2026 vol67 (8)

Plant & Cell Physiology

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While dibenzylbutyrolactone lignans (DBLs) produced from various plants are levorotatory, members of the Thymelaeaceae family, which includes many medicinal and ornamental plants, have been observed to produce dextrorotatory DBLs. Until now, the mechanism underlying the production of dextrorotatory DBLs has remained entirely unknown. In this issue, however, Tutihashi et al. demonstrate that the selectivity of the substrate enantiomers of the two enzymes involved in DBL production—pinoresinol/lariciresinol reductase and secoisolariciresinol dehydrogenase— determines the production of dextrorotatory and enantiomerically pure DBLs in Daphne genkwa (lilac daphne in English, fujimodoki in Japanese), a member of the Thymelaeaceae family.

The cover image shows flowers of D. genkwa.
Photo credit: Dr. Toshiaki Umezawa, Research Institute for Sustainable Humanosphere, Kyoto University, Japan.

Research Highlight: First authors

Co-regulation of germination and gemma dormancy in liverworts

Dormancy enables plants to survive unfavorable environments, but its regulation in bryophyte propagules remains unclear. Yoshimura, Kato et al. have identified MpHYPNOS as a central regulator of gemma dormancy in Marchantia polymorpha. MpHYPNOS suppresses germination via ABA-independent cell-cycle repression and promotes ABA-dependent desiccation tolerance. This dual control provides insight into the evolution of dormancy as an adaptation to terrestrial environments. See also Commentary by Morinaka, in this issue.

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Nami Yoshimura

Nami Yoshimura is a Ph.D. candidate interested in the molecular mechanisms, origin, and evolution of dormancy in plants. Her research focuses on dormancy in vegetative propagules using the liverwort Marchantia polymorpha as a model system. She is particularly interested in how dormancy mechanisms evolved in relation to plant adaptation to terrestrial environments. Outside of research, Nami enjoys listening to music and watching sports.

Co-regulation of germination and gemma dormancy in liverworts

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Hirotaka Kato

Hirotaka Kato is an Associate Professor at Ehime University, Japan. He previously conducted research at Wageningen University in the Netherlands as an EMBO Long-Term Fellow. He has studied the origin and evolution of auxin signaling, primarily using the liverwort Marchantia polymorphaas a model system. His research has focused on understanding how this fundamental hormonal pathway contributed to the evolution of developmental regulation in land plants. While continuing his studies on developmental regulation in M. polymorpha, he has recently expanded his research to the non-model fern Equisetum arvense (common horsetail) to investigate how developmental control mechanisms evolved across land plants.

Social media handle:

X: @HirotakaKato_EU
Bluesky: @hirotakakato.bsky.social

A methyltransferase that regulates liverwort development

Methylation is a common enzymatic modification for many plant hormones and secondary metabolites. Kawamura et al. showed that a SABATH methyltransferase regulates growth and sexual reproduction in Marchantia polymorpha, in association with gibberellin-related metabolism. The liverwort-specific origin of this enzyme highlights how metabolic enzymes have been repeatedly recruited to regulate development during land plant evolution. See also Commentary by Hisanaga, in this issue.

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Shogo Kawamura

Shogo Kawamura specializes in plant molecular biology and bioinformatics. He received his Ph.D. from Kyoto University in 2023, supported by a JSPS Fellowship. His major research achievements include the development of the databases MarpolBase and MapolBase Expression (MBEX), and investigations into the gibberellin-related pathway in Marchantia polymorpha. He has also contributed to studies on far-red light responses and deep-learning analysis of morphological traits. Currently, a researcher and engineer at Preferred Networks, Shogo applies machine learning while continuing liverwort research. Outside of work, he enjoys playing Go, board games, and good drinks.

Specialized metabolite composition of liverwort oil bodies

Liverwort oil bodies accumulate specialized metabolites involved in chemical defense, but how their accumulation is controlled remains unclear. Kanazawa et al. have examined the oil body membrane-localized ABCG transporters MpABCG1 and MpABCG36 in Marchantia polymorpha. Both were found to contribute to sesquiterpene accumulation, while MpABCG1 also promotes marchantin accumulation. Thus, ABCG transporters help establish the specialized metabolite composition of oil bodies in liverworts.

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Takehiko Kanazawa

Takehiko Kanazawa is an Assistant Professor in the Division of Cellular Dynamics at the National Institute for Basic Biology, Japan. He received his Ph.D. from the University of Tokyo in 2017, where he studied membrane trafficking in plant cells. His research focuses on the mechanisms and evolution of organelle biogenesis, particularly how conserved membrane-trafficking systems are repurposed to generate lineage-specific organelles such as liverwort oil bodies. Outside the laboratory, Takehiko enjoys playing the piano, which provides both a creative outlet and a refreshing break from research.

tRNA thiolation in uORF-regulated mRNA translation

Thermospermine represses vascular xylem formation by regulating the translation of specific mRNAs containing a conserved upstream open reading frame (uORF). Nishii et al. have identified a suppressor mutant of an Arabidopsis dwarf mutant defective in thermospermine biosynthesis. The causal mutation is a loss-of-function allele of CTU2, which encodes a tRNA thiolation enzyme important in the biosynthesis of the wobble uridine modification 5-methoxycarbonylmethyl-2-thiouridine. Further genetic analyses suggest that tRNA modification plays a critical role in uORF-mediated translational regulation of key regulators important for xylem development.

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Yuichi Nishii

Yuichi Nishii investigated the molecular genetic mechanisms underlying thermospermine-mediated regulation of vascular xylem differentiation in Arabidopsis and received a Ph.D. from the Graduate School of Environmental, Life, Natural Science and Technology at Okayama University. After completing the doctoral program, he joined a forensic science laboratory, where he applies biological expertise to support criminal investigations. In the future, Yuichi hopes to build on this research experience in plant science to conduct innovative research in the field of forensic botany.

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