The Full Wiki

spore: Wikis


Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.

Encyclopedia

For the game, see Spore (2008 video game).

In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoans.[1] A chief difference between spores and seeds as dispersal units is that spores have very little stored food resources compared with seeds.

Spores are usually haploid and unicellular and are produced by meiosis in the sporangium by the sporophyte. Once conditions are favorable, the spore can develop into a new organism using mitotic division, producing a multicellular gametophyte, which eventually goes on to produce gametes.

Two gametes fuse to create a new sporophyte. This cycle is known as alternation of generations, but a better term is "biological life cycle", as there may be more than one phase and so it cannot be a direct alternation. Haploid spores produced by mitosis (known as mitospores) are used by many fungi for asexual reproduction.

Many ferns, especially those adapted to dry conditions, produce diploid spores. This form of asexual reproduction is called apogamy. It is a form of apomixis.

Spores are the units of asexual reproduction, because a single spore develops into a new organism. By contrast, gametes are the units of sexual reproduction, as two gametes need to fuse to create a new organism.

Contents

Definition

The term spore derives from the ancient Greek word σπορα ("spora"), meaning a seed.

In common parlance, the difference between a "spore" and a "gamete" (both together called gonites) is that a spore will germinate and develop into a sporeling, while a gamete needs to combine with another gamete before developing further. However, the terms are somewhat interchangeable when referring to gametes.

A chief difference between spores and seeds as dispersal units is that spores have little food storage compared with seeds, and thus require more favorable conditions in order to successfully germinate. (This is not without its exceptions, however: many orchid seeds, although multicellular, are microscopic and lack endosperm, and spores of some fungi in the Glomeromycota commonly exceed 300 µm in diameter.)[2] Seeds, therefore, are more resistant to harsh conditions and require less energy to start mitosis. Spores are produced in large numbers to increase the chance of a spore surviving in a number of notable examples.

Classification

Spores can be classified in several ways such as:

By spore-producing structure

of Morchella elata, containing ascospores.]]

s, microspores, and in some cases megaspores, are formed from all four products of meiosis.]] s and heterosporous ferns, only a single product of meiosis will become a megaspore (macrospore), with the rest degenerating.]] In fungi and fungus-like organisms, spores are often classified by the structure in which meiosis and spore production occurs. Since fungi are often classified according to their spore-producing structures, these spores are often characteristic of a particular taxon of the fungi.

By function

  • Chlamydospores: thick-walled resting spores of fungi produced to survive unfavorable conditions.
  • Parasitic fungal spores may be classified into internal spores, which germinate within the host, and external spores, also called environmental spores, released by the host to infest other hosts.[3]

By origin during life cycle

By motility

Spores can be differentiated by whether they can move or not.

  • Zoospores: mobile spores that move by means of one or more flagella, and can be found in some algae and fungi.
  • Aplanospores: immobile spores that may nevertheless potentially grow flagella.
  • Autospores: immobile spores that cannot develop flagella.
  • Ballistospores: spores that are actively discharged from the body of the fungal fruiting body. Most basidiospores are also ballistospores, and another notable example is spores of Pilobolus.
  • Statismospores: spores that are not actively discharged from the fungal fruiting body. Examples are puffballs.

Anatomy

Under high magnification, spores can be categorized as either monolete spores or trilete spores. In monolete spores, there is a single line on the spore indicating the axis on which the mother spore was split into four along a vertical axis. In trilete spores, all four spores share a common origin and are in contact with each other, so when they separate, each spore shows three lines radiating from a center pole.

Vascular plant spores are always haploid. Vascular plants are either homosporous (or isosporous) or heterosporous. Plants that are homosporous produce spores of the same size and type. Heterosporous plants, such as spikemosses, quillworts, and some aquatic ferns produce spores of two different sizes: the larger spore in effect functioning as a "female" spore and the smaller functioning as a "male".

Trilete spores

Trilete spores, formed by the dissociation of a spore tetrad, are taken as the earliest evidence of life on land,[4] dating to the mid-Ordovician (early Llanvirn, ~470 million years ago).[5]

Dispersal

File:Fungus spore ejection.ogg
Spores being ejected by fungi.

In fungi, both asexual and sexual spores or sporangiospores of many fungal species are actively dispersed by forcible ejection from their reproductive structures. This ejection ensures exit of the spores from the reproductive structures as well as travelling through the air over long distances. Many fungi thereby possess specialized mechanical and physiological mechanisms as well as spore-surface structures, such as hydrophobins, for spore ejection. These mechanisms include, for example, forcible discharge of ascospores enabled by the structure of the ascus and accumulation of osmolytes in the fluids of the ascus that lead to explosive discharge of the ascospores into the air.[6] The forcible discharge of single spores termed ballistospores involves formation of a small drop of water (Buller's drop), which upon contact with the spore leads to its projectile release with an initial acceleration of more than 10,000 g.[7] Other fungi rely on alternative mechanisms for spore release, such as external mechanical forces, exemplified by puffballs. Attracting insects, such as flies, to fruiting structures, by virtue of their having lively colours and a putrid odour, for dispersal of fungal spores is yet another strategy, most prominently used by the stinkhorns.

In the case of spore-shedding vascular plants such as ferns, wind distribution of very light spores provides great capacity for dispersal. Also, spores are less subject to animal predation than seeds because they contain almost no food reserve; however they are more subject to fungal and bacterial predation. Their chief advantage is that, of all forms of progeny, spores require the least energy and materials to produce.

In the spikemoss Selaginella lepidophylla, dispersal is achieved in part by an unusual type of diaspore, a tumbleweed.[citation needed]

See also

References

  1. ^ Spore FAQ - Aerobiology Research Laboratory
  2. ^ INVAM
  3. ^ [1].
  4. ^ Gray, J. (1985). "The Microfossil Record of Early Land Plants: Advances in Understanding of Early Terrestrialization, 1970-1984". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences (1934-1990) 309 (1138): 167–195. doi:10.1098/rstb.1985.0077. http://links.jstor.org/sici?sici=0080-4622(19850402)309%3A1138%3C167%3ATMROEL%3E2.0.CO%3B2-E. Retrieved on 2008-04-26. 
  5. ^ Wellman, C.H., Gray, J. (2000). "The microfossil record of early land plants". Philosophical Transactions: Biological Sciences 355 (1398): 717–732. doi:10.1098/rstb.2000.0612. http://www.journals.royalsoc.ac.uk/index/2NWB35JF2C34PJHG.pdf. Retrieved on 2008-02-13. 
  6. ^ Trail F. (2007). "Fungal cannons: explosive spore discharge in the Ascomycota". FEMS Microbiology Letterrs 276: 12–8. doi:10.1111/j.1574-6968.2007.00900.x. PMID 17784861. 
  7. ^ Pringle A, Patek SN, Fischer M, Stolze J, Money NP. (2005). "The captured launch of a ballistospore". Mycologia 97: 866–71. doi:10.3852/mycologia.97.4.866. PMID 16457355. 

Gallery


Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

Contents

English

Pronunciation

Etymology

From Modern Latin spora, from Ancient Greek σπορά (spora), seed, a sowing), related to σπόρος (sporos), sowing) and σπείρω (speirō), to sow), from PIE *sper- "to strew"

Noun

Singular
spore

Plural
spores

spore (plural spores)

Wikipedia-logo.png
Wikipedia has an article on:

Wikipedia

  1. A reproductive particle, usually a single cell, released by a fungus, alga, or plant that may germinate into another.
  2. A thick resistant particle produced by a bacterium or protist to survive in harsh or unfavorable conditions.

Translations

Related terms

See also

Verb

Infinitive
to spore

Third person singular
spores

Simple past
spored

Past participle
spored

Present participle
sporing

to spore (third-person singular simple present spores, present participle sporing, simple past and past participle spored)

  1. To produce spores.

Anagrams


Italian

Noun

spore f.

  1. Plural form of spora.

Simple English

]] A spore is the way fungi and some non-flowering plants, such as ferns and mosses reproduce (make new fungi or plants), the same way seeds of other plants do.[1]

Fungi (for example, mushrooms) produce spores, which may be asexual or sexual. The asexual spores have inside them the genetic material to make a whole new organism identical to its parent.


Conidia are asexual,[2] non-motile spores of a fungus; they are also called mitospores due to the way they are generated through the cellular process of mitosis. They are haploid cells genetically identical to the haploid parent, can develop into a new organism if conditions are favorable, and serve in dispersal.

Asexual reproduction in Ascomycetes (the Phylum Ascomycota) is by the formation of conidia, which are bourne on specialized stalks called conidiophores. The morphology of these specialized conidiophores is often distinctive of a specific species and can therefore be used in identification of the species.

Bacterial spores

Bacterial spores are extremely resistant. Spores of tetanus and anthrax, for example, can survive in the soil for many years. The origin of these spores was discovered in the 19th century, when a biologist noticed, under the microscope, a small, round, bright body inside bacterial cells. This survived even when the bacteria were boiled for five minutes. This killed the bacteria, but not the spores. They germinated when conditions were right.[3]p186

References

  1. Spore FAQ - Aerobiology Research Laboratory
  2. Osherov N, May GS (May 2001). "The molecular mechanisms of conidial germination". FEMS Microbiol. Lett. 199 (2): 153–60. PMID 11377860. http://linkinghub.elsevier.com/retrieve/pii/S0378109701001781. 
  3. Kornberg, Arthur 1989. For the love of enzymes: the odyssey of a biochemist. Harvard.







Got something to say? Make a comment.
Your name
Your email address
Message