Through the Shot Glass: Secrets Hidden in Liverworts

Investigating plant vegetative reproduction is essential for enhancing crop yield and advancing bioengineering. Kobe University research is advancing in the investigation of genetic regulation in liverworts, which serve as exemplary model plants and potential candidates for space agriculture.

Potatoes are tubers, while ginger is a rhizome; both represent modes of vegetative plant reproduction, wherein plants produce structures that can give rise to genetically identical individuals. This reproductive mode is crucial for agriculture and horticulture; nevertheless, research on the underlying genetic mechanisms is scarce. Kobe University plant geneticist ISHIZAKI Kimitsune considers the liverwort Marchantia polymorpha to be an exemplary model organism for studying this process. Over the past decade, he has engaged in decoding its genome and developing techniques for its efficient genetic manipulation. He said, “Also, the liverwort is so proliferative that it is considered a nuisance to gardeners, growing back quickly no matter how often it is removed.”

The liverwort propagates via diminutive, detachable buds known as “gemmae,” which develop in small cups on the upper surface of the liverwort’s “leaves” and are disseminated by precipitation, wind, or fauna. Additionally, the plant participates in sexual reproduction, transitioning from vegetative reproduction when the days lengthen in summer. “In prior research, we identified a gene that appeared to be implicated in the development of both gemma cups and the plant’s sexual reproductive structures.” However, its function remained entirely ambiguous, prompting our desire for further understanding,” states Ishizaki.

The Kobe University team reports in the journal New Phytologist that plants deficient in the gene typically do not develop vegetative or sexual reproductive organs, and in exceptional instances, produce empty, shot-glass-shaped cups instead of the typically broad and shallow gemma cups, prompting them to designate the gene as “SHOT GLASS.” This indicates that the gene is essential for the formation of functional reproductive structures. Upon examining the interactions with other implicated genes, researchers discovered that SHOT GLASS functions by inhibiting the formation of air chambers in the liverwort’s “leaves” to facilitate gemma cup development, while also assisting in the proper localisation of factors essential for the development of sexual reproductive organs.

Moreover, Ishizaki and his team discovered something remarkable. They recognised that flowering plants, which exhibit greater complexity than the rudimentary liverwort, possess genes associated with SHOT GLASS, possibly originating from a common ancestral gene of all terrestrial plants. Notably, in blooming plants, those genes also have a role in regulating the development of the secondary meristem, which generally facilitates branch growth. Upon inserting the liverwort gene into a flowering plant that lacks a corresponding variant, researchers discovered that it can compensate for the deficiency left by its more evolved relative. Ishizaki explains, “This suggests that the mechanism by which plants create new buds away from the main shoot tip may be common to all land plants.”

This indicates that Ishizaki’s liverwort serves as an advantageous model organism for investigating this agriculturally significant process. However, the researcher from Kobe University harbours grander aspirations. “In contrast to crop plants, liverworts do not necessitate soil and can be cultivated solely through fog cultivation.” We are investigating the cultivation of liverworts as a comprehensive food supply. Ishizaki elucidates that it might potentially serve as a food source in space. He states: “We are also investigating the utilisation of liverworts as organisms for the bioproduction of valuable chemical resources, which has thus far been largely confined to bacteria and yeasts.” The engineering technologies we are building and the knowledge we are acquiring regarding the plant’s biology represent a significant advancement in that direction.

This research received funding from the Ministry of Education, Culture, Sports, Science and Technology of Japan (grants 25119711, 15H01233, 17H06472, 21K15125, 19H05673, 19H05670, 20H05780), the Japan Society for the Promotion of Science (grants 21J40092, 15H04391, 19H03247, “Program for forming Japan’s peak research universities (J-PEAKS)”), the Japan Science and Technology Agency (grant JPMJGX23B0), the SUNTORY Foundation for Life Sciences, the Yamada Science Foundation, the Asahi Glass Foundation, the Kyoto University Foundation, and the Ohsumi Frontier Science Foundation. The study was executed in partnership with experts from Kyoto University and Ehime University.

Kobe University is a national institution with origins tracing back to the establishment of the Kobe Higher Commercial School in 1902. It is currently one of Japan’s premier comprehensive research institutions, with almost 16,000 students and approximately 1,700 teachers across 11 faculties and schools, as well as 15 graduate schools. Kobe University integrates social and natural disciplines to develop leaders with an interdisciplinary outlook, generating knowledge and promoting innovation to tackle societal concerns.

Original Publication
Journal: New Phytologist
DOI: 10.1111/nph.70337
Method of Research: Experimental study
Subject of Research: Cells
Article Title: SHOT GLASS, an R2R3-MYB transcription factor, promotes gemma cup and gametangiophore development in Marchantia polymorpha
Article Publication Date: 30-Jul-2025