New Type of Symbiotic Relationship Discovered Between Algae and Fungi

Researchers from the Institute of Botany, Czech Academy of Sciences, described the symbiotic relationship between fungi and algae which science has largely overlooked until now. The coexistence of algae and corticioid basidiomycetes, which are common in temperate forests, has been given a new name: alcobiosis.

Jan Vondrák of the Department of Taxonomy, Institute of Botany, and the first author of the study says “Years ago, during field trips, we were repeatedly puzzled to find a layer of green algae where some of the fungal coatings on wood or bark (so-called corticioid fungi) are disturbed. We discovered that this is a close symbiosis of fungi and algae, not a lichen, though, because the fungus does not depend on its alga for nourishment.“

Researchers introduced a new term for this type of coexistence: alcobiosis, formed by letters from the three key words: algae, corticioid fungi and symbiosis.

In the course of several years, the team of researchers gathered a large number of samples and performed DNADNA, or deoxyribonucleic acid, is a molecule composed of two long strands of nucleotides that coil around each other to form a double helix. It is the hereditary material in humans and almost all other organisms that carries genetic instructions for development, functioning, growth, and reproduction. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>DNA sequencing of the algal and fungal partners. They discovered that the symbiosis is very common and occurs in a great many corticioid fungi across the class of agaricomycetes. Individual fungal speciesA species is a group of living organisms that share a set of common characteristics and are able to breed and produce fertile offspring. The concept of a species is important in biology as it is used to classify and organize the diversity of life. There are different ways to define a species, but the most widely accepted one is the biological species concept, which defines a species as a group of organisms that can interbreed and produce viable offspring in nature. This definition is widely used in evolutionary biology and ecology to identify and classify living organisms.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>species are usualy faithful to a specific algal species from a range of algae described in various alcobises.

Ensuing physiological measurements of algal activity in alcobioses confirmed that the algae are alive, active and engage heavily in photosynthesisPhotosynthesis is how plants and some microorganisms use sunlight to synthesize carbohydrates from carbon dioxide and water.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>photosynthesis, which proves that they prosper inside fungal tissue. Alcobioses bear a striking resemblance to lichens, but differ from them in that the fungal partner does not depend on its alga for nourishment.

“And so the main unknown still is in what way this symbiosis is beneficial for each of the partners. However, our discovery also brings many questions related to geographic, ecological and taxonomic parameters of the symbiosis, such as whether alcobioses diversity increases from polar to tropical regions,“ Jan Vondrák comments on the team´s discovery and adds: “This coexistence has been mentioned in articles before. Most often, though, these were just fragmentary comments that such and such species of corticioid fungus is often found together with algae. We were the first to graps alcobioses as a widespread phenomenon which includes a large number of algae and fungi.“

During their research, the authors also discovered that the spread of alcobioses is aided by small gastropods who often feed on corticioid fungi. Their excrements contain viable cells of algae and fungi who give rise to new alcobiotic coating shortly after. This type of reproduction is similar to lichen “isidia“ (i.e., specific lichen thallus structures used in vegetative reproduction).

Scientists at the Institute of Botany have described a symbiotic relationship that is very common in Europe, but which has so far escaped attention, despite the fact that many generations of naturalists have come and gone in Europe. In this way a new space has opened for the further study of alcobioses from various points of view by both professional biologists and biology enthusiasts. For alcobioses are clearly visible to the naked eye and it is easy to distinguish them from similar fungi which do not form this kind of relationship.

Reference: “Alcobiosis, an algal-fungal association on the threshold of lichenisation” by Jan Vondrák, Stanislav Svoboda, Lucie Zíbarová, Lenka Štenclová, Jan Mareš, Václav Pouska, Jiří Košnar and Jiří Kubásek, 28 February 2023, Scientific ReportsEstablished in 2011, <em>Scientific Report</em>s is a peer-reviewed open-access scientific mega journal published by Nature Portfolio, covering all areas of the natural sciences. In September 2016, it became the largest journal in the world by number of articles, overtaking <em>PLOS ON</em>E.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>Scientific Reports.
DOI: 10.1038/s41598-023-29384-4