Editing Rust (fungus) (section)

{{Short description|Order of fungi}}
{{Automatic taxobox 
| name = Rusts
| image = Bruine roest op tarwe (Puccinia recondita f.sp. tritici on Triticum aestivum).jpg
| image_caption = Example of wheat leaf from a disease differential of [[Puccinia recondita f.sp. tritici|''Puccinia recondita'' f.sp. ''tritici'']]
| taxon = Pucciniales
| authority =
| subdivision_ranks = Families
| subdivision =
*[[Araucariomycetaceae]]<ref name = A&M2021/>
*([[Chaconiaceae]])
*[[Coleosporiaceae]]
*([[Cronartiaceae]])
*[[Crossopsoraceae]]<ref name = A&M2021/>
*[[Gymnosporangiaceae]]
*[[Melampsoraceae]]
*[[Milesinaceae]]<ref name = A&M2021/>
*[[Ochropsoraceae]]<ref name = A&M2021/>
*[[Phakopsoraceae]]
*[[Phragmidiaceae]]
*[[Pileolariaceae]]
*[[Pucciniaceae]]
*[[Pucciniosiraceae]]
*[[Pucciniastraceae]]
*[[Raveneliaceae]]
*[[Rogerpetersoniaceae]]<ref name = A&M2021/>
*[[Skierkaceae]]<ref>{{cite web |title=Species Fungorum - Search Page |url=http://www.speciesfungorum.org/Names/Names.asp?strGenus=Skierka |website=www.speciesfungorum.org |access-date=27 October 2022 |archive-date=9 October 2023 |archive-url=https://web.archive.org/web/20231009003036/https://www.speciesfungorum.org/Names/Names.asp?strGenus=Skierka |url-status=live }}</ref>
*[[Sphaerophragmiaceae]]
*[[Tranzscheliaceae]]<ref name = A&M2021/>
*([[Uropyxidaceae]])
*[[Zaghouaniaceae]] (incorporating [[Mikronegeriaceae]])<ref name = A&M2021>{{cite journal | pmc=8165960 | date=2021 | last1=Aime | first1=M. C. | last2=McTaggart | first2=A. R. | title=A higher-rank classification for rust fungi, with notes on genera | journal=Fungal Systematics and Evolution | volume=7 | pages=21–47 | doi=10.3114/fuse.2021.07.02 | pmid=34124616 }}</ref>
*mitosporic Pucciniales and ''[[incertae sedis]]''
}}

'''Rusts''' are [[fungal plant pathogen]]s of the order '''Pucciniales''' (previously known as '''Uredinales''') causing [[plant fungal disease]]s.

An estimated 168 rust [[genera]] and approximately 7,000 species, more than half of which belong to the genus ''[[Puccinia]]'', are currently accepted.<ref name="How many rust species exist?">{{cite book|last=Mohanan|first=C.|title=Rust Fungi of Kerala |publisher=Kerala Forest Research Institute |location=Kerala, India |year=2010 |pages=148 |isbn=978-81-85041-72-8}}
</ref> Rust fungi are highly specialized plant pathogens with several unique features. Taken as a group, rust fungi are diverse and affect many kinds of plants. However, each species has a range of hosts and cannot be transmitted to non-host plants. In addition, most rust fungi cannot be [[microbial culture|grown easily in pure culture]].

Most species of rust fungi are able to [[Heteroecious|infect two different plant hosts]] in different stages of their life cycle, and may produce up to five [[Morphology (biology)|morphologically]] and [[cytologically]] distinct [[spore]]-producing structures viz., [[spermogonia]], [[aecia]], [[uredinium|uredinia]], [[Telium|telia]], and [[basidia]] in successive stages of reproduction.<ref>{{Cite book|title=eLS|last1=Kolmer|first1=James A|last2=Ordonez|first2=Maria E|last3=Groth|first3=James V|date=2001|publisher=John Wiley & Sons, Ltd|isbn=9780470015902|language=en|doi=10.1002/9780470015902.a0021264|s2cid=1434349 }}</ref>  Each spore type is very host-specific, and can typically infect only one kind of plant.

Rust fungi are [[obligate parasite|obligate plant pathogen]]s that only infect living plants. Infections begin when a spore lands on the plant surface, germinates, and invades its host. Infection is limited to plant parts such as leaves, petioles, tender shoots, stem, fruits, etc.<ref name="How many rust species exist?"/> Plants with severe rust infection may appear stunted, [[chlorotic]] (yellowed), or may display signs of infection such as rust fruiting bodies. Rust fungi grow [[intracellular]]ly, and make spore-producing fruiting bodies within or, more often, on the surfaces of affected plant parts.<ref name="How many rust species exist?"/>  Some rust species form perennial systemic infections that may cause plant deformities such as growth retardation, [[witch's broom]], stem canker, [[gall]]s, or hypertrophy of affected plant parts.

Rusts get their name because they are most commonly observed as deposits of powdery [[rust]]-coloured or brown spores on plant surfaces. The Roman agricultural festival [[Robigalia]] (April 25) has ancient origins in combating wheat rust.<ref name="Evans 2007 p. ">{{cite book | last=Evans | first=R. | title=Utopia Antiqua: Readings of the Golden Age and Decline at Rome | publisher=Taylor & Francis | year=2007 | isbn=978-1-134-48787-5 | url=https://books.google.com/books?id=0YWCAgAAQBAJ | access-date=2018-01-12 | archive-date=2023-10-09 | archive-url=https://web.archive.org/web/20231009003026/https://books.google.com/books?id=0YWCAgAAQBAJ | url-status=live }}</ref>