How mushrooms break through the evolutionary dead end?

Genetics and the roles of mushrooms in the global carbon cycle

Abstract

Genes, genetics, genomics, and the roles of mushrooms and toadstools in the global carbon cycle are reviewed here.

Fungi – similar to wood eating insects – are the main decomposers (a type of consumers or heterotrophs), and consequently recyclers of biomass produced by photosynthetic organisms (i.e., the producers or autotrophs).

Photosynthesis is driven by the solar energy day by day (of Photoautotrophs) (i.e., primary producers), and night by night (of Chemoautotroph bacteria) for billions of years. Only photosynthetic organisms can produce organic materials in the Earth to supply food and feed to the Heterotrophs (animals, including Human), and Saprotrophs (i.e., decomposers) including fungi and bacteria. The crucial excess oxygen the photosynthesis produces oxygenates and maintains the life in the Earth.

Mushrooms were found to have 100-1000 times smaller genomes than plants or animals, however, enormous genome expansions of Armillarias (Eng./Hung.: honey mushrooms / tuskógombák) have indicated recently that fungi tend to break out from their closed evolutionary dead end.

Comparative genome analyses of Polyporales mushrooms have recently identified an ongoing transitioning evolutionary stage from white-rot (WR) towards brown-rot (BR) life style with loss of genes encoding enzymes to decay cell wall components of plants and trees including cellulose, hemicellulases, lignin (the three together also called lignocelluloses), and pectin. In the case of lignin, ligninase enzyme genes were evolved only in fungi to decay lignin of plants.

A tripartite symbiosis among achlorophyllous (i.e., parasitic) mycoheterotrophic plants ? mycorrhizal fungi ? and autotrophic green plants were re-discovered recently.

Here we review all of these new achievements in the research of Dicaria true fungi (Eumycota) of both Ascomycota (Eng./Hung.: Sac fungi / Töml?sgombák) and Basidiomycota (Eng./Hung.: Club fungi / Bazidiumosgombák) with special emphasis on genes, genetics, genomics and evolutionary relationships.