Kingdom Fungi is comprised of organisms such as mushrooms, molds, and yeasts, which are eukaryotic heterotrophs that digest food outside of their bodies. Fungi contain no vascular tissue. Most fungi are multicellular, but some, the yeasts, are simple unicellular organisms. Fungi are present all over the world, in marine as well as terrestrial environments. Many fungi have symbiotic relationships with plants, and protists.

Most fungi are decomposers, breaking organic tissues down into detritus and returning nutrients to the ecosystem. Fungi secrete enzymes which digest the food source outside of their body, and then they absorb the nutrients through their hyphae. Fungi are also extremely adaptable, and can break down many substances, including some toxic pollutants. Sometimes the fungus doesn't wait for the organism to die, in which case the fungus is called a parasite. Another thing that sets fungi apart from plants and other organisms with cell walls, is the presence of chitin. Chitin is a polysaccharide that is beneficial as a structural strengthener in the fungi organism.

• Some fungi are parasitic, and cause devastating plant, and sometimes animal infections.

• Serious agricultural pests, parasitic fungi such as the rusts and the smuts can ruin entire crops, especially affecting cereals such as wheat and corn.

• Yeasts are necessary for bread baking, and we eat many fungi, such as the mushrooms, and moldy cheese. • Many medical applications of fungi have recently been discovered, especially antibiotics produced by fungi. The first among these is penicillin, possibly the most important non-genetic medical breakthrough of the century.

Hyphae

Mycelium

Sporangia

Cytoplasmic movement between cells within the hyphae allows for transport of nutrients within the mold organism

A mass of hyphae

The fruiting body, or place where spores are found (reproductive function)

Stipe

Pileus

Budding Yeast Cells

AsexualMost fungi can reproduce asexually by what is called “budding”. “Fragmentation” is a form of asexual reproduction that occurs when a chunk of fungi breaks off and produces another fungal body.

The most common way for fungi to reproduce is called “sporulation”. The fruiting body of the fungi (sporangia) produces spores which under favorable conditions will germinate and initiate the growth of a new organism. Some fungi form conidia at the tips of specialized hyphae, not enclosed within a sac (like sporangia). These are called conidiophores.

Sexual reproduction can also occur in fungi. This occurs when hyphae of opposite mating types grow together and fuse.

•The haploid hyphal nuclei grow and undergo subsequent division, but they remain in pairs, one nucleus from each of the two parental hyphae. Such hyphae are called dikaryotic.

•Nuclear fusion occurs in time, forming diploid zygotes. Karyogamy is the fusing of two haploid nuclei, to form a single diploid nucleus.

Plasmogamy

•The zygote then immediately undergoes meiosis to form haploid spores that are distributed in the same manner as the vegetative spores.

The dominant form for fungal organisms is haploid.

Club Fungi

This is what you should think of when you see the typical supermarket mushroom.

Basidiomycota. The phylum is distinguished by its reproductive structure, the club-like basidium, which contains the products of sexual reproduction called basidiospores.

Basidiomycota include mushrooms, puffballs, and bracket fungi. Some basidiomycetes, the rusts and smuts, are serious crop pests, while others can be used for food or medical products. Some members of this phyla can also be deadly because of their poison.

Wheat seed with smut fungi

Ascomycota. Most times (98%) the fungal partner in lichen (symbiosis with an algae) is an ascomycota.

Sac FungiProduce their spores in special pods or sac-like structures called asci

Morel and Truffle mushrooms

Many serious plant pathogens are in this phylum, including Dutch Elm Disease and apple scab. The group also includes beneficial yeasts (vital to baking and brewing industries), powdery mildews, and highly prized edible fungi, including the morels and truffles, and Penicillium used to flavor blue cheese.

Zygomycota. These are the “algae-like” fungi.

Lichensa symbiotic union between fungus and algae (usually a chlorophyta or cyanobacteria)

Some examples are common bread molds and parasites of protists, nematodes, insects, and small animals

The Zygomycota has the simplest of life cycles. Asexual reproduction consists of the hyphae producing an erect thread-like structure with a bulb or sporangium. The sporangium produces haploid spores that are shed, germinate, and produce more fungal hyphae. The classic example of the Zygomycota is Rhizopus, black bread mold.

Imperfect FungiAround 25,000 additional fungus species are grouped in this phylum.

Members include Trichophyton (Athlete's foot), Penicillium notatum (Penicillin), and Candida albicans ("Yeast" infections).

Deuteromycota. These fungi are often termed “fungi imperfecti” because sexual reproduction has never been observed in them. They lack the structures for sexual reproduction, and produce their spores asexually.

In addition, the Mycorrhizae are mutualistic associations between fungi and roots of plants. The plant provides sugars to the fungi, while the fungi increases the ability of the roots to absorb water and minerals…especially phosphorus.

Root ball of bonsai plant