Lukthallusinasjoner

Lukthallusinasjoner are a class of microscopic symbiotic associations identified primarily in temperate forests. The term derives from the Norwegian word *luke* meaning “hole” or “gap”, the botanical term *thallus* referring to a simple plant body, and the suffix *-inasjoner* suggesting an active process or interaction.

Morphologically, a lukthallusinasjon consists of a filamentous fungal thallus that infiltrates the intercellular spaces of a host bark or leaf tissue. The fungal partner typically belongs to the Ascomycota phylum, while the host is usually a broad‑leaf hardwood such as oak or beech. In contrast to classic mycorrhizae, the fungal hyphae do not penetrate the plant cell wall but instead occupy the extracellular matrix, forming a transient “gap” within the vascular cortex.

Functional studies indicate that lukthallusinasjoner contribute to nutrient exchange by enhancing the uptake of micronutrients such as phylloquinone and iron. They also play a role in pathogen resistance, as the fungal presence can induce defensive gene expression in the host. The phenomenon has been documented in approximately thirty species across Europe and North America, with a few isolated reports from East Asia.

Despite its ecological relevance, the precise molecular mechanisms governing the establishment of lukthallusinasjoner remain under investigation. Recent genomic approaches have begun to elucidate signaling pathways involved in host recognition and hyphal colonization. Further research is expected to clarify the potential application of these associations in forest management and bioremediation.