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Encyclopedia > Rust (fungus)
Rusts
Puccinia recondita f.sp. tritici on wheat leaf
Puccinia recondita f.sp. tritici on wheat leaf
Scientific classification
Kingdom: Fungi
Division: Basidiomycota
Class: Urediniomycetes
Order: Uredinales
Families

Pucciniaceae
Melampsoraceae
Coleosporiaceae
Cronartiaceae
Phragmidiaceae
Pucciniastraceae Image File history File links Download high resolution version (2270x805, 370 KB) Picture taken by myself: (nl: Bruine roest op tarwe) Puccinia recondita f. ... For other uses, see Scientific classification (disambiguation). ... Subkingdom/Phyla Chytridiomycota Blastocladiomycota Neocallimastigomycota Glomeromycota Zygomycota Dikarya (inc. ... Subphyla/Classes Pucciniomycotina Ustilaginomycotina Agaricomycotina Incertae sedis (no phylum) Wallemiomycetes Entorrhizomycetes Basidiomycota is one of two large phyla, that together with the Ascomycota, comprise the subkingdom Dikarya, which were in general what were called the Higher Fungi within the Kingdom Fungi. ... Urediniomycetes is a diverse class of fungi that includes several important plant pathogens causing forms of fungal rust. ... The Pucciniaceae are a family of rust fungi that cause plant diseases. ... Genera Cronartium Endocronartium Peridermium Cronartiaceae is a family of rust fungi in the order Uredinales. ...

Rusts are fungi of the order Uredinales. Many of these species are plant parasites. Some are superficially similar to the smuts, although their relation to each other is not clear. The taxonomy of Urediniomycota, as a whole, is in a state of flux. Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ... A parasite is an organism that lives in or on the living tissue of a host organism at the expense of it. ... The smuts are fungi, mostly Ustilaginomycetes (of the class Teliomycetae, subphylum Basidiomycota), that cause plant disease. ...


Many of the rusts have two or more hosts (heteroecious) and up to five spore stages. However they most commonly reproduce via asexual spore production. Their spores are airborne and can travel great distances. They mostly cause foliar infections. A heteroecious parasite is one that requires at least two hosts. ... This article is about human asexuality; asexual reproduction is a separate topic. ... This article or section is in need of attention from an expert on the subject. ...


The group received its common name from the fact that some species have a reddish spore stage, which resembles the corrosion process known as rust. This article or section is in need of attention from an expert on the subject. ... For other uses, see Rust (disambiguation). ...

Contents

Infection Process

Rust occurs on many species of plant, but in most cases any one species of rust can only infect one species of plant. The following describes the infection process of asexual spores. A picture summarizing the process can be found in the gallery below.


Spore Attachment

When a rust conidia spore lands on a plant surface it needs to attach to it, or it would simply be washed off. First, weak, hydrophobic interactions are formed between the spore and the cutin of the plant cell surface. Then unknown signals cause the production of hydrophobic mucilaginous macromolecules called adhesins. These will stick the spore irreversibly to the plant surface.[1] Once attached, the spore will germinate. Conidia are asexual spores of fungus. ... In chemistry, hydrophobic or lipophilic species, or hydrophobes, tend to be electrically neutral and nonpolar, and thus prefer other neutral and nonpolar solvents or molecular environments. ... Cutin is a waxy substance which is a component of cuticle at the surface of leaves in plants. ...


Germ Tube Elongation

Rust fungi penetrate the plant by using the natural opening of the stomata, but first the growing germ tube must locate it. Rust fungi have evolved to more efficiently locate stomata by the use of thigmotropism. The germ tube grows in a random manner until it reaches a ridge between epidermal cells. At this point it will start to grow perpendicular to the ridge, greatly increasing its chances of locating a stomata.[2] This is not about surgically created bowel openings; see stoma (medicine) In botany, a stoma (also stomate; plural stomata) is a tiny opening or pore, found mostly on the undersurface of a plant leaf, and used for gas exchange. ... A germ tube is an outgrowth produced by certain species of spore-releasing fungi (sporangia) during germination. ... Thigmotropism is a tropism in which an organism moves or grows in response to touch or contact stimuli. ... Look up Epidermis in Wiktionary, the free dictionary. ... Fig. ...


Appresorium Formation

The stomata is the site of appresorium formation, a structure that functions to both firmly anchor the fungus and aid in penetration.[3] In the rust fungi appresorial formation is controlled by a process of thigmodifferentiation. Appresoria are formed when the germ tube detects ridges that match the dimensions of the stomatal lips of its host species. Appresoria, the plural of appresorium, are the tips of infectious hyphae, often from a germinating spore, that make contact with their host cell wall and that flatten out into disc, fan or lobed shapes tightly affixed or appressed on the host cell wall. ...


It has been proposed that this process is mediated by a mechanosensitive calcium ion channel that is located at the germ tube tip. This ion channel would transduce the stretching of the cell membrane caused by changes in leaf topography into ion fluxes that lead to changes in gene expression and appresorium formation.[4]. This theory is supported by experiments that show that applying Ca2+ externally to the germ tube causes differentiation. For other uses, see Calcium (disambiguation). ... This article is about the electrically charged particle. ... Look up cell membrane in Wiktionary, the free dictionary. ... Look up foliage in Wiktionary, the free dictionary. ... For discussion of land surfaces themselves, see Terrain. ... For other uses, see Gene (disambiguation). ... Differentiation can mean the following: In biology: cellular differentiation; evolutionary differentiation; In mathematics: see: derivative In cosmogony: planetary differentiation Differentiation (geology); Differentiation (logic); Differentiation (marketing). ...


From the appresoria an infection peg growns down into the plant and between the mesophyll cells. This article is about the leaf, a plant organ. ...


The Haustoria

Rust fungi are biotrophs, meaning they gain their nutrients from living cells. This requires a specialised entension of the fungi into a living plant cell called a haustoria. This develops from a haustorial mother cell. The plant cell membrane invaginates around the main haustorial body and the space between the two membranes becomes known as the extra-haustorial matrix. An iron and phosphorus rich neck band bridges the plant and fungal membranes and acts as a seal preventing the escape of nutrients into the plant apoplast. The haustoria contains amino acid and hexose sugar transporters and H+-ATPases for the active transport of nutrients from the plant cell.[5] Mites parasitising a harvestman Parasitism is one version of symbiosis (living together), a phenomenon in which two organisms which are phylogenetically unrelated co-exist over a prolonged period of time, usually the lifetime of one of the individuals. ... Haustorium, plural Haustoria, is the hyphal tip of a parasitic fungus that penetrates the hosts tissue, but stays outside the host cell membrane. ... For other uses, see Iron (disambiguation). ... General Name, symbol, number phosphorus, P, 15 Chemical series nonmetals Group, period, block 15, 3, p Appearance waxy white/ red/ black/ colorless Standard atomic weight 30. ... A nutrient is either a chemical element or compound used in an organisms metabolism or physiology. ... Within a plant, the apoplast is the free diffusional space outside the plasma membrane. ... This article is about the class of chemicals. ... A hexose is a monosaccharide with six carbon atoms having the chemical formula C6H12O6. ... This article is about sugar as food and as an important and widely traded commodity. ... Sodium-Potassium pump, an example of Primary active transport secondary active transport Active transport (sometimes called active uptake) is the mediated transport of biochemicals, and other atomic/molecular substances, across membranes. ...


The rust fungi will then continue to grow and invade the plant until it is ready for sporulation. It has been suggested that this article or section be merged into Spore. ...


Gallery

See also

Species Phakopsora meibromiae Phakopsora pachyrizi Soybean rust, sometimes also called Asian soybean rust, is a disease that affects soybeans and other legumes. ... It has been suggested that this article or section be merged with Brown rust. ... In Roman mythology, Robigus (wheat rust or mildew) was a fertility god who protected crops against diseases. ... Binomial name Senecio vulgaris Groundsel (Senecio vulgaris) is a cosmopolitan (world-wide) annual weed of cultivation in the family Asteraceae. ...

External links

References

  1. ^ Osherov, N. and G.S. May, The molecular mechanisms of conidial germination. FEMS Microbiol. Lett, 2001. 199(2): p. 153–160.
  2. ^ Dickinson, M. Molecular Plant Pathology. 2003.
  3. ^ Deising, H.B., S. Werner, and M. Wernitz, The role of fungal appressoria in plant infection. Microbes Infect, 2000. 2(13): p. 1631-41.
  4. ^ Zhou, X.L., et al., A mechanosensitive channel in whole cells and in membrane patches of the fungus Uromyces. Science, 1991. 253(5026): p. 1415.
  5. ^ Voegele, R.T. and K. Mendgen, Rust haustoria: nutrient uptake and beyond. New Phytologist, 2003. 159(1): p. 93-100.

  Results from FactBites:
 
Rust - Wikipedia, the free encyclopedia (553 words)
Rust is the substance formed when iron compounds corrode in the presence of water and oxygen.
Rusting is a common term for corrosion, and usually corrosion of steel.
The process of rusting can be summarized as three basic stages: The formation of iron(II) ions from the metal; the formation of hydroxide ions; and their reaction together, with the addition of oxygen, to create rust.
  More results at FactBites »

 
 

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