Carbon Transfer Between Plants via Mycelial Networks Demonstrated in Cultivation Experiments: Toward Clarifying 'Energy Distribution Between Plants' via Fungi

## Carbon Transfer Between Plants via Mycelial Networks Demonstrated in Cultivation Experiments

A joint research group led by Professor Masahide Yamato of the Chiba University Graduate School of Education and Professor Kenji Suetsugu of the Kobe University Graduate School of Science has elucidated that Gentiana zollingeri, a plant in the Gentianaceae family, acquires carbon compounds from other plants through arbuscular mycorrhizal (AM) fungi using a newly developed cultivation system. The relationship between plants and fungi revealed by this study is expected to provide new perspectives on understanding plant growth strategies and the establishment of plant diversity.

The research results were published online in the international academic journal Mycorrhiza on May 28, 2026.

### Research Background
Most plants live in a symbiotic relationship with fungi called mycorrhizal fungi, providing photosynthetic carbon compounds to the fungi in exchange for nutrients from the soil. On the other hand, some members of the Orchidaceae and Ericaceae families, which mainly live in symbiosis with basidiomycetes, are known as (partially) myco-heterotrophic plants that have lost their photosynthetic ability and rely on carbon compounds from mycorrhizal fungi. In these plants, symbiotic basidiomycetes tend to be richer in the carbon isotope 13C than photosynthetic plants; thus, carbon acquisition from fungi can be estimated by examining the carbon isotope ratio (δ13C value) of plants collected in the field. However, arbuscular mycorrhizal (AM) fungi, which live in symbiosis with many plants, are not as rich in 13C as basidiomycetes. Therefore, it was difficult to clarify carbon acquisition from fungi in (partially) myco-heterotrophic plants that live in symbiosis with AM fungi using only the δ13C values of plants collected in the field. In this study, we utilized the difference in δ13C values—due to C4 plants containing more 13C than C3 plants—as a 'label' to verify carbon transfer between plants via hyphae through cultivation tests.

### Research Highlights
In this study, we constructed U-shaped pots and used a very fine 30 μm nylon mesh to separate the section for cultivating C3 or C4 plants from the section for Gentiana zollingeri. While this mesh allows AM fungal hyphae to pass through, it blocks plant roots, preventing direct root contact. Additionally, the U-shaped structure reduced the influence of 13C-rich carbon dioxide produced by C4 plant root respiration on the δ13C values of Gentiana zollingeri. When we inoculated AM fungi into C3 and C4 plants and cultivated Gentiana zollingeri with them, individuals cultivated with C4 plants showed significantly higher δ13C values than those cultivated with C3 plants. Furthermore, individuals cultivated with C4 plants showed greater growth as their δ13C values increased—that is, the more carbon compounds they received, the more their growth was promoted. This result indicates that carbon compounds move between plants via mycorrhizal fungi and that this heterotrophy contributed to the growth of Gentiana zollingeri.

### Future Prospects
The cultivation experimental system using U-shaped pots developed in this study will enable verification of the presence or absence of carbon transfer between plants via AM fungi in various plant species in the future. If carbon transfer via AM fungi is confirmed in diverse plants, it suggests that the underground mycelial network is not just a nutrient absorption pathway but may also function as a site for 'energy distribution' where carbon compounds move between plants. Such plant-fungal relationships are expected to provide new perspectives on understanding plant growth strategies, ecological niches, and the establishment of plant diversity.