Difference between revisions of "AY Honors/Fungi/Rust infection"

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noob noob dfo===Appresorium Formation===
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[[Image:Rustinfection.JPG|thumb|450px|Rust infection]]
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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.
  
The stomata is the site of [[appresorium]] formation, a structure that functions to both firmly anchor the fungus and aid in penetration.<ref>Deising, H.B., S. Werner, and M. Wernitz, The role of fungal appressoria in plant infection. Microbes Infect, 2000. 2(13): p. 1631-41.</ref> 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 dimefhghnsions of the stomatal lips of its [[Host (biology)|host]] species.  
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;Spore Attachment:
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When a rust 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 plant cell surface. Then unknown signals cause the production of a substance called ''adhesin''. This will stick the spore irreversibly to the plant surface. Once attached, the spore will germinate.
  
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 h[[cell mhembrane]] caused by changes in [[leaf]] [[topography]] into [[ion flux]]es that lead to changes in [[gene]] expression and appresorium formation.<ref>Zhou, X.L., et al., A mechanosensitive channel in whole cells and in membrane patches of the funhghdgus Uromyces. Science, 1991. 253(5026): p. 1415.</ref>. This theory is supported by experiments thdhat show that applying Ca<sup>2+</sup> externally to the germ tube causes [[differentiation]].
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;Germ Tube Elongation:
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Rust fungi penetrate the plant by using the natural pores on the underside of a leaf, but first the growing germ tube must locate it. The germ tube grows in a random manner until it reaches a ridge. At this point it will start to grow perpendicular to the ridge, greatly increasing its chances of locating a pore (called a ''stomata'').
  
From tfhe fhfhl]] cells.
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;Appresorium Formation:
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The stomata is the site of a structure called an ''appresorium'' that functions to both firmly anchor the fungus and aid in penetration. From the appresorium an infection peg grows down into the plant and between the leaf cells.
  
hfh===hfh
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;The Haustoria:
Rust fungi are [[bifhfotroph]]s, meaning thffhey gain their nutrients from living cells. This requires fffffffffffffffffa spffffffffalised fentenshonff of the ffungi infto a lihfving plfant 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 fhfghfghfgggggfd [[sugar]] transporters and H<sup>+</sup>-ATPases for the [[active transport]] of nutrients from the plant cell.<ref>Voegele, R.T. and K. Mendgen, Rustgfd haustoria: nutrient fg
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Rust fungi gain their nutrients from living cells. This requires a specialized penetration of the fungi into a living plant cell called a ''haustoria''. This develops from a haustorial mother cell. The plant cell membrane surrounds the main haustorial body. 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. The rust fungi will then continue to grow and invade the plant until it is ready to make new spores.
The rust hgImage:Rust fungus (Uredinales) Pengo.jpg|Rust fungus on a leaf, under low magnification.
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Image:t(fhdUredidgnales) pustules of urediniospores Pengo.jpg|Pustules of f:Rusthinfection.JPG| Cartoon representing the infection process of rust funghgi
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==See also==
 
*[[shoybehfdfgan rust]]
 
*[[fdghFungus Catastrophe]
 
* [http://fbotit.botany.fgwisc.edu/images/hfh/g[http://heliosg.bto.ed.ac.uk/bto/FungalBiology/hfgrust.htm#top ''Rust Fungi'' from Deacon, J: "Fungal Biology", Blackwell Publishing, 2005]
 
 
 
==References==
 
<references/>
 
 
 
[[Category:Basidiomycota]]
 
[[Category:Plant pathogens and diseases]]
 
 
 
[[da:Rustsvampe]]
 
[[de:Rostpilze]]
 
[[es:Urediniomycetes]]
 
[[eo:Rustofungoj]]
 
[[fr:Rouille (maladie)]]
 
[[nl:Roesten]]
 

Latest revision as of 23:25, 14 July 2022

Rust infection

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.

Spore Attachment

When a rust 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 plant cell surface. Then unknown signals cause the production of a substance called adhesin. This will stick the spore irreversibly to the plant surface. Once attached, the spore will germinate.

Germ Tube Elongation

Rust fungi penetrate the plant by using the natural pores on the underside of a leaf, but first the growing germ tube must locate it. The germ tube grows in a random manner until it reaches a ridge. At this point it will start to grow perpendicular to the ridge, greatly increasing its chances of locating a pore (called a stomata).

Appresorium Formation

The stomata is the site of a structure called an appresorium that functions to both firmly anchor the fungus and aid in penetration. From the appresorium an infection peg grows down into the plant and between the leaf cells.

The Haustoria

Rust fungi gain their nutrients from living cells. This requires a specialized penetration of the fungi into a living plant cell called a haustoria. This develops from a haustorial mother cell. The plant cell membrane surrounds the main haustorial body. 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. The rust fungi will then continue to grow and invade the plant until it is ready to make new spores.