Ecocycles (Dec 2018)
How mushrooms tend to break through the evolutionary dead end
Abstract
Genes, genetics, genomics, and the roles of mushrooms and toadstools in the global carbon cycle (GCC) are reviewed here. The literature survey is a tribute to the contributions made by Hungary and Hungarian scientists to fungi and mushroom research. For this reason, the names of the fungi discussed are also given in Hungarian. Fungi – like wood eating insects – are the main decomposers (a type of consumers, syn.: heterotrophs) and consequently recycle the biomass produced by photosynthetic organisms (i.e., the producers, syn.: autotrophs). Photosynthesis is driven by the solar energy day by day (by photo-autotrophs) (i.e., primary producers of chlorophyllous plants), and primary production night by night is performed by chemo-autotroph prokaryotes. Only autotrophic organisms can produce organic materials in the Earth to supply food and feed the hetero-trophs (e.g., animals, including Human), and sapro-trophs (i.e., decomposers) including fungi and bacteria. The crucial excess oxygen from the oxygenic photosynthesis supports diverse life on Earth. Mushrooms were found to have 100-1000 times smaller genomes than plants or animals, however, enormous genome expansions e.g., of Armillarias (Eng./Hung.: honey mushrooms / tuskógombák) have indicated recently that fungi continue to expand their genome. Comparative genome analyses of Polyporales mushrooms have recently identified an ongoing transitioning from white-rot (WR) towards brown-rot (BR) life style with loss of genes encoding enzymes to decay cell wall components of plants (and woody plants, the trees) including cellulose, hemicellulases, lignin (the three together are also called lignocelluloses), and pectin. In the case of lignin, genes of ligninase enzymes, which are capable of digesting lignin only, developed only in wood-decay fungi which underscore their role in GCC. Symbiosis between fungi and green algae or cyanobacteria created a new phylum the Lichens (Mycophycophyta) in evolution. A tripartite symbiosis among achlorophyllous (i.e., parasitic) mycoheterotrophic plants ↔ mycorrhizal fungi ↔ and autotrophic green plants were re-discovered recently. Here we review the achievements of research of Di-caria true fungi (Eu-mycota) of both Asco-mycota (Eng./Hung.: Sac fungi / Tömlősgombák) and Basidio-mycota (Eng./Hung.: Club fungi / Bazidiumosgombák) with special emphasis on genes, genetics and genomic and evolutionary relationships. In brackets, the commercial mushroom names of English (Eng.) and Hungarian (Hung.) are given.
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