30. Mushroom Life Cycle Nuclear fusion in basidium Meiosis Hyphal fusion of haploid mycelia haploid mycelium young basidia - the only diploid cells mycelium and fruiting body are dikaryotic N 2N N+N
Most enzyme release (and absorption) at tips Proteins and other materials synthesized by the entire mycelium are channeled by cytoplasmic streaming to the tips of the extending hyphae.
Chitin is the same material used by Arthropods (Insects, crabs, etc.) in their exoskeletonsa Nuclei of fungi are hard to see without stains
Half of the mushroom-forming fungi (basidiomycota) form mycorrhizas with trees Some people think that the spongy tissue in roots evolved as a place where fungi could invade to form early links with plants that helped them survive the harsh life on early earth
4 of the regions where mycorrhizas are found are circled. These are “ecto” because the hyphae remain outside the root cells (though they extend inside the root)
Thallus is a plant-like body that doesn’t have roots, stems or leaves Thallus doesn’t look like either partner Dual nature of thalli was not fully understood until early 1900’s Fungus gives the name to the lichen (by agreement) Fungus usually, but not always, an Ascomycote (in 8+ independent orders) Algae green. If bluegreen bacteria present, lichens fix nitrogen (turn atmospheric nitrogen into amino acid nitrogen in proteins)
The nature of lichen symbiosis is may also be described as mutual exploitation instead of mutual benefit. Lichens live in environments where neither fungi nor algae could live alone. While the fungi do not not grow alone in the wild, some (but not all) lichen algae occur as free-living organisms. If cultured separately, the fungi do not produce lichen compounds and the algae do not “leak” carbohydrate from their cells. In some lichens, the fungus invades algal cells with haustoria and kills some of them, but not as fast as the algae replenish its numbers by reproduction. Lobaria oregana prefers old-growth conifer canopies in forests with clean air.
Fungi reproduce by releasing spores that are produced either sexually or asexually. The output of spores from one reproductive structure is enormous, with the number reaching into the trillions. Dispersed widely by wind or water, spores germinate to produce mycelia if they land in a moist place where there is food.
Fungal mycelia can be huge, but they usually escape notice because they are subterranean. One giant individual of Armillaria ostoyae in Oregon is 3.4 miles in diameter and covers 2,200 acres of forest, It is at least 2,400 years old, and weighs hundreds of tons. (Actually noone has seen this of this extent – but cultures have been taken from soil over that area and all isolates have been found to be the same individual) Ten cubic centimeters of rich organic soil may have fungal hyphae with a surface area of over 300 cm 2
Molecular studies indicate that animals, not plants, are the closest relatives of fungi. Both Animals and Fungi are related most closely to a group of Protists known as the choanoflagellates (collar flagellates) Kingdom began in ocean during Precambrian (Late Proterozoic era) More than 100,000 species of fungi are known and mycologists estimate that there are actually about 1.5 million species worldwide.
The phyla of fungi are determined by 1. motility of spores 2. nature of sexual stage Fungi moved onto land with the plants in the Early Paleozoic Much of the evolution of fungi was in conjunction with the evolution of plants and plant parts For example, when roots evolved, fungi were there and helped (mycorrhizas) When wood evolved, fungi evolved to take advantage of it Other evolutionary changes related to animals
Classified in CMR as true fungi (because of their molecular relationships) Remainder of the phyla are almost exclusively terrestrial (a few molds on wet plant material)
Most of the 600 zygomycote, or zygote fungi , are terrestrial, living in soil or on decaying plant and animal material. Asexual reproduction in sporangia One zygomycote group form mycorrhizas , mutualistic associations with the roots of plants.
Mycologists have described over 60,000 species of ascomycetes, or sac fungi . Ascomycota tend to grow from spore to spore in one year and relate well to living plant tissues There is diverse form in the growth and fruiting structures – yeasts to morels, many intermediate (and small) Asexual reproduction by conidia (externally produced, not in sporangia) Half of the Ascomycota form lichens (evolved 8 or more times in different orders) but not all lichens are Ascomycotes
This begins the first of several photographic reviews of fungal diversity. Enjoy the pictures and try and get a feeling of some of the different forms these fungi take and their roles in the environment.
Asexual spores conidia Ecologically important on wood as decomposers and parasites Half the mushrooms form mycorrhizas
Bread and wine yeast, the budding yeast, Saccharomyces Easily cultured. For a time, this was the most important organism for studying the molecular genetics of eukaryotes Thus, Saccharomyces is arguably the most important organism known to humans Candida causes diseases of humans, usually experiencing chemical imbalance or immune problems
A mold is a rapidly growing, asexually reproducing fungus. The mycelia of these fungi grow as saprobes or parasites on a variety of substrates. Also used in foods (Blue cheese, Tempeh) and in industrial production of drugs Early in life, a mold, a term that applies properly only to the asexual stage, produces asexual spores. Later, the same fungus may reproduce sexually, producing zygosporangia, ascocarps, or basidiocarps Some molds go through a “fake sex” process
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