Editing Rust (fungus) (section)

==Infection process==
The spores of rust fungi may be [[Biological dispersal#Types of dispersal|dispersed by]] wind, water or [[insect vector]]s.<ref>Craigie, J.H. (1931). ''Phytopathology'', 21,1001</ref> When a spore encounters a susceptible plant, it can germinate and infect plant tissues. A rust spore typically germinates on a plant surface, growing a short hypha called a [[germ tube]]. This germ tube may locate a [[stoma]] by a touch responsive process known as [[thigmotropism]]. This involves orienting to ridges created by [[Epidermis (botany)|epidermal cells]] on the leaf surface, and growing directionally until it encounters a stoma.<ref>Dickinson, M. Molecular Plant Pathology. 2003.</ref>[[File:rust attacking stoma.jpg|thumb|Rust hypha attacking stoma (1600x magnification)]] Over the stoma, a [[hypha]]l tip produces an infection structure called an [[appressorium]]. From the underside of an appressorium, a slender hypha grows downward to infect plant cells.<ref>Deising, H. B., S. Werner, and M. Wernitz, The role of fungal appressoria in plant infection. Microbes Infect, 2000. 2(13): pp. 1631–41.</ref> It is thought that the whole process is mediated by stretch-sensitive [[calcium channel|calcium ion channels]] located in the tip of the hypha, which produce electric currents and alter [[gene expression]], inducing appressorium formation.<ref>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.</ref>

Once the fungus has invaded the plant, it grows into plant [[mesophyll]] cells, producing specialized hyphae known as [[haustorium|haustoria]]. The haustoria penetrate [[cell wall]]s but not [[cell membrane]]s: plant cell membranes invaginate around the main haustorial body forming a space known as the ''extra-haustorial matrix''. An [[iron]]- and [[phosphorus]]-rich neck band bridges the plant and fungal membranes in the space between the cells for water flow, known as the [[apoplast]], thus preventing the [[nutrient]]s reaching the plant's cells. The haustorium contains [[amino acid transporter|amino acid-]] and [[hexose transporter|hexose sugar-]] transporters and [[H+ ATPase|H<sup>+</sup>-ATPases]] which are used for [[active transport]] of nutrients from the plant, nourishing the fungus.<ref>Voegele, R. T., and K. Mendgen, Rust haustoria: nutrient uptake and beyond. New Phytologist, 2003. 159(1): pp. 93–100.</ref> The fungus continues growing, penetrating more and more plant cells, until [[sporulation|spore growth]] occurs. The process repeats every 10–14 days, producing numerous spores that can be spread to other parts of the same plant, or to new hosts.