Alcobiosis, an algal-fungal association on the threshold of lichenisation

• Published in: Scientific reports Vol. 13; no. 1; p. 2957
• Main Authors: Vondrák, Jan, Svoboda, Stanislav, Zíbarová, Lucie, Štenclová, Lenka, Mareš, Jan, Pouska, Václav, Košnar, Jiří, Kubásek, Jiří
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 28-02-2023; Nature Publishing Group; Nature Portfolio
• Subjects: 631/158; 631/1647; 631/181; 631/443; 631/449; Alarmins; Algae; Bark; Biological Transport; Carbon; Carbon dioxide; Chlorophyll; Coevolution; Desmococcus; Eczema; Fungi; Gas exchange; Humanities and Social Sciences; Hyphae; Keratosis; Lichens; multidisciplinary; Mycobionts; Science; Science (multidisciplinary); Symbiosis; Wood
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-023-29384-4

Alcobiosis, the symbiosis of algae and corticioid fungi, frequently occurs on bark and wood. Algae form a layer in or below fungal basidiomata reminiscent of the photobiont layer in lichens. Identities of algal and fungal partners were confirmed by DNA barcoding. Algal activity was examined using gas exchange and chlorophyll fluorescence techniques. Carbon transfer from algae to fungi was detected as
13
C, assimilated by algae, transferred to the fungal polyol. Nine fungal partners scattered across Agaricomycetes are associated with three algae from Trebouxiophycae:
Coccomyxa
sp. with seven fungal species on damp wood,
Desmococcus olivaceus
and
Tritostichococcus coniocybes
, both with a single species on bark and rain-sheltered wood, respectively. The fungal partner does not cause any obvious harm to the algae. Algae enclosed in fungal tissue exhibited a substantial CO
2
uptake, but carbon transfer to fungal tissues was only detected in the
Lyomyces-Desmococcus
alcobiosis where some algal cells are tightly enclosed by hyphae in goniocyst-like structures. Unlike lichen mycobionts, fungi in alcobioses are not nutritionally dependent on the algal partner as all of them can live without algae. We consider alcobioses to be symbioses in various stages of co-evolution, but still quite different from true lichens.