesian approaches. The prediction accuracy, measured as the Pearson correlation coefficient between the observed and predicted values, exceeded 0.6 for all four essential oil compounds. These results demonstrate the efficacy of genomic selection for improving essential oil compound levels in A. lancea and provide a foundation for genome-assisted breeding of medicinal plants with long breeding cycles.
Microalgae are gaining attention as sustainable resources for the production of valuable compounds, including biofuels, pigments, and bioactive metabolites. To support metabolic engineering and genome editing approaches aimed at enhancing these traits, high-quality genome assemblies are essential; however, genomic information remains limited for many microalgal lineages. Tetraselmis sp. NKG400013 is a green alga known for high glycosphingolipid accumulation with distinctive structural features. Here, we report a draft genome assembly of this strain generated using PacBio HiFi sequencing and transcriptome-supported annotation. The assembled genome spans 423.7 Mbp, with 74.5% repetitive sequences and 15,322 predicted protein-coding genes. Comparative analyses across 11 green algal species revealed a positive correlation between genome sizes and repeat contents, indicating that transposable element expansion, particularly long terminal repeat retrotransposons, has substantially contributed to genome enlargement in Tetraselmis. Genome-wide functional annotation and ortholog inference identified core enzymes required for glycosylceramide biosynthesis. Both sphingolipid Δ4 and Δ8 desaturases were identified in Tetraselmis and their coexistence suggests an expanded capacity for long-chain base modification that may underlie its distinctive glycosphingolipid profile. These results establish a genomic framework for understanding the high glycosphingolipid-producing capacity of NKG400013 and provide insights into the evolutionary diversification of sphingolipid metabolism in green algae.
Single-cell RNA sequencing (scRNA-seq) enables high-resolution profiling of individual cells. However, inferring temporal relationships among cells remains a challenge. Here, we present Real-Time Course Analysis (RTCA), a simple direct phylogenetic signal framework that reconstructs cell lineages from somatic variants detected across cells using variants derived from nuclear-encoded transcripts in scRNA-seq data. Our simulations demonstrate that only a modest increase in informative variant sites is sufficient to maintain accurate tree reconstruction, even with a tenfold increase in the number of cells. This scalability makes RTCA applicable to datasets generated by recent single-cell sequencing technologies and is also suitable for reanalyzing existing datasets. We also performed a comparative analysis between our method and a representative genotype-mediated inference framework, PhylinSic, which shares certain conceptual similarities with RTCA. The simulation results show that RTCA is more robust to sparse mutation signals and dropout-induced missing data than PhylinSic. In an application to the datasets from two healthy human placental samples, RTCA successfully reconstructed bifurcating phylogenetic trees. By mapping expression-based cell type clusters onto the trees, we evaluated the degree of monophyly within lineages and found our results consistent with known placental differentiation pathways. The identified cell lineages also aligned with classifications based on gene expression and pseudotime analysis. Compared to gene expression-based and pseudotime analysis, RTCA provides a temporally-based model of cell trajectories, integrating lineage and expression information in a biologically meaningful manner. In summary, RTCA offers a scalable, cost-effective solution for reconstructing developmental processes in complex normal tissues.
Cyclamen is an economically important ornamental plant widely cultivated for its diverse floral characteristics and adaptation to cool climates. Despite its horticultural significance, genomic resources for this species remain limited, hindering molecular studies and genomics-assisted breeding. Here, we report the first highly contiguous nuclear genome assembly of C. persicum generated using high-fidelity long-read sequencing. The assembled genome spans 1.48 Gb, consisting of 126 contigs with an N50 length of 52.3 Mb. Telomeric repeat analysis identified eight contigs containing telomeric sequences at both ends, suggesting the presence of near-complete chromosome assemblies. Genome completeness assessment using BUSCO indicated 98.1% completeness. Repetitive sequences occupied 82.9% of the assembly, with long terminal repeat retrotransposons accounting for 42.1% of the genome. A total of 40,223 protein-coding genes were predicted, with a complete BUSCO score of 95.7%. Comparative orthogroup analysis with five representative eudicot species identified 430 orthogroups specific to C. persicum and 363 orthogroups shared exclusively between C. persicum and Primula kwangtungensis , indicating the presence of both lineage-specific and Primulaceae-conserved gene families. These findings provide critical insights into gene family evolution within Primulaceae and establish an essential comparative framework for future genomic studies. The genome resource presented here provides an invaluable foundation for investigating genome evolution, gene function, and trait-associated loci in cyclamen, effectively facilitating molecular breeding and genetic improvement in this ornamental species. ### Competing Interest Statement The authors have declared no competing interest. Raw sequence reads and assembled sequences are available at DDBJ (BioProject accession number PRJDB42699). The genome assembly and gene annotation files are available in Kazusa Genome Atlas (). JSPS KAKENHI, JP22H05172, JP22H05181, JP24K08899
