View source for Stem rust

{{Short description|Fungus disease of cereal crops}}
{{redirect|Red rust|the genus of parasitic thalloid green algae known as red rust|Cephaleuros}}
{{Speciesbox
| image = Stem rust close up.jpg
| genus = Puccinia
| species = graminis
| authority = [[Christiaan Hendrik Persoon|Pers.]], (1794)
| synonyms = See {{Slink||Synonyms}}}}

'''Stem rust''', also known as '''cereal rust''', '''black rust''',<ref name=Singh08 /><ref name=Schumann00/> '''red rust''' or '''red dust''',<ref name=vincent2011/> is caused by the [[fungus]] '''''Puccinia graminis''''', which causes significant disease in [[cereal]] crops. Crop species that are affected by the disease include [[bread wheat]], [[Durum|durum wheat]], [[barley]] and [[triticale]].<ref name=Singh08 /> These diseases have affected cereal farming throughout history. The annual recurrence of stem rust of wheat in North Indian plains was discovered by K. C. Mehta.<ref>{{Cite web|title=History|url=https://www.plantsdiseases.com/p/history.html|last=O|first=Akhtar|website=Plant diseases identification|access-date=2020-05-31}}</ref> Since the 1950s, wheat strains bred to be resistant to stem rust have become available.<ref name=":0">{{Cite journal|last=Bhattacharya|first=Shaoni|date=2017-02-09|title=Deadly new wheat disease threatens Europe's crops|journal=Nature|volume=542|issue=7640|pages=145–146|doi=10.1038/nature.2017.21424|pmid=28179687|bibcode=2017Natur.542..145B|s2cid=4451220}}</ref> [[Fungicide]]s effective against stem rust are available as well.<ref>{{Cite journal|last1=Wanyera|first1=R.|last2=Macharia|first2=J. K.|last3=Kilonzo|first3=S. M.|last4=Kamundia|first4=J. W.|date=2009-08-06|title=Foliar Fungicides to Control Wheat Stem Rust, Race TTKS (Ug99), in Kenya|journal=Plant Disease|volume=93|issue=9|pages=929–932|doi=10.1094/PDIS-93-9-0929|pmid=30754537|doi-access=free}}</ref>

In 1999 a new, more virulent race of stem rust was identified against which most current wheat strains show no resistance. The race was named TTKSK (e.g. isolate [[Ug99]]). An [[epidemic]] of stem rust on wheat caused by race TTKSK spread across [[Africa]], [[Asia]] and the [[Middle East]], causing major concern due to the large numbers of people dependent on wheat for sustenance, thus threatening global [[food security]].<ref name="red alert" />

An outbreak of another virulent race of stem rust, TTTTF, took place in [[Sicily]] in 2016, suggesting that the disease is returning to Europe.<ref name=":0" /> Comprehensive [[genomic]] analysis of ''Puccinia graminis'', combined with plant pathology and climate data, has pointed out the potential of the re-emergence of stem wheat rust in UK.<ref>{{Cite journal|last1=Saunders|first1=Diane G. O.|last2=Wulff|first2=Brande B. H.|last3=Thomas|first3=Jane|last4=Fenwick|first4=Paul M.|
last5=Visser| first5=Botma|last6=Steffenson|first6=Brian|last7=Singh|first7=Ravi P.| last8=Sela| first8=Hanan| last9=Roohparvar|first9=Ramin|date=2018-02-08|title=Potential for re-emergence of wheat stem rust in the United Kingdom|journal=[[Communications Biology]]|volume=1|issue=1|pages=13|doi=10.1038/s42003-018-0013-y|pmid=30271900|pmc=6053080}}</ref><ref>{{Cite journal|last1=Hovmøller|first1=Mogens S.|last2=Pretorius|first2=Zacharias A.|last3=Saunders|first3=Diane G. O.|date=2019-02-04|title=Tackling the re-emergence of wheat stem rust in Western Europe|journal=[[Communications Biology]]|volume=2| issue=1|pages=51|doi=10.1038/s42003-019-0294-9|pmid=30729187|pmc=6361993}}</ref>

{{anchor|History}}

==History==
The fungal ancestors of stem rust have infected grasses for millions of years and wheat crops for as long as they have been grown.<ref name="red alert">Kaplan, Karen (July 22, 2009) "A red alert for wheat". ''[[LA Times]]''</ref> According to Jim Peterson, professor of wheat breeding and genetics at [[Oregon State University]], "Stem rust destroyed more than 20% of U.S. wheat crops several times between 1917 and 1935, and losses reached 9% twice in the 1950s," with the last U.S. outbreak in 1962 destroying 5.2% of the crop.<ref name="red alert"/>

Stem rust has been an ongoing problem dating back to [[Aristotle]]'s time (384–322 BC). An early ancient practice by the Romans was one where they would sacrifice red animals, such as foxes, dogs, and cows, to [[Robigus]] (''fem.'' [[Robigo]]), the rust god. They would perform this ritual in the spring during a festival known as the Robigalia in hopes of the wheat crop being spared from the destruction caused by the rust. Weather records from that time have been reexamined and it has been speculated that the fall of the Roman Empire was due to a string of rainy seasons in which the rust would have been more harsh, resulting in reduced wheat harvests. Laws banning barberry were established in 1660 in [[Rouen]], France. This was due to the fact that European farmers noticed a correlation between barberry and stem rust epidemics in wheat. The law banned the planting of barberry near wheat fields and was the first of its kind.<ref name=Schumann00>{{Cite journal| title=Stem rust of wheat (black rust)| journal=The Plant Health Instructor| author=Schumann, G.L.| author2=Leonard, K. J. |doi=10.1094/PHI-I-2000-0721-01| orig-year=2000|year=2011}}</ref>

The parasitic nature of stem rust was discovered in the 1700s. Two Italian scientists, [[Felice Fontana|Fontana]] and [[Giovanni Targioni Tozzetti|Tozzetti]], first explained the stem rust fungus in wheat in 1767.<ref name=Schumann00 /> Italian scientist [[Giuseppe Maria Giovene]] (1753–1837), in his work {{Lang|it|Lettera al dottor Cosimo Moschettini sulla ruggine}}, also thoroughly studied the stem rust.<ref>{{cite book|author=Giovene, Giuseppe Maria |title=Raccolta di tutte le opere del chiarissimo cavaliere Giuseppe Maria Giovene con note dell'editore Luigi Marinelli Giovene: Memorie fisico agrarie|url=https://books.google.com/books?id=RsF6DcPB7Z0C&pg=152|year=1839|publisher=Cannone|pages=152–}}</ref> Thirty years later it received its name, ''Puccinia graminis'', by [[Christiaan Hendrik Persoon|Persoon]], and in 1854 brothers [[Louis René Tulasne|Louis René]] and [[Charles Tulasne]] discovered the characteristic five-spore stage that is known in some stem rust species. The brothers were also able to make a connection between the red (urediniospore) and black (teliospore) spores as different stages within the life cycle of the same organism, but the rest of the stages remained unknown.<ref name=Schumann00 />

[[Anton de Bary]] later conducted experiments to observe the beliefs of European farmers regarding the relationship between the rust and barberry plants, and after connecting the basidiospores of the basidia stage to barberry, he also identified that the aeciospores in the aecia stage reinfect the wheat host. Upon de Bary's discovery of all five spore stages and their need for barberry as a host, [[John Hubert Craigie|John Craigie]], a Canadian pathologist, identified the function of the [[spermogonium]] in 1927.<ref name=Schumann00 />

Due to the useful nature of both barberry and wheat plants, they were eventually brought to [[North America]] by European colonists. Barberry was used for many things like making wine and jams from the berries to tool handles from the wood. Ultimately, as they did in Europe, the colonists began to notice a relationship between barberry and stem rust epidemics in wheat. Laws were enacted in many [[New England]] colonies, but as the farmers moved west, the problem with stem rust moved with them and began to spread to many areas, creating a devastating epidemic in 1916. It was not until two years later in 1918 that the [[United States]] created a program to remove barberry. The program was one that was supported by state and federal entities and was partly prompted by the threat it posed to food supplies during [[World War I]]. The "war against barberries" was waged and called upon the help of citizens through radio and newspaper advertisements, pamphlets, and fair booths asking for help from all in the attempt to rid the barberry bushes of their existence. Later, in 1975–1980, the program was reestablished under state jurisdiction. Once this happened, a federal quarantine was established against the sale of stem rust susceptible barberry in those states that were part of the program. A barberry testing program was created to ensure that only those species and varieties of barberry that are immune to stem rust will be grown in the quarantine area.<ref name=Schumann00 />

In 1969 two races not detected before in [[Australia]] were found<ref name="Visser-2019">{{cite journal | last1=Visser | first1=Botma | last2=Meyer | first2=Marcel | last3=Park | first3=Robert F. | last4=Gilligan | first4=Christopher A. | last5=Burgin | first5=Laura E. | last6=Hort | first6=Matthew C. | last7=Hodson | first7=David P. | last8=Pretorius | first8=Zacharias A. | title=Microsatellite Analysis and Urediniospore Dispersal Simulations Support the Movement of ''Puccinia graminis'' f. sp. ''tritici'' from Southern Africa to Australia | journal=[[Phytopathology (journal)|Phytopathology]] | publisher=[[American Phytopathological Society]] | volume=109 | issue=1 | year=2019 | issn=0031-949X | doi=10.1094/phyto-04-18-0110-r | pages=133–144| pmid=30028232 | doi-access=free }}</ref> and for decades one hypothesis was an [[Africa]]n origin,<ref name="Visser-2019" /><ref name="Park-2007">{{cite journal | last=Park | first=R. F. | title=Stem rust of wheat in Australia | journal=[[Australian Journal of Agricultural Research]] | publisher=[[CSIRO Publishing]] | volume=58 | issue=6 | year=2007 | issn=0004-9409 | doi=10.1071/ar07117 | page=558}}</ref> and in 2018 DNA analysis confirmed that,<ref name="Park-2007" /> specifically [[South Africa]]n.<ref name="Visser-2019" />

South Africa itself has an ongoing problem with various stem rust outbreaks which requires better response, including an indigenous [[breeding for resistance]] program.<ref name="Park-2007"/>

==Taxonomy==
[[File:Modell von Puccinia graminis (Getreiderost) -Osterloh- -Brendel 10 h, 2-.jpg|thumb|Model of a [[spore]], late 19th century, [[Botanical Museum Greifswald]]]]
There is considerable [[genetic diversity]] within the species ''P.&nbsp;graminis'', and several special forms, ''[[forma specialis]]'', which vary in host range have been identified.

* [[Puccinia graminis f. sp. avenae|''Puccinia graminis'' f. sp. ''avenae'']], [[oat]]
* [[Puccinia graminis f. sp. dactylis|''Puccinia graminis'' f. sp. ''dactylis'']]
* [[Puccinia graminis f. sp. hordei|''Puccinia graminis'' f. sp. ''hordei'']], [[barley]]
* [[Puccinia graminis f. sp. lolii|''Puccinia graminis'' f. sp. ''lolii'']]
* [[Puccinia graminis f. sp. poae|''Puccinia graminis'' f. sp. ''poae'']]
* [[Puccinia graminis f. sp. secalis|''Puccinia graminis'' f. sp. ''secalis'']], [[rye]] and [[barley]]
* ''Puccinia graminis'' f. sp. ''tritici'' / ''Pgt'', [[wheat]] and [[barley]]<ref name="Poudel-et-al-2019">{{cite journal | last1=Sharma Poudel | first1=Roshan | last2=Richards | first2=Jonathan | last3=Shrestha | first3=Subidhya | last4=Solanki | first4=Shyam | last5=Brueggeman | first5=Robert | title=Transcriptome-wide association study identifies putative elicitors/suppressor of ''Puccinia graminis'' f. sp. ''tritici'' that modulate barley rpg4-mediated stem rust resistance | journal=[[BMC Genomics]] | publisher=[[Springer Science+Business Media|Springer Science and Business Media LLC]] | volume=20 | issue=1 | year=2019 | page=985 | issn=1471-2164 | doi=10.1186/s12864-019-6369-7 | pmid=31842749 | pmc=6915985 | doi-access=free }}</ref><ref name="Jin-et-al-1994" /><ref name="Steffenson-et-al-2017">{{cite journal | last1=Steffenson | first1=B. J. | last2=Case | first2=A. J. | last3=Pretorius | first3=Z. A. | last4=Coetzee | first4=V. | last5=Kloppers | first5=F. J. | last6=Zhou | first6=H. | last7=Chai | first7=Y. | last8=Wanyera | first8=R. | last9=Macharia | first9=G. | last10=Bhavani | first10=S. | last11=Grando | first11=S. | title=Vulnerability of Barley to African Pathotypes of ''Puccinia graminis'' f. sp. ''tritici'' and Sources of Resistance | journal=[[Phytopathology (journal)|Phytopathology]] | publisher=[[American Phytopathological Society]] | volume=107 | issue=8 | year=2017 | issn=0031-949X | doi=10.1094/phyto-11-16-0400-r | pages=950–962| pmid=28398875 | doi-access=free | hdl=20.500.11766/12507 | hdl-access=free }} SB [[ORCID]]: [http://orcid.org/0000-0002-4091-2608 0000-0002-4091-2608].</ref>

''P. graminis'' is a member of the phylum [[Basidiomycota]] within the kingdom [[Fungi]]. The characteristic [[Rust (color)|rust color]] on stems and leaves is typical of a general stem rust as well as any variation of this type of fungus. Different from most fungi, the rust variations have five [[spore]] stages and alternate between two hosts. Wheat is the primary host, and [[barberry]] is the alternate host.{{citation needed|date=May 2021}}

The rust is sometimes termed "red rust" or "red dust"<ref name=vincent2011>{{cite web | title=Wheat disease a threat to global food security |first=Michael |last=Vincent | website=ABC News|publisher= [[Australian Broadcasting Corporation]] | date=1 March 2011 | url=https://www.abc.net.au/news/2011-03-01/wheat-disease-a-threat-to-global-food-security/1962800 | access-date=27 May 2021}}</ref><ref name=rainy>{{cite web | title=Red Rust of Wheat | website=Rainy River Record | date=15 May 2012| url=https://www.rainyriverrecord.com/node/14484 | access-date=27 May 2021}}</ref> owing to the spores on the leaf surfaces that range from orange to dark-red in color. Later, the spores change and become dark in color, which gives rise to another common name, "black rust".<ref name=cropscience>{{cite web | title=Wheat Rust Diseases | website=Crop Science US | url=https://www.cropscience.bayer.us/learning-center/articles/wheat-rust-diseases#phcontent_5_divAccordion  | access-date=27 May 2021}}</ref><ref name=Schumann00/>

===''Puccinia graminis'' f. sp. ''tritici''===
{{expand section|date=April 2021}}
The North American race nomenclature system<ref name="CIMMYT-nomen">{{cite web |archive-url=https://web.archive.org/web/20210403172514/https://rusttracker.cimmyt.org/wp-content/uploads/2011/10/NA_nomenclature_code_sheet.pdf |archive-date=2021-04-03 | url=https://rusttracker.cimmyt.org/wp-content/uploads/2011/10/NA_nomenclature_code_sheet.pdf | title=North American Stem Rust Nomenclature Code Sheet | website=[[International Maize and Wheat Improvement Center|CIMMYT]] (International Maize and Wheat Improvement Center)}}</ref><ref name="FAO-race-nomen">{{cite web | title=Rust - Stem: Race Nomenclature | website=United Nations [[Food and Agriculture Organization]] | url=http://www.fao.org/agriculture/crops/rust/stem/stem-pathotypetracker/stem-racenomenclature/en/ | access-date=2021-04-03 | archive-url=https://web.archive.org/web/20210403165453/http://www.fao.org/agriculture/crops/rust/stem/stem-pathotypetracker/stem-racenomenclature/en/ |archive-date=2021-04-03}}</ref><ref name="USDA-ARS-race-ID">{{cite web | title=Race identification |publisher=[[United States Department of Agriculture]] |website=[[Agricultural Research Service]] | url=https://www.ars.usda.gov/midwest-area/stpaul/cereal-disease-lab/docs/cereal-rusts/race-identification/ | access-date=2021-04-03 | url-status=live | archive-url=https://web.archive.org/web/20210403173215/https://www.ars.usda.gov/midwest-area/stpaul/cereal-disease-lab/docs/cereal-rusts/race-identification/ |archive-date=2021-04-03}}</ref> was introduced in 1988 by Roelfs and Martens.<ref name="Roelfs-Martens-1988">{{cite journal | last1=Roelfs | first1=A. P. | last2=Martens | first2=J. W. | title=An International System of Nomenclature for ''Puccinia graminis'' f. sp. ''tritici'' | journal=[[Phytopathology (journal)|Phytopathology]] | publisher=[[American Phytopathological Society]] | volume=78 | issue=5 | year=1988 | issn=0031-949X | doi=10.1094/phyto-78-526 | page=526 | s2cid=85077767}}</ref> This nomenclature is a series of letters each of which indicate virulence/avirulence against one [[plant disease resistance|resistance gene]], as diagnosed by performance against a group of cultivars known to bear that gene.

====Ug99====
''Pgt'' contains many races of wheat diseases, including some of the most significant in the world. [[Ug99]] began as a race ([[Ug99#TTKSK|TTKSK]]) of ''Pgt'' and now has proliferated into a large number of [[Ug99#Races|races of its own]].{{citation needed|date=May 2021}}

The virulent new race, against which most current wheat strains show no resistance, was identified in 1999. The race was named TTKSK (e.g. isolate Ug99), named after the country where it was identified ([[Uganda]]) and the year of its discovery (1999). It spread to [[Kenya]], then [[Ethiopia]], [[Sudan]] and [[Yemen]], and becomes more virulent as it spreads.  An [[epidemic]] of stem rust on wheat caused by race TTKSK spread across [[Africa]], [[Asia]] and the [[Middle East]], causing major concern due to the large numbers of people dependent on wheat for sustenance,<ref name="red alert" /> thus threatening global [[food security]]. In 2011, after it had spread into [[southern Africa]], the [[Bill Gates Foundation]] donated $40''&nbsp;''million towards research into Ug99, to be spent on critical infrastructure in Africa.<ref name=vincent2011/> Scientists are working on breeding strains of wheat that are resistant to UG99. However, wheat is grown in a broad range of environments. This means that breeding programs would have extensive work remaining to get resistance into regionally adapted germplasms even after resistance is identified.<ref name="red alert" /> Similarly, in 2014, a Ug99 race called "Digalu" emerged and devastated the Digalu variety in Ethiopia.<ref name="Hawkins-2021" />{{rp|25}}

====JRCQC====
JRCQC is a race affecting [[Durum]] in [[Ethiopia]].<ref name="Olivera-et-al-2015">{{cite journal | last1=Olivera | first1=Pablo | last2=Newcomb | first2=Maria | last3=Szabo | first3=Les J. | last4=Rouse | first4=Matthew | last5=Johnson | first5=Jerry | last6=Gale | first6=Samuel | last7=Luster | first7=Douglas G. | last8=Hodson | first8=David | last9=Cox | first9=James A. | last10=Burgin | first10=Laura | last11=Hort | first11=Matt | last12=Gilligan | first12=Christopher A. | last13=Patpour | first13=Mehran | last14=Justesen | first14=Annemarie F. | last15=Hovmøller | first15=Mogens S. | last16=Woldeab | first16=Getaneh | last17=Hailu | first17=Endale | last18=Hundie | first18=Bekele | last19=Tadesse | first19=Kebede | last20=Pumphrey | first20=Michael | last21=Singh | first21=Ravi P. | last22=Jin | first22=Yue | title=Phenotypic and Genotypic Characterization of Race TKTTF of ''Puccinia graminis'' f. sp. ''tritici'' that Caused a Wheat Stem Rust Epidemic in Southern Ethiopia in 2013–14 | journal=[[Phytopathology (journal)|Phytopathology]] | publisher=[[American Phytopathological Society]] | volume=105 | issue=7 | year=2015 | issn=0031-949X | doi=10.1094/phyto-11-14-0302-fi | pages=917–928 | pmid=25775107 | s2cid=40448078| doi-access=free}}</ref>

====MCC====
Affects barley.<ref name="Jin-et-al-1994">{{cite journal|last1=Jin|first1=Y|last2=Steffenson|first2=BJ|last3=Miller|first3=JD|year= 1994|title=Inheritance of resistance to pathotypes QCC and MCC of ''Puccinia graminis'' f.sp. ''tritici'' in barley line Q21861 and temperature effects on the expression of resistance|journal=[[Phytopathology (journal)|Phytopathology]]|publisher=[[American Phytopathological Society]]|volume=84|issue=5|pages=452–455|doi=10.1094/Phyto-84-452}}</ref>

====QCC====
Affects barley.<ref name="Jin-et-al-1994" /><ref name="Steffenson-et-al-2017" />

Successfully overwintered in [[Kansas]] in 1989/90, and in [[Texas]] and Kansas in 1990/91, and so was expected to thereafter be a permanent part of the North American ''Pg'' population. Further pathogen adaptation, resulting in widening of the host range, is expected.<ref name="Roelfs-Long-Roberts-1993" />

{{anchor|QCC-2}}

=====QCCJ=====
Synonymous with QCCJB<ref name="Steffenson-et-al-2017" /> or known as QCC-2 by some classifications.

Most common ''Pg'' race in 1991 in the [[United States]], 68% of all ''Pg'' samples, and 67% in 1990. Afflicted spring-sown barley in the northern Great Plains in 1990. Was the first barley stem rust to show up in the United States in 1991, in [[southern Texas]] in [[Uvalde, Texas|Uvalde]]. Thought to be responsible for rusting of wild ''[[Hordeum|Hordea]]'' in the [[Midwestern United States]] and Great Plains, and overall was 94% of ''Pg''s on ''Hordea'' in 1991. 67% of QCCJ was from barley and 95% of ''Pg'' on barley was QCCJ. On wheat, QCCJ was still the most common race but only at 38% of ''Pg''. Continues to threaten barley in the [[Red River Valley]] in [[North Dakota]] and [[Minnesota]]. Higher than normal [[propagule|inoculum]] production in [[South Central Oklahoma]] and the adjacent part of [[North Texas]] before the 1991 season resulted in an epidemic in [[North Central Kansas|North Central]] and northwestern Kansas.<ref name="Roelfs-Long-Roberts-1993">{{cite journal | last1=Roelfs | first1=A. P. | first2=D. L. | last2=Long | first3=J. J. | last3=Roberts | title=Races of ''Puccinia graminis'' in the United States During 1991 | journal=[[Plant Disease (journal)|Plant Disease]] | publisher=[[American Phytopathological Society]] | volume=77 | issue=2 | year=1993 | issn=0191-2917 | doi=10.1094/pd-77-0129 | page=129 | s2cid=88120284}}</ref> [[Virulence|Virulent]] against barley bearing ''Rpg1''. Down to 26% of ''Pg''s afflicting wheat in the US in 1995, 1% in 1996, and not at all in 1997 or 1998. Not found on barley in 1997 but found again in 1998.<ref name="McVey-Long-Roberts-2002">{{cite journal | last1=McVey | first1=D. V. | last2=Long | first2=D. L. | last3=Roberts | first3=J. J. | title=Races of ''Puccinia graminis'' in the United States During 1997 and 1998 | journal=[[Plant Disease (journal)|Plant Disease]] | publisher=[[American Phytopathological Society]] | volume=86 | issue=6 | year=2002 | issn=0191-2917 | doi=10.1094/pdis.2002.86.6.568 | pages=568–572 | pmid=30823225 | s2cid=73493362| doi-access=free }}</ref>

======QCCJB======
The first QCC race (since renamed QCCJ or QCCJB) was detected in the northwest [[Great Plains]] in 1988, and by 1990 was over 90% of ''Pg''s on barley in the United States.<ref name="Steffenson-et-al-2017" /> Also afflicted wheat until a mass switch away from vulnerable cultivars resulted in complete absence in 1997 or 1998.<ref name="McVey-Long-Roberts-2002" /><ref name="Steffenson-et-al-2017" /> Barley virulence is temperature-sensitive: from {{convert|18-20|C|F}} ''rpg4'' and ''Rpg5'' are highly effective, but above {{convert|27|C|F}} they are ineffective. Not necessarily distinguishable from QCCJ, used synonymously by some practitioners.<ref name="Steffenson-et-al-2017" />

=====QCCS=====
Found in the US on wheat in 1997 and 1998 – but only in the West across both years. On barley in 1997 but not 1998.<ref name="McVey-Long-Roberts-2002" />

====QFCS====
25% of ''Pg''s on wheat in 1991. Traces found growing in northwest [[Illinois]] fields, also in 1991.<ref name="Roelfs-Long-Roberts-1993" /> 8% of all ''Pg''s on wheat, barley, and oat in the US in 1997, and 31% in 1998. Displaced the previously dominant [[#TPMK|TPMK]] suddenly in 1998.<ref name="McVey-Long-Roberts-2002" />

====TPMK====
36% of ''Pg'' samples from wheat in 1991 in the United States. Unusually severe in [[southern Illinois]] in the first week of June, and in west [[central Indiana]], in 1991.<ref name="Roelfs-Long-Roberts-1993" /> TPMK was the worst at 69% of ''Pg''s on wheat in 1997 in the United States – being absent only from the southern Great Plains and the west, but then was down to 10% in 1998. In the upper Great Plains it was already declining – to 26% of samples in 1997, and 12% in 1998. In the most fertile areas of the eastern US it was 96% of ''Pg''s in 1997 but then suddenly fell to 29% in 1998. In a few other locations in the US, and overall across the US, this race declined 97–98 in favor of other races, and not because of overall ''Pg'' decline.<ref name="McVey-Long-Roberts-2002" />

===Synonyms===
As listed by [[Species Fungorum]];<ref>{{cite web |title=Species Fungorum - GSD Species |url=https://www.speciesfungorum.org/Names/GSDSpecies.asp?RecordID=159822 |website=www.speciesfungorum.org |access-date=19 August 2023}}</ref>
{{div col}}
*''Aecidium berberidis'' {{Au|Pers. ex J.F. Gmel., Syst. Nat., Edn 13 2(2): 1473 (1792)}}
*''Aecidium berberidis'' var. ''cyathiforme {{Au|Rebent., Prodr. fl. neomarch. (Berolini): 352 (1804)}}
*''Aecidium berberidis var. cylindricum'' {{Au|Rebent., Prodr. fl. neomarch. (Berolini): 352, tab. 3:11a-b (1804)}}
*''Caeoma berberidis'' {{Au|(Pers. ex J.F. Gmel.) Schltdl., Fl. berol. (Berlin) 2: 112 (1824)}}
*''Dicaeoma anthistiriae'' {{Au|(Barclay) Syd., Annls mycol. 20(3/4): 117 (1922)}}
*''Dicaeoma anthoxanthi'' {{Au|(Fuckel) Kuntze, Revis. gen. pl. (Leipzig) 3(3): 467 (1898)}}
*''Dicaeoma graminis'' {{Au|(Pers.) Gray, Nat. Arr. Brit. Pl. (London) 1: 542 (1821)}}
*''Dicaeoma phlei-pratensis'' {{Au|(Erikss. & Henn.) Kuntze, Revis. gen. pl. (Leipzig) 3(3): 470 (1898)}}
*''Dicaeoma vilis'' {{Au|(Arthur) Arthur, Résult. Sci. Congr. Bot. Wien 1905: 344 (1906)}}
*''Epitea dactylidis'' {{Au|G.H. Otth, Mitt. naturf. Ges. Bern 531-552: 88 (1864)}}
*''Lycoperdon berberidis'' {{Au|C.-J. Duval, in Hoppe, Bot. Taschenb.: 257 (1793)}}
*''Puccinia albigensis'' {{Au|Mayor, Revue Mycol., Paris 22(3): 278 (1957)}}
*''Puccinia anthistiriae'' {{Au|Barclay, J. Asiat. Soc. Bengal, Pt. 2, Nat. Sci. 58: 246 (1889)}}
*''Puccinia anthoxanthi'' {{Au|Fuckel, Jb. nassau. Ver. Naturk. 27-28: 15 (1874)}}
*''Puccinia brizae-maximae'' {{Au|T.S. Ramakr., Indian Phytopath. 6: 30 (1954)}}
*''Puccinia cerealis'' {{Au|H. Mart., Prodr. Fl. Mosq., Edn 2: 227 (1817)}}
*''Puccinia culmorum'' {{Au|Schumach., Enum. pl. (Kjbenhavn) 2: 233 (1801)}}
*''Puccinia dactylidis'' {{Au|G.H. Otth, Mitt. naturf. Ges. Bern 531-552: 88 (1864)}}
*''Puccinia dactylidis'' {{Au|Gäum., Ber. schweiz. bot. Ges. 55: 79 (1945)}}
*''Puccinia elymina'' {{Au|Miura, Flora of Manchuria and East Mongolia, III Cryptogams, Fungi (Industr. Contr. S. Manch. Rly 27): 283 (1928)}}
*''Puccinia favargeri'' {{Au|Mayor, Revue Mycol., Paris 22(3): 273 (1957)}}
*''Puccinia graminis'' f. ''macrospora'' {{Au|Baudyš, Lotos 64: 29 (1916)}}
*''Puccinia graminis'' subsp. ''graminicola'' {{Au|Z. Urb., Česká Mykol. 21(1): 14 (1967)}}
*''Puccinia graminis'' subsp. ''major'' {{Au|A.L. Guyot, Massenot & Saccas, Annales de l'École Nationale d'Agriculture de Grignon, sér. 3 5: 142 (1946)}}
*''Puccinia graminis'' var. ''phlei-pratensis'' {{Au|(Erikss. & Henn.) Stakman & Piem., J. Agric. Res., Washington 10: 433 (1917)}}
*''Puccinia graminis'' var. ''stakmanii'' {{Au|A.L. Guyot, Massenot & Saccas, Ann. Ec. Agric. Grignon 5: 145 (1946)}}
*''Puccinia graminis'' var. ''stakmanii'' {{Au|A.L. Guyot, Massenot & Saccas ex Z. Urb., Česká Mykol. 21(1): 14 (1967)}}
*''Puccinia graminis'' var. ''tritici'' {{Au|A.L. Guyot, Massenot & Saccas, Annales de l'École Nationale d'Agriculture de Grignon, sér. 3 5: 145 (1946)}}
*''Puccinia jubata'' {{Au|Ellis & Barthol., Erythea 4: 2 (1896)}}
*''Puccinia linearis'' {{Au|Röhl., Deutschl. Fl. (Frankfurt) 3(3): 132 (1813)}}
*''Puccinia megalopotamica'' {{Au|Speg., Anal. Mus. nac. Hist. nat. B. Aires 6: 224 (1898)}}
*''Puccinia phlei-pratensis'' {{Au|Erikss. & Henn., Z. PflKrankh. 4: 140 (1894)}}
*''Puccinia vilis'' {{Au|Arthur, Bull. Torrey bot. Club 28: 663 (1901)}}
*''Roestelia berberidis'' {{Au|(Pers. ex J.F. Gmel.) Gray, Nat. Arr. Brit. Pl. (London) 1: 534 (1821)}}
*''Uredo frumenti'' {{Au|Sowerby, Col. fig. Engl. Fung. Mushr. (London) 2(no. 13): tab. 140 (1799)}}
{{div col end}}

==Pathology==
The stem rust fungus attacks the parts of the plant that are above ground. Spores that land on green wheat plants form a pustule that invades the outer layers of the stalk.<ref name="red alert"/> Infected plants produce fewer [[Tiller (botany)|tillers]] and set fewer seed, and in cases of severe infection the plant may die. Infection can reduce what is an apparently healthy crop about three weeks before harvest into a black tangle of broken stems and shriveled grains by harvest.<ref name=Singh08>{{Cite journal |last=Singh |first=Ravi P. |author2=Hodson, David |author3=Huerta-Espino, Julio |author4=Jin, Yue |author5=Njau, Peter |author6=Wanyera, Ruth |author7=Herrera-Foessel, Sybil |author8=Ward, Richard W. |display-authors=3 |title=Will Stem Rust Destroy The World's Wheat Crop? |journal=Advances in Agronomy |year=2008 |volume=98 |pages=272–309 |doi=10.1016/S0065-2113(08)00205-8 |url=https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=36520&content=PDF |isbn=9780123743558 |access-date=2018-12-29 |archive-date=2020-11-08 |archive-url=https://web.archive.org/web/20201108063602/https://naldc-legacy.nal.usda.gov/naldc/download.xhtml?id=36520&content=PDF |url-status=dead }}</ref>

Stem rust of cereals causes yield losses in several ways:<ref name=Schumann00 />
* Fungus absorbs nutrients that would otherwise be used for grain development.
* Pustules break through epidermis, which disrupt the plant's control of transpiration and can lead to [[desiccation]] and infection by other fungi. 
* Interference with plant vascular tissue leads to shriveled grains.
* The fungus weakens the stems, which can lead to lodging (falling over). In severe cases lodging can make mechanical harvesting impossible.

==Signs and symptoms==

===On wheat===
[[File:Stem rust on differential lines wheat.jpg|thumb|[[Race differential]] (Infected and uninfected depending on specific [[Disease resistance|resistance gene]]s)|alt=[[Race differential]] (Infected and uninfected leaves, depending on specific [[Disease resistance|resistance gene]]s)]]
Stem rust on wheat is characterized by the presence of uredinia on the plant, which are brick-red, elongated, blister-like pustules that are easily shaken off. They most frequently occur on the leaf sheaths, but are also found on [[Plant stem|stems]], [[Leaf|leaves]], [[glume]]s and [[Awn (botany)|awns]]. On leaves they develop mostly on the underside but may penetrate to the upperside. On leaf sheaths and glumes pustules rupture the epidermis, giving a ragged appearance.<ref name=Singh08 />

Towards the end of the growing season black [[telium|telia]] are produced. For this reason stem rust is also known as "black rust". The telia are firmly attached to the plant tissue.<ref name=Singh08 />

The site of infection is a visible symptom of the disease.

===On barberry===
Pycnia appear on [[barberry]] plants in the spring, usually in the upper leaf surfaces. They are often in small clusters and exude [[pycniospore]]s in a sticky honeydew. Five to ten days later, cup-shaped structures filled with orange-yellow, powdery [[aeciospore]]s break through the lower leaf surface. The aecial cups are yellow and sometimes elongate to extend up to {{convert|5|mm|in|frac=64}} from the leaf surface.<ref name=Schumann00 /> So important is its role in maintenance of prevalence that since the near extermination of the [[alternate host]] from the northern [[Great Plains]] in the United States, epidemics in crops have become rare.<ref name="Roelfs-Long-Roberts-1993" />

==Life cycle==
[[File:Puccina graminis lifecycle.gif|frameless|right]]
Like other ''[[Puccinia]]'' species, ''P.&nbsp;graminis'' is an [[obligate biotroph]] (it colonizes living plant cells) and has a complex life cycle<ref>[https://www.youtube.com/watch?v=AeuP5IYP5HA Animated video of the life cycle of stem rust]</ref> featuring [[alternation of generations]]. The fungus is [[heteroecious]], requiring two hosts to complete its life cycle – the cereal host and the [[alternate host]].<ref name=Schumann00 /> There are many species in ''[[Berberis]]'' and ''[[Mahonia]]'' (and their hybrid genus ''[[Mahoberberis|x Mahoberberis]]'') that are susceptible to stem rust, but the [[Berberis vulgaris|common barberry]] (''B. vulgaris'') is considered to be the most important alternate host.<ref name="Singh08" /> ''P.&nbsp;graminis'' is macrocyclic<ref name="Schumann00" /> (exhibits all five of the [[Rust fungus#Spores|spore types]] that are known for rust fungi<ref name="Peterson74">{{cite journal|last=Peterson|first=Ronald H.|title=The rust fungus life cycle|journal=The Botanical Review|year=1974|volume=40|issue=4|pages=453–513|doi=10.1007/BF02860021|bibcode=1974BotRv..40..453P |s2cid=45598137}}</ref>).

''P. graminis'' can complete its life cycle either with or without barberry (the alternate host).<ref name=Schumann00 />

''P. g. tritici''{{'}}s [[obligately biotrophic]] lifestyle involves the dramatic up-regulation of particular gene transcriptions, constituting its biotrophy genomic features. These genomic regions have parallels in other eukaryotic plant pathogens. These parallels – between these independently evolved and unrelated sets of genes – show a strong and broad pattern of [[convergent evolution]] around the [[plant pathogen]]ic [[lifestyle (biology)|lifestyle]].<ref name="Duplessis-et-al-2011">{{cite journal | last1=Duplessis | first1=S. | last2=Cuomo | first2=C. A. | last3=Lin | first3=Y.-C. | last4=Aerts | first4=A. | last5=Tisserant | first5=E. | last6=Veneault-Fourrey | first6=C. | last7=Joly | first7=D. L. | last8=Hacquard | first8=S. | last9=Amselem | first9=J. | last10=Cantarel | first10=B. L. | last11=Chiu | first11=R. | last12=Coutinho | first12=P. M. | last13=Feau | first13=N. | last14=Field | first14=M. | last15=Frey | first15=P. | last16=Gelhaye | first16=E. | last17=Goldberg | first17=J. | last18=Grabherr | first18=M. G. | last19=Kodira | first19=C. D. | last20=Kohler | first20=A. | last21=Kues | first21=U. | last22=Lindquist | first22=E. A. | last23=Lucas | first23=S. M. | last24=Mago | first24=R. | last25=Mauceli | first25=E. | last26=Morin | first26=E. | last27=Murat | first27=C. | last28=Pangilinan | first28=J. L. | last29=Park | first29=R. | last30=Pearson | first30=M. | last31=Quesneville | first31=H. | last32=Rouhier | first32=N. | last33=Sakthikumar | first33=S. | last34=Salamov | first34=A. A. | last35=Schmutz | first35=J. | last36=Selles | first36=B. | last37=Shapiro | first37=H. | last38=Tanguay | first38=P. | last39=Tuskan | first39=G. A. | last40=Henrissat | first40=B. | last41=Van de Peer | first41=Y. | last42=Rouze | first42=P. | last43=Ellis | first43=J. G. | last44=Dodds | first44=P. N. | last45=Schein | first45=J. E. | last46=Zhong | first46=S. | last47=Hamelin | first47=R. C. | last48=Grigoriev | first48=I. V. | last49=Szabo | first49=L. J. | last50=Martin | first50=F. | title=Obligate biotrophy features unraveled by the genomic analysis of rust fungi, ''Melampsora larici-populina'' and ''Puccinia graminis'' f. sp. ''tritici'' | journal=[[Proceedings of the National Academy of Sciences]] | publisher=[[National Academy of Sciences]] | volume=108 | issue=22 | date=2011-05-02 | issn=0027-8424 | doi=10.1073/pnas.1019315108 | pages=9166–9171| pmid=21536894 | pmc=3107277 | doi-access=free}}</ref>

===Life cycle on barberry===
Due to its cyclical nature, there is no true 'start point' for this process. Here, the production of [[urediniospore]]s is arbitrarily chosen as a start point.

Urediniospores are formed in structures called uredinia, which are produced by fungal [[Mycelium|mycelia]] on the cereal host 1–2 weeks after infection. The urediniospores are [[Dikaryon|dikaryotic]] (contain two un-fused, haploid nuclei in one cell) and are formed on individual stalks within the [[uredinium]]. They are spiny and brick-red. Urediniospores are the only type of spores in the rust fungus life cycle that are capable of infecting the host on which they are produced, and this is therefore referred to as the 'repeating stage' of the life cycle. It is the spread of urediniospores that allows infection to spread from one cereal plant to another.<ref name=Schumann00 /> This phase can rapidly spread the infection over a wide area.

Towards the end of the cereal host's growing season, the mycelia produce structures called telia. Telia produce a type of spore called [[teliospore]]s. These black, thick-walled spores are [[Dikaryon|dikaryotic]]. They are the only form in which ''Puccinia graminis'' is able to overwinter independently of a host.<ref name=Schumann00 />

Each teliospore undergoes [[karyogamy]] (fusion of nuclei) and [[meiosis]] to form four haploid spores called [[basidiospore]]s. This is an important source of genetic recombination in the life cycle. Basidiospores are thin-walled and colourless. They cannot infect the cereal host, but can infect the alternative host (barberry).<ref name=Schumann00 /> They are usually carried to the alternative host by wind.

Once basidiospores arrive on a leaf of the alternative host, they germinate to produce a [[mycelium]] (which is [[haploid]]) that directly penetrates the epidermis and colonises the leaf. Once inside the leaf the mycelium produces specialised infection structures called pycnia. The pycnia produce two types of haploid gametes, the [[pycniospore]]s and the receptive hyphae. The pycniospores are produced in a sticky honeydew that attracts insects. The insects carry pycniospores from one leaf to another. Splashing raindrops can also spread pycniospores. A pycniospore can fertilise a receptive hypha of the opposite [[mating type]], leading to the production of a [[mycelium]] that is [[Dikaryon|dikaryotic]]. This is the sexual stage of the life cycle and cross-fertilisation provides an important source of genetic recombination.<ref name=Schumann00 />

This dikaryotic mycelium then forms structures called [[Aecium|aecia]], which produce a type of dikaryotic spores called [[aeciospore]]s. These have a worty appearance and are formed in chains – unlike the urediniospores that are spiny and are produced on individual stalks. The chains of aeciospores are surrounded by a bell-like enclosure of fungal cells. The aeciospores are able to germinate on the cereal host but not on the alternative host (they are produced on the alternative host, which is usually barberry). They are carried by wind to the cereal host where they germinate and the germ tubes penetrate into the plant. The fungus grows inside the plant as a dikaryotic mycelium. Within 1–2 weeks the mycelium produces uredinia and the cycle is complete.<ref name=Schumann00 />

===Life cycle without barberry===
Since the urediniospores are produced on the cereal host and can infect the cereal host, it is possible for the infection to pass from one year's crop to the next without infecting the alternate host (barberry). For example, infected volunteer wheat plants can serve as a bridge from one growing season to another. In other cases the fungus passes between winter wheat and spring wheat, meaning that it has a cereal host all year round. Since the urediniospores are wind dispersed, this can occur over large distances.<ref name=Schumann00 /> Note that this cycle consists simply of vegetative propagation – urediniospores infect one wheat plant, leading to the production of more urediniospores that then infect other wheat plants.

==Spore dispersal==
''Puccinia graminis'' produces all five of the [[Rust (fungus)#Spores|spore types that are known for rust fungi]].<ref name=Schumann00 />

Spores are typically deposited close to the source, but long-distance dispersal is also well documented<ref name=Singh08 /> commonly out to hundreds of kilometres/miles.<ref name="Gross-2013">{{cite journal | last=Gross | first=Michael | title=Pests on the move | journal=[[Current Biology]] | publisher=[[Cell Press]] | volume=23 | issue=19 | year=2013 | issn=0960-9822 | doi=10.1016/j.cub.2013.09.034 | pages=R855–R857 | pmid=24251330 | s2cid=15559913| doi-access=free | bibcode=2013CBio...23.R855G }}</ref> The following three categories of long-distance dispersal are known to occur:<ref name=Singh08 />
*'''Extremely long-distance dispersal'''
This can occur unassisted (the robust nature of the spores allows them to be carried long distances in the air and then deposited by rain-scrubbing) or assisted (typically on human clothing or infected plant material that is transported between regions).<ref name=Singh08 /> This type of dispersal is rare and is very difficult to predict.<ref name=Singh08 /> This is especially known to rarely occur across thousands of km/mi from South Africa to Western Australia.<ref name="Sounding-Alarm">{{cite report | url=http://bgri.cornell.edu/wp-content/uploads/2020/12/SoundingAlarmGlobalRust.pdf | title=Sounding the Alarm on Global Stem Rust | publisher=[[Borlaug Global Rust Initiative]] | quote-page=4 | quote=Like all...}}</ref><ref name="Watson-et-al-1966">{{cite journal | author1=Watson, I A.|author2= Cass Smith, W. P.|author3=Shipton, W. A.|date=1966|title=Strains of stem and leaf rust on wheat in Western Australia since 1951|journal=Journal of the Department of Agriculture, Western Australia|series=Series 4|volume= 7 |number=8|pages= Article 7 | quote-page=365 | quote=It may be...}}</ref>
*'''Step-wise range expansion'''
This is probably the most common mode of long-distance dispersal and usually occurs within a country or region.<ref name=Singh08 /> 
*'''Extinction and recolonisation'''
This occurs in areas that have unsuitable conditions for year-round survival of ''Puccinia graminis'' – typically temperate regions where hosts are absent during either the winter or summer.<ref name=Singh08 /> Spores overwinter or oversummer in another region and then recolonise when conditions are favorable.<ref name=Singh08 />

{{anchor|Sr|Resistance genes}}

== Wheat stem rust resistance genes ==
A number of stem rust [[R gene|resistance genes]] (Sr genes) have been identified in wheat.<ref name=Singh-et-al-2011 /> Some of them arose in [[bread wheat]] (e.g. ''Sr5'' and ''Sr6''), while others have been bred in from other [[wheat]] species (e.g. ''Sr21'' from ''[[Triticum monococcum|T. monococcum]]'') or from other members of the tribe ''[[Triticeae]]'' (e.g. ''Sr31'' from [[rye]]<ref name="Hawkins-2021" />{{rp|15}} and ''Sr44'' from ''[[Thinopyrum intermedium]]'').

None of the Sr genes provide resistance to all races of stem rust. For instance many of them are ineffective against the [[Ug99]] lineage.<ref name=Singh11>{{cite journal| last=Singh| first=Ravi P.| author2=Hodson, David P. |author3=Huerta-Espino, Julio |author4=Jin, Yue |author5=Bhavani, Sridhar |author6=Njau, Peter |author7=Herrera-Foessel, Sybil |author8=Singh, Pawan K. |author9=Singh, Sukhwinder |author10= Govindan, Velu |title=The Emergence of Ug99 Races of the Stem Rust Fungus is a Threat to World Wheat Production| journal=[[Annual Review of Phytopathology]]| date= 2011| volume=49| issue=1| pages=465–481| doi=10.1146/annurev-phyto-072910-095423| pmid=21568701}} SB [[ORCID]]: [http://orcid.org/0000-0002-4091-2608 0000-0002-4091-2608].</ref> Notably Ug99 has [[virulence]] against ''Sr31'', which was effective against all previous stem rust races. Recently, a new stem rust resistance gene ''Sr59'' from ''[[Secale cereale]]'' was introgressed into wheat, which provides an additional asset for wheat improvement to mitigate yield losses caused by stem rust. Singh et al. (2011) provide a list of known Sr genes and their effectiveness against Ug99.<ref name=Singh11 />

There has been significant uptake of resistant wheat varieties among [[Ethiopia]]n farmers since 2014<ref name="Hodson-et-al-2020">{{cite journal | last1=Hodson | first1=D. P. | last2=Jaleta | first2=M. | last3=Tesfaye | first3=K. | last4=Yirga | first4=C. | last5=Beyene | first5=H. | last6=Kilian | first6=A. | last7=Carling | first7=J. | last8=Disasa | first8=T. | last9=Alemu | first9=S. K. | last10=Daba | first10=T. | last11=Alemayehu | first11=Y. | last12=Badebo | first12=A. | last13=Abeyo | first13=B. | last14=Erenstein | first14=O. | title=Ethiopia's transforming wheat landscape: tracking variety use through DNA fingerprinting | journal=[[Scientific Reports]] | publisher=[[Springer Nature]] | volume=10 | issue=1 | date=2020-10-28 | page=18532 | issn=2045-2322 | doi=10.1038/s41598-020-75181-8 | pmid=33116201 | pmc=7595036}}</ref><ref name="CGIAR-Ethiopian-adoption">{{cite web | title=Press release: Rust-resistant bread wheat varieties widely adopted in Ethiopia, study shows » CGIAR Research Program on WHEAT | website=[[CGIAR]] WHEAT | date=10 November 2020 | url=http://wheat.org/press-release-rust-resistant-bread-wheat-varieties-widely-adopted-in-ethiopia-study-shows/ | access-date=2020-11-18}}</ref> – a great deal of which is thanks to [[CGIAR]] and [[International Maize and Wheat Improvement Center|CIMMYT]] (the International Maize and Wheat Improvement Center).<ref name="adoption-diffusion-CIMMYT">{{cite web | last=Yasabu | first=Simret | title=Shining a brighter light on adoption and diffusion | website=[[International Maize and Wheat Improvement Center|CIMMYT]] (the International Maize and Wheat Improvement Center) | date=2020-12-15 | url=http://www.cimmyt.org/news/shining-a-brighter-light-on-adoption-and-diffusion/ | access-date=2021-01-01}}</ref><ref name="CGIAR-Ethiopian-adoption" />

Although ''Sr5'', ''Sr21'', ''Sr9e'', ''Sr7b'', ''Sr11'', ''Sr6'', ''Sr8a'', ''Sr9g'', ''Sr9b'', ''Sr30'', ''Sr17'', ''Sr9a'', ''Sr9d'', ''Sr10'', ''SrTmp'', <!--- Sr36 intentionally left out because it is in both lists in the cited slide which can't be correct. [[User:Invasive Spices]] --->''Sr38'', and ''SrMcN'' are no longer effective in [[Lebanon]], ''Sr11'', ''Sr24'', and ''Sr31''<!--- Sr36 intentionally left out because it is in both lists in the cited slide which can't be correct. [[User:Invasive Spices]] ---> still are which is diagnostic for the presence of various races of stem rust – but the complete absence of Ug99 specifically – from Lebanon.<ref name="IITA-CGIAR-slide-Yr-Sr">{{Cite AV media|url=http://youtube.com/watch?v=9ksaCvAy_XQ&t=2677 |archive-url=https://ghostarchive.org/varchive/youtube/20211214/9ksaCvAy_XQ |archive-date=2021-12-14 |url-status=live|publisher=[[International Institute of Tropical Agriculture]] / [[CGIAR]] |series=[[CGIAR]] Germplasm Health Webinar series|volume=Phytosanitary Awareness Week |title=(DAY 2) - Phytosanitary Safety for Transboundary pest prevention - Yellow and Black rust population variability|date=2020-11-09|time-caption=Slide at|time=00:44:37|author=Rola El Amil ([[Lebanese Agricultural Research Institute]], [[Lebanon]])}}{{cbignore}}<!--- Sr36 intentionally left out because it is in both lists in the cited slide which can't be correct. [[User:Invasive Spices]] ---></ref>

=== ''Sr9h'' ===
Discovered and found to provide [[Ug99 resistance]] by Rouse ''et al.'', 2014.<ref name="Hawkins-2021">{{cite journal | title=Ug99 Stem Rust – Breaching Wheat's Defences | journal=Plant Pandemic Studies | publisher=[[British Society for Plant Pathology]] | date=2021-01-20 | first=Nichola | last=Hawkins | url=http://www.bspp.org.uk/category/Plant-Pandemic-Studies/ | pages=1–35}}</ref>{{rp|page=24}} However Ug99 [[fungal isolate|isolates]] from [[South Africa]] and [[Zimbabwe]], both in 2010, already had virulence when retested against this new gene.<ref name="Hawkins-2021" />{{rp|page=24}} Both Rouse and Wessels ''et al.'', 2019 find the Ug99 resistance of cv. 'Matlabas' is probably due to this gene. Wessels finds it is present in less than 5% of [[breeding line]]s.<ref name = "9h" >
 {{ Unbulleted list citebundle
    |{{*}} {{ Citation 
              | language    = English
              | doi-access  = free
              | year        = 2019
              | volume      = 103
              | issue       = 9
              | first6      = Zacharias
              | first5      = Maricelis
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              | last6       = Pretorius
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              | last4       = Zurn
              | last3       = Boshoff
              | last2       = Prins
              | last1       = Wessels
              | pages       = 2337–2344
              | title       = Mapping a Resistance Gene to ''Puccinia graminis'' f. sp. ''tritici'' in the Bread Wheat Cultivar 'Matlabas'
              | s2cid       = 146090970
              | pmid        = 31306087
              | publisher   = [[American Phytopathological Society]] (APS)
              | doi         = 10.1094/pdis-10-18-1731-re
              | journal     = [[Plant Disease (journal)|Plant Disease]]
              | issn        = 0191-2917
           }}

    |{{*}} {{ Citation 
              | language    = English
              | year        = 2021
              | publisher   = [[Taylor & Francis]]
              | volume      = 43
              | first4      = Ronald
              | first3      = Zacharias
              | first2      = Robert
              | first1      = Thomas
              | last4       = Depauw
              | last3       = Pretorius
              | last2       = Park
              | last1       = Fetch
              | issue       = sup2
              | pages       = S275–S297
              | s2cid       = 233672540
              | journal     = [[Canadian Journal of Plant Pathology]]
              | issn        = 0706-0661
              | doi         = 10.1080/07060661.2021.1902860
              | title       = Stem rust: its history in Kenya and research to combat a global wheat threat
           | doi-access= free
              | bibcode = 2021CaJPP..43S.275F
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</ref>

=== ''Sr14'' ===
''Sr14'' does not protect seedlings against [[Ug99#TTKSK|TTKSK]]<ref name="Kumar-et-al-2020">{{cite journal | last1=Kumar | first1=Sachin | last2=Fetch | first2=Tom G. | last3=Knox | first3=Ron E. | last4=Singh | first4=Asheesh K. | last5=Clarke | first5=John M. | last6=Depauw | first6=Ron M. | last7=Cuthbert | first7=Richard D. | last8=Campbell | first8=Heather L. | last9=Singh | first9=Davinder | last10=Bhavani | first10=Sridhar| last11=Pozniak | first11=Curtis J. | last12=Meyer | first12=Brad | last13=Clarke | first13=Fran R. | title=Mapping of Ug99 stem rust resistance in Canadian durum wheat | journal=[[Canadian Journal of Plant Pathology]] | publisher=[[Informa]] UK Limited | date=2020-11-19 | volume=43 | issue=4 | pages=599–611 | issn=0706-0661 | doi=10.1080/07060661.2020.1843073 | doi-access=free}} SB [[ORCID]]: [http://orcid.org/0000-0002-4091-2608 0000-0002-4091-2608].</ref> but does provide moderate resistance at later stages.<ref name="Kumar-et-al-2020" /> It is effective against [[Ug99#TTKST|TTKST]].<ref name="Kumar-et-al-2020" />

=== ''Sr22'' ===
There is considerable variation among ''Sr22'' alleles, with some conferring resistance and some susceptibility.<ref name="Hatta-et-al-2020">{{cite journal | last1=Hatta | first1=Muhammad Asyraf Muhammad | last2=Ghosh | first2=Sreya | last3=Athiyannan | first3=Naveenkumar | last4=Richardson | first4=Terese | last5=Steuernagel | first5=Burkhard | last6=Yu | first6=Guotai | last7=Rouse | first7=Matthew N. | last8=Ayliffe | first8=Michael | last9=Lagudah | first9=Evans S. | last10=Radhakrishnan | first10=Guru V. | last11=Periyannan | first11=Sambasivam K. | last12=Wulff | first12=Brande B. H. | title=Extensive Genetic Variation at the Sr22 Wheat Stem Rust Resistance Gene Locus in the Grasses Revealed Through Evolutionary Genomics and Functional Analyses | journal=[[Molecular Plant-Microbe Interactions]] | publisher=[[American Phytopathological Society]] | volume=33 | issue=11 | year=2020 | issn=0894-0282 | doi=10.1094/mpmi-01-20-0018-r | pages=1286–1298| pmid=32779520 | doi-access=free}} MAMH [[ORCID]]: [http://orcid.org/0000-0002-8952-5684 0000-0002-8952-5684] [[Scopus]]: [http://www.scopus.com/authid/detail.uri?authorId=57189640847 57189640847].</ref>

=== ''Sr27'' ===
''Sr27''<ref name="Sr27-GlobalRust">{{cite web | title=''Sr27'' | website=[[Borlaug Global Rust Initiative]] (BGRI) | url=http://globalrust.org/gene/sr27 | access-date=2021-07-24}}</ref> is originally from [[rye]]<ref name="Singh-et-al-2011">{{cite journal | last1=Singh | first1=Ravi P. | last2=Hodson | first2=David P. | last3=Huerta-Espino | first3=Julio | last4=Jin | first4=Yue | last5=Bhavani | first5=Sridhar | last6=Njau | first6=Peter | last7=Herrera-Foessel | first7=Sybil | last8=Singh | first8=Pawan K. | last9=Singh | first9=Sukhwinder | last10=Govindan | first10=Velu | title=The Emergence of Ug99 Races of the Stem Rust Fungus is a Threat to World Wheat Production | journal=[[Annual Review of Phytopathology]] | publisher=[[Annual Reviews (publisher)|Annual Reviews]] | volume=49 | issue=1 | date=2011-09-08 | issn=0066-4286 | doi=10.1146/annurev-phyto-072910-095423 | pages=465–481| pmid=21568701|id=SB [[ORCID]]: [http://orcid.org/0000-0002-4091-2608 0000-0002-4091-2608]}}</ref> ([[Imperial Rye]]),<ref name="Park-Wellings-2012">{{cite journal | last1=Park | first1=Robert F. | last2=Wellings | first2=Colin R. | title=Somatic Hybridization in the Uredinales | journal=[[Annual Review of Phytopathology]] | publisher=[[Annual Reviews (publisher)|Annual Reviews]] | volume=50 | issue=1 | date=2012-09-08 | issn=0066-4286 | doi=10.1146/annurev-phyto-072910-095405 | pages=219–239| pmid=22920559 }}</ref> now ({{as of|2021|lc=yes}}) widely found in [[triticale]] and rarely in hexaploid wheat.<ref name="Upadhyaya-et-al-2021">{{cite journal|last1=Upadhyaya|first1=Narayana M.|last2=Mago|first2=Rohit|last3=Panwar|first3=Vinay|last4=Hewitt|first4=Tim|last5=Luo|first5=Ming|last6=Chen|first6=Jian|last7=Sperschneider|first7=Jana|last8=Nguyen-Phuc|first8=Hoa|last9=Wang|first9=Aihua|last10=Ortiz|first10=Diana|last11=Hac|first11=Luch|last12=Bhatt|first12=Dhara|last13=Li|first13=Feng|last14=Zhang|first14=Jianping|last15=Ayliffe|first15=Michael|last16=Figueroa|first16=Melania|last17=Kanyuka|first17=Kostya|last18=Ellis|first18=Jeffrey G.|last19=Dodds|first19=Peter N.|title=Genomics accelerated isolation of a new stem rust avirulence gene–wheat resistance gene pair|journal=[[Nature Plants]]|publisher=[[Nature Research]]|year=2021|volume=7|issue=9|pages=1220–1228|issn=2055-0278|doi=10.1038/s41477-021-00971-5|pmid=34294906|bibcode=2021NatPl...7.1220U |s2cid=236199741|url=https://repository.rothamsted.ac.uk/download/911a82b1b12af18ce55d120f48f3568494a06549fc42318ed814d03d057c0e37/4800766/10378_1_supp_129049_q96vf9_convrt.pdf}}</ref> Located on the 3A chromosome arm,<ref name="Sr27-GlobalRust" /> originally from 3R.<ref name="McIntosh-et-al-1995">{{cite book | last1=McIntosh | first1=RA | last2=Wellings | first2=CR | last3=Park | first3=RF | title=Wheat Rusts - An Atlas of Resistance Genes | publisher=[[Springer Publishing|Springer]] | isbn=9789401040419 | date=1995}}</ref> Virulence has been observed in field ''[[Puccinia graminis f. sp. striiformis|Pgs]]'' and in an artificial ''Pgt'' {{times}} ''Pgs''.<ref name="Park-Wellings-2012" /> When successful, ''Sr27'' is among the few ''Sr''s that does not allow the underdeveloped [[uredinia]] and slight degree of sporulation commonly allowed by most ''Sr''s.<ref name="Singh-et-al-2011" /> Instead there are [[necrotic]] or [[chlorotic]] flecks.<ref name="Roelfs-1988">{{cite journal | last=Roelfs | first=A P | title=Genetic Control of Phenotypes in Wheat Stem Rust | journal=[[Annual Review of Phytopathology]] | publisher=[[Annual Reviews (publisher)|Annual Reviews]] | volume=26 | issue=1 | year=1988 | issn=0066-4286 | doi=10.1146/annurev.py.26.090188.002031 | pages=351–367}}</ref> ''Pgt'' virulent on wheat with this gene was found in [[Kenya]] in 1972.<ref name="McIntosh-et-al-1995" /> Deployment in triticale in [[New South Wales]] and [[Queensland]], Australia, rapidly produced virulence between 1982 and 1984 – the first virulence on this gene in the world.<ref name="McIntosh-Brown-1997">{{cite journal | last1=McIntosh | first1=R. A. | last2=Brown | first2=G. N. | title=Anticipatory Breeding for Resistance to Rust Diseases in Wheat | journal=[[Annual Review of Phytopathology]] | publisher=[[Annual Reviews (publisher)|Annual Reviews]] | volume=35 | issue=1 | year=1997 | issn=0066-4286 | doi=10.1146/annurev.phyto.35.1.311 | pages=311–326| pmid=15012526 }}</ref><ref name="Singh-et-al-2011" /><ref name="McIntosh-et-al-1995" /> (This was especially associated with the cultivar Coorong.)<ref name="McIntosh-Brown-1997" /><ref name="Johnson-1984">{{cite journal | last=Johnson | first=R | title=A Critical Analysis of Durable Resistance | journal=[[Annual Review of Phytopathology]] | publisher=[[Annual Reviews (publisher)|Annual Reviews]] | volume=22 | issue=1 | year=1984 | issn=0066-4286 | doi=10.1146/annurev.py.22.090184.001521 | pages=309–330}}</ref> Therefore, CIMMYT's triticale offerings were tested and many were found to depend solely on ''Sr27''.<ref name="Johnson-1984" /><ref name="McIntosh-et-al-1995" /> Four years later, in 1988, virulence was found in [[South Africa]]. ''Sr27'' has become less common in CIMMYT triticales since the mid-'80s.<ref name="McIntosh-et-al-1995" />

=== ''Sr31'' ===
Ug99 is virulent against ''Sr31'', which was effective against all previous stem rust races.<ref name=Singh11 />

=== ''Sr33'' ===
An [[introgression]] from a wild wheat ''[[Aegilops tauschii]]'' [[ortholog]]ous to ''Mla'' in [[barley]]. Confers broad resistance to multiple races including [[Ug99]].<ref name="Periyannan-et-al-2013">{{cite journal | last1=Periyannan | first1=Sambasivam | last2=Moore | first2=John | last3=Ayliffe | first3=Michael | last4=Bansal | first4=Urmil | last5=Wang | first5=Xiaojing | last6=Huang | first6=Li | last7=Deal | first7=Karin | last8=Luo | first8=Mingcheng | last9=Kong | first9=Xiuying | last10=Bariana | first10=Harbans | last11=Mago | first11=Rohit | last12=McIntosh | first12=Robert | last13=Dodds | first13=Peter | last14=Dvorak | first14=Jan | last15=Lagudah | first15=Evans | title=The Gene ''Sr33'', an Ortholog of Barley ''Mla'' Genes, Encodes Resistance to Wheat Stem Rust Race Ug99 | journal=[[Science (journal)|Science]] | publisher=[[American Association for the Advancement of Science]] | volume=341 | issue=6147 | date=2013-06-27 | issn=0036-8075 | doi=10.1126/science.1239028 | pages=786–788 | s2cid=206549297 | pmid=23811228| bibcode=2013Sci...341..786P | doi-access=free }}</ref><ref name="Gross-2013" />

{{ Anchor | AvrSr35 }}

=== ''Sr35'' ===
''Sr35'' is an [[introgression]] from ''[[einkorn wheat|Triticum monococcum]]'' conferring some resistance.<ref name="Gross-2013" /> ''AvrSr35'' – a ''Pgt'' gene so named because it was discovered causing [[avirulence]] on ''Sr35'' – is the ancestral allele to all ''Pgt'' alleles that are virulent on ''Sr35''. ''AvrSr35'' came first, followed by the selective pressure of widespread adoption of ''Sr35'' wheat races, followed by the evolution of virulence on ''Sr35'' by way of nonfunctionalization mutations of ''AvrSr35''.<ref name="Salcedo-et-al-2017">{{cite journal | last1=Salcedo | first1=Andres | last2=Rutter | first2=William | last3=Wang | first3=Shichen | last4=Akhunova | first4=Alina | last5=Bolus | first5=Stephen | last6=Chao | first6=Shiaoman | last7=Anderson | first7=Nickolas | last8=De Soto | first8=Monica Fernandez | last9=Rouse | first9=Matthew | last10=Szabo | first10=Les | last11=Bowden | first11=Robert L. | last12=Dubcovsky | first12=Jorge | last13=Akhunov | first13=Eduard | title=Variation in the AvrSr35gene determines Sr35 resistance against wheat stem rust race Ug99 | journal=[[Science (journal)|Science]] | publisher=[[American Association for the Advancement of Science]] (AAAS) | volume=358 | issue=6370 | date=2017-12-21 | issn=0036-8075 | doi=10.1126/science.aao7294 | pages=1604–1606 | pmid=29269474 | pmc=6518949 | bibcode=2017Sci...358.1604S | s2cid=206664159| doi-access=free}}</ref>

=== ''Sr59'' ===
Recently, a new stem rust resistance gene ''Sr59'' from ''[[Secale cereale]]'' was introgressed into wheat, which provides an additional asset for wheat improvement to mitigate yield losses caused by stem rust.<ref name=Singh11 />

=== ''Sr62'' ===
An NLR (or NB-LRR, or [[R gene]]) from ''[[Aegilops sharonensis]]'', one of only three [[wheat disease resistance gene|resistance genes]] from that species.<ref name="As-identification-Sr62" /> Was discovered by Yu ''et al.'', 2017 and then [[introgressed]] into [[hexaploid wheat|hexaploid]] by Millet ''et al.'', 2017.<ref name="As-identification-Sr62" /> ''Sr62'' [[encoding (gene translation)|encodes]] for a unique [[tandem protein kinase]] which is composed of [[protein domain|domains]] which are common among plants.<ref name="As-identification-Sr62" /> Yu ''et al.'', 2022 <ref name="As-identification-Sr62">
   {{Unbulleted list citebundle
      |{{*}} {{cite journal | year=2022 | issue=1 | volume=13 | publisher=[[Springer Science and Business Media LLC]] | issn=2041-1723 | journal=[[Nature Communications]] | last1=Yu | first1=Guotai | last2=Matny | first2=Oadi | last3=Champouret | first3=Nicolas | last4=Steuernagel | first4=Burkhard | last5=Moscou | first5=Matthew J. | last6=Hernández-Pinzón | first6=Inmaculada | last7=Green | first7=Phon | last8=Hayta | first8=Sadiye | last9=Smedley | first9=Mark | last10=Harwood | first10=Wendy | last11=Kangara | first11=Ngonidzashe | last12=Yue | first12=Yajuan | last13=Gardener | first13=Catherine | last14=Banfield | first14=Mark J. | last15=Olivera | first15=Pablo D. | last16=Welchin | first16=Cole | last17=Simmons | first17=Jamie | last18=Millet | first18=Eitan | last19=Minz-Dub | first19=Anna | last20=Ronen | first20=Moshe | last21=Avni | first21=Raz | last22=Sharon | first22=Amir | last23=Patpour | first23=Mehran | last24=Justesen | first24=Annemarie F. | last25=Jayakodi | first25=Murukarthick | last26=Himmelbach | first26=Axel | last27=Stein | first27=Nils | last28=Wu | first28=Shuangye | last29=Poland | first29=Jesse | last30=Ens | first30=Jennifer | last31=Pozniak | first31=Curtis | last32=Karafiátová | first32=Miroslava | last33=Molnár | first33=István | last34=Doležel | first34=Jaroslav | last35=Ward | first35=Eric R. | last36=Reuber | first36=T. Lynne | last37=Jones | first37=Jonathan D. G. | last38=Mascher | first38=Martin | last39=Steffenson | first39=Brian J. | last40=Wulff | first40=Brande B. H. | s2cid=247713750 | pmid=35338132 | pmc=8956640 | doi=10.1038/s41467-022-29132-8 | title=Aegilops sharonensis genome-assisted identification of stem rust resistance gene ''Sr62''| page=1607 | bibcode=2022NatCo..13.1607Y }}

      |{{*}} {{cite journal | year=2022 | volume=68 | publisher=[[Elsevier]] | last2=Singh | last1=Sinha | issn=1369-5266 | journal=[[Current Opinion in Plant Biology]] | first1=Arunima | first2=Lovepreet | last3=Rawat | title=Current understanding of atypical resistance against fungal pathogens in wheat | first3=Nidhi | s2cid=249729162 | pmid=35716636 | page=102247 | doi=10.1016/j.pbi.2022.102247| doi-access=free | bibcode=2022COPB...6802247S }}
      |{{*}} {{cite journal | issue=9 | volume=65 | year=2022 | publisher=[[Springer Science and Business Media LLC]]| issn=1674-7305 | journal=[[Science China Life Sciences]] | last1=Xiao | first1=Jun | last2=Liu | first2=Bao | last3=Yao | first3=Yingyin | last4=Guo | first4=Zifeng | last5=Jia | first5=Haiyan | last6=Kong | first6=Lingrang | last7=Zhang | first7=Aimin | last8=Ma | first8=Wujun | last9=Ni | first9=Zhongfu | last10=Xu | first10=Shengbao | last11=Lu | first11=Fei | last12=Jiao | first12=Yuannian | last13=Yang | first13=Wuyun | last14=Lin | first14=Xuelei | last15=Sun | first15=Silong | last16=Lu | first16=Zefu | last17=Gao | first17=Lifeng | last18=Zhao | first18=Guangyao | last19=Cao | first19=Shuanghe | last20=Chen | first20=Qian | last21=Zhang | first21=Kunpu | last22=Wang | first22=Mengcheng | last23=Wang | first23=Meng | last24=Hu | first24=Zhaorong | last25=Guo | first25=Weilong | last26=Li | first26=Guoqiang | last27=Ma | first27=Xin | last28=Li | first28=Junming | last29=Han | first29=Fangpu | last30=Fu | first30=Xiangdong | last31=Ma | first31=Zhengqiang | last32=Wang | first32=Daowen | last33=Zhang | first33=Xueyong | last34=Ling | first34=Hong-Qing | last35=Xia | first35=Guangmin | last36=Tong | first36=Yiping | last37=Liu | first37=Zhiyong | last38=He | first38=Zhonghu | last39=Jia | first39=Jizeng | last40=Chong | first40=Kang | s2cid=251842538 | pmid=36018491 | pages=1718–1775 | doi=10.1007/s11427-022-2178-7 | title=Wheat genomic study for genetic improvement of traits in China|id=[[Chinese Academy of Sciences]]+[[National Natural Science Foundation of China]]}}
   }}
</ref>

===''SrTmp''===
Originally from the widespread Ethiopian '{{Vanchor|Digalu}}'.<ref name="Continued-Threat" /> Resistant to [[Ug99]], susceptible to {{Slink||TKTTF}}.<ref name="Continued-Threat">{{cite journal|issue=7|year=2015|last1=Singh|first1=Ravi|last2=Hodson|first2=David|last3=Jin|first3=Yue|last4=Lagudah|first4=Evans|last5=Ayliffe|first5=Michael|last6=Bhavani|first6=Sridhar|last7=Rouse|first7=Matthew|last8=Pretorius|first8=Zacharias|last9=Szabo|first9=Les|last10=Huerta-Espino|first10=Julio|last11=Basnet|first11=Bhoja|last12=Lan|first12=Caixia|pages=872–884|volume=105|last13=Hovmoller|first13=Mogens|s2cid=205345605|pmid=26120730|doi=10.1094/phyto-01-15-0030-fi|journal=[[Phytopathology (journal)|Phytopathology]]|issn=0031-949X|publisher=[[American Phytopathological Society]] (APS)|title=Emergence and Spread of New Races of Wheat Stem Rust Fungus: Continued Threat to Food Security and Prospects of Genetic Control|doi-access=free}}</ref>

== Weaponization ==
{{main|M115 bomb}}
In the 1950s, the [[United States Air Force]] developed Operation Steelyard, a plan to drop wheat stem rust mixed with feathers over wheat farms in the [[Soviet Union]]. If the plan were enacted, [[Boeing B-29 Superfortress]] bombers would drop 500-pound [[M115 bomb]]s over Soviet farms, with the intention of destroying up to 50% of the Soviet winter wheat harvest.<ref>{{cite book |last1=Kirby |last2=Carus |date=2020 |editor1-last= Mauroni |editor2-last=Norton |title= Agroterrorism: National Defense Assessment, Strategies, and Capabilities |publisher=U.S. Air Force Center for Strategic Deterrence Studies |page=9 |chapter=Agroterrorism Perspectives |url=https://www.airuniversity.af.edu/Portals/10/CSDS/books/Agroterror%20book%20final.pdf }}</ref>

==Future==
Alone amongst cereals, [[rice]] is naturally immune to rusts. If a genetic source of this resistance could be identified, [[genetically modified wheat|transgenic wheats]] with rice as the [[gene donor]] could be the future.<ref name="no-rust">{{cite news | url=http://ricetoday.irri.org/no-rust-for-rice/ | first=Linda | last=McCandless | date=2011 | title=No rust for rice | journal=[[Rice Today]]| volume=10 | issue=1 | pages=38–39 | publisher=[[International Rice Research Institute]] (IRRI) ([[CGIAR]]'s Research Program on Rice)}}</ref><ref name="rice-Plantwise">{{cite web | title=Does rust-free rice hold the secret? | website=The Plantwise Blog | publisher=CABI ([[Centre for Agriculture and Bioscience International]]) | date=2011-02-28 | url=http://blog.plantwise.org/2011/02/28/does-rust-free-rice-hold-the-secret/ | access-date=2021-04-10 | first=Katherine | last=Cameron}}</ref>

==See also==
*[[Chilean wheat cycle]]
*[[List of Puccinia species|List of ''Puccinia'' species]]

==References==
{{Reflist}}

==Further reading==
* {{Cite journal|title=A pathotype of ''Puccinia graminis'' f. sp. ''tritici'' on ''Sr24'' in India|last1=Bhardwaj|first1=S.C.|last2=Nyar|first2=S.K.|last3=Prashar|first3=M.|last4=Kumar|first4=J|last5=Menon|first5=M.K.|last6=Singh|first6=S.B.|journal=[[Cereal Rusts and Powdery Mildews Bulletin]]|year=1990|pages=35–38}}

==External links==
*[https://globalrust.org/ Borlaug Global Rust Initiative]
*[https://www.fao.org/agriculture/crops/rust/stem/en/ Stem rust] by FAO (the [[Food and Agriculture Organization]] of the United Nations
*[https://www.youtube.com/globalrust Animation of stem rust life cycle]
*{{cite web |title=Norwich Rust Group |website=[[Norwich Rust Group]] |url=http://www.norwichrustgroup.com/ |archive-url=https://web.archive.org/web/20150313041327/http://www.norwichrustgroup.com/ |url-status=dead |archive-date=March 13, 2015 |access-date=2020-12-18 }}
* {{cite web |title=Stem Rust |url=http://www.wheat-rust-genomics.com/stem-rust/ |access-date=2021-05-26}}

{{Taxonbar|from=Q1342327}}

[[Category:Cereal diseases]]
[[Category:Puccinia]]
[[Category:Fungi described in 1794]]