Until now unknown world of mushrooms Only four per cent of all mushrooms so far known

The unknown world of mushrooms
Only about 4 percent of the fungi are scientifically recorded, as a study by scientists at the Botanical Garden and Botanical Museum of the Free University of Berlin and the London Royal Botanic Gardens, Kew and the Natural History Museum found in the course of a study. Around 2.2 to 3.8 million species of fungus are said to exist worldwide. Mushrooms are thus the second largest organism kingdom after the animals, because the fungi exceed the diversity of plants by about 6-10-fold. At least 18 times more mushroom species exist than currently known. The research results were published in the current issue of the journal "Microbiology Spectrum".

One of the big questions of biology has been reworked. In the past, speculation ranged from just over half a million to more than 5 million mushroom species worldwide. Currently, only 120,000 species of fungi are known and scientifically described. That's only about 3 to 8 percent of the estimated global mushroom diversity. Over 2 to 3 million mushroom species are still to be discovered and described. Mushrooms are thus the least studied of the three major organism kingdoms: while plants account for approximately 80% of an estimated 390,000 species, animals account for around 20% of an estimated 7 million.

Variety of mushrooms (Image: Brent Hofacker / fotolia.com)

Collecting the still unknown mushrooms is a monumental task for the researchers, as currently only about 1500 new types of fungi are described each year. So it would take another 1,500 to 2,500 years to describe all unknown types of mushrooms. Or a tenfold of specialists to complete this task within the next two centuries. However, habitat destruction and unsustainable economies have led to a constant decline in fungal diversity globally: many species die out before being discovered.

For the current estimate, the researchers combined three estimation methods. First, they evaluated the latest research data, which is essentially based on DNA sequencing methods. Alone through the analysis of the so-called DNA bar coding were discovered in supposedly known species of fungi (such as fly agaric or the chanterelle) on average about 10 previously unknown species. The already known 120,000 mushroom species could therefore correspond to up to 1.2 million species.

Second, the researchers used analyzes from environmental samples, such as soil or water. Using novel DNA sequencing methods, all existing organisms are recorded. The researchers suspect here at least 1 million additional, unknown species of fungus worldwide, together about 2.2 million. Third, studies at selected locations, where all plant and fungi species were systematically recorded, showed an average of 9.8 species of fungi per plant species. With an estimated total of 390,000 plant species worldwide, this alternative estimation method yields a total of 3.8 million species of fungi.

The researchers suspect many undescribed species of fungus in so-called hotspots such as the tropics, little-studied habitats (including in the symbiotic lichens and insects) and in unprocessed material of natural history collections.

Few mushrooms are known to man. (Image: kichigin19 / fotolia.com)

Mushrooms are present in all ecosystems, even in the sea. The kingdom of mushrooms include single-celled organisms such as baker's yeast as well as the macroscopic fly agaric or lichen fungi. According to current knowledge, fungi are closer to the animals than to the plants, but traditionally fungi are often further treated in botany; until the late 20th century they were even counted among the plants.

Mushrooms combine typical features of animals as well as plants. Like plants, they are stuck, but unlike plants they do not photosynthesize; instead, they feed on organic substances from their environment. As a storage substance, they form the typical polysaccharide glycogen in animals (and no plant-typical starch). Although fungal cells usually have a typical cell wall for plant cells, but this is made up of the well-known in the animal kingdom chitin. Many fungi decompose dead organic material and are therefore ecologically of central importance in the nutrient cycle.

Symbiosis-living fungi can be found in most plants (eg trees and orchids) as well as in the lichens (a symbiosis of fungi with algae or cyanobacteria). Parasitic fungi are important pathogens in plants, animals and humans. Apart from delicacies such as truffles, mushrooms form the basis for daily foods such as bread and cheese, alcoholic beverages, and medicines such as antibiotics (penicillin). (Sb, pm)

Publication:
Hawksworth D., Lücking R. 2017. Fungal Diversity Revisited: 2.2 to 3.8 Million Species.
Microbiol Spectrum 5 (4): FUNK-0052-2016.