Nested within the Archaeplastida kingdom is an ancient eukaryotic phylum called the Rhodophyta or red algae. With over 7,500 species currently recognised, the red algae form the largest group of marine macroalgae and were among the first eukaryotic lineages to evolve multicellularity. Despite their shared ancestry with land plants, complex developmental programs, and major ecological and agronomic importance, our molecular understanding of red algal biology remains underexplored.

To address this, we are actively developing Bostrychia mortiziana - a prominent member of the most diverse and morphologically complex Ceramiales order - as a tractable model system to study red algal development and reproduction.

We recently generated a chromosome-level genome assembly for Bostrychia and showed that genomic expansion is a common feature of red algal evolution, challenging the prevailing view that red algal genomes are typically small (~100 Mb). Notable innovations include genomic expansion driven by giant DNA transposons, amplification of gene families involved in signalling and transcriptional regulation, and expanded gene-rich UV sex chromosomes that harbor deeply conserved TALE-HD transcription factors known to regulate life cycles across eukaryotes.

A central question we are currently pursuing is how the characteristic triphasic life cycle of red algae is regulated at the molecular level. Using epigenomics and transcriptomics, we are beginning to map the gene regulatory networks and specialised differentiation programs that orchestrate transitions in the complex triphasic life cycle.

Together, our findings offer a unique perspective of the genomic adaptations underpinning red algal diversity and position Bostrychia as a powerful model system to study the evolutionary origins and general principles of reproductive and developmental complexity in red algae.

理学部2号館講堂

東京大学大学院理学系研究科・生物科学専攻・発生細胞生物学研究室