Telium, plural telia, are structures produced by

rust fungi Rusts are plant diseases caused by pathogenic fungi of the order Pucciniales (previously known as Uredinales). An estimated 168 rust genera and approximately 7,000 species, more than half of which belong to the genus ''Puccinia'', are currently a ...

as part of the

reproductive cycle In biology, a biological life cycle (or just life cycle or lifecycle when the biological context is clear) is a series of changes in form that an organism undergoes, returning to the starting state. "The concept is closely related to those of the ...

. They are typically yellow or orange drying to brown or black and are exclusively a mechanism for the release of

teliospore Teliospore (sometimes called teleutospore) is the thick-walled resting spore of some fungi ( rusts and smuts), from which the basidium arises. Development They develop in '' telia'' (sing. ''telium'' or ''teliosorus''). The telial host is the p ...

s which are released by wind or water to infect the alternate

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman * Michel Host ...

in the rust life-cycle. The telial stage provides an overwintering strategy in the life cycle of a

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has c ...

heteroecious A heteroecious parasite is one that requires at least two hosts. The ''primary host'' is the host in which the parasite spends its adult life; the other is the ''secondary host''. Both hosts are required for the parasite to complete its life cycle ...

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

by producing teliospores; this occurs on cedar trees. A primary aecial stage is spent parasitizing a separate host plant which is a precursor in the life cycle of heteroecious fungi. Teliospores are released from the telia in the spring. The

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

s can spread many kilometers through the air, however most are spread near the host plant.

Host plants

There are a number of plants that can be infected by the telial stage. Therefore, the telial stage is considered a

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

to those plants. A few specific plant pathogenic species are listed here with their

hosts A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places *Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman *Michel Host ( ...

. # ''

Puccinia graminis Stem rust, also known as cereal rust, black rust, red rust or red dust, is caused by the fungus ''Puccinia graminis'', which causes significant disease in cereal crops. Crop species that are affected by the disease include bread wheat, durum whe ...

'' or known commonly as black stem rust. It infects many different cereal crops. # ''

Gymnosporangium juniperi-virginianae ''Gymnosporangium juniperi-virginianae'' is a plant pathogen that causes cedar-apple rust. In virtually any location where apples or crabapples (''Malus'') and Eastern red cedar (''Juniperus virginiana'') coexist, cedar apple rust can be a destr ...

''. It infects the eastern red cedar. This is shown to the right. # '' Gymnosporangium sabinae''. It infects pear trees. File:Stem rust close up.jpg, ''

'' on wheat. File:Gymnosporangium sabinae fg05.JPG, '' Gymnosporangium sabinae'' on a pear tree leaf.

Spore stages

The life cycle of rust fungi can have up to five different spore stages and can get quite complex.Schumann, G.L. et al. 2010. Essential Plant Pathology. American Phytopathological Society. Second Edition. St. Paul. pp. 43–44 These stages are: * Stage 0:

Pycniospore Pycniospores are a type of spore in fungi. They are produced in special cup-like structures called pycnia or pynidia. Almost all fungi reproduce asexually with the production of spores. Spores may be colorless, green, yellow, orange, red, brown or ...

s * Stage I:

Aeciospore Aeciospores are one of several different types of spores formed by Rusts. They each have two nuclei and are typically seen in chain-like formations in the aecium An aecium (plural aecia) is a specialised reproductive structure found in some pl ...

s * Stage II:

Urediniospore Urediniospores (or uredospores) are thin-walled spores produced by the uredium, a stage in the life-cycle of rusts. Development ''Urediniospores'' develop in the uredium, generally on a leaf's under surface. Morphology *Urediniospores usually hav ...

s * Stage III:

Teliospore Teliospore (sometimes called teleutospore) is the thick-walled resting spore of some fungi ( rusts and smuts), from which the basidium arises. Development They develop in '' telia'' (sing. ''telium'' or ''teliosorus''). The telial host is the p ...

s * Stage IV:

Basidiospore A basidiospore is a reproductive spore produced by Basidiomycete fungi, a grouping that includes mushrooms, shelf fungi, rusts, and smuts. Basidiospores typically each contain one haploid nucleus that is the product of meiosis, and they are pro ...

s File:Puccina graminis lifecycle.gif, Life Cycle of ''Puccina graminis''

References

Fungal morphology and anatomy Reproduction {{plant-disease-stub