Mycorrhizal fungi use RNA to stimulate root colonization.

Researchers have identified a molecular mechanism that enhances the formation of arbuscular mycorrhizae in plant roots. The fungus Rhizophagus irregularis It transfers small RNA molecules to plant cells. This genetic material alters the activity of plant genes and promotes root colonization.

The research demonstrates the occurrence of RNA interference between different organisms, known as cross-kingdom RNA interference. The process has already appeared in interactions between plants and pathogens. Now the data indicate its role in a beneficial symbiosis as well.

Arbuscular mycorrhizae emerged approximately 450 million years ago. The system involves fungi from the Glomeromycotina group. These microorganisms colonize the roots of approximately 80% of terrestrial plants. This association enhances plant nutrition and improves crop performance.

Fungi capture mineral nutrients from the soil. Hyphae transport these elements to the root. Highly branched structures called arbuscules release the nutrients into the cells of the root cortex. In return, the plant provides carbon in the form of sugars and lipids.

Interaction analysis

The team analyzed the interaction between Rhizophagus irregularis and the model legume Lotus japonicusScientists investigated small RNA molecules present in a cellular complex called AGO1, linked to gene silencing. The analysis revealed RNA molecules originating from the fungus inside the plant cells.

These small RNAs act on the host plant's genetic regulation system. The process alters the expression of plant genes. This change favors the establishment of mycorrhizae and expands root colonization.

The authors indicate that RNA communication between organisms functions as a novel regulatory mechanism for mycorrhizal symbiosis. This finding broadens the understanding of interactions between plants and soil fungi.

Knowledge can guide strategies aimed at sustainable agriculture. Arbuscular mycorrhizae increase nutrient absorption and reduce dependence on mineral fertilizers.

More information at doi.org/10.1038/s41477-026-02247-2