scholarly journals First Report of Puccinia graminis f. sp. tritici Races with Virulence to Wheat Stem Rust Resistance Genes Sr31 and Sr24 in Eritrea

Plant Disease ◽  
2011 ◽  
Vol 95 (12) ◽  
pp. 1591-1591 ◽  
Author(s):  
A. Wolday ◽  
T. Fetch ◽  
D. P. Hodson ◽  
W. Cao ◽  
S. Briere
Keyword(s):  
Stem Rust ◽  
Range Expansion ◽  
The United States ◽  
Eastern Africa ◽  
Wheat Crop ◽  
Limiting Factor ◽  
Puccinia Graminis ◽  
Migration Routes ◽  
Wheat Stem Rust ◽  
Western Asia

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, has historically been a major limiting factor in wheat production. Identification of isolate Ug99 in Uganda in 1999 highlighted the vulnerability of a large proportion of the global wheat crop and raised international concerns. Since initial detection, seven races have been identified in the Ug99 lineage and occurrence has been confirmed in nine countries (4). During rust surveys of Eritrea undertaken in October 2010, stem rust was found to be widespread throughout the highland wheat-growing areas. Presence of P. graminis f. sp. tritici was recorded in 95% of the 92 cereal fields surveyed, with high disease severity (>40%) recorded at 50 sites. Collected stem rust samples were analyzed for race identity in a level 3 biocontainment laboratory in Canada. Nine collections yielded viable spores for infection studies. Virulence analysis with 20 differentials in the letter-code nomenclature system (1) identified two races from repeated experiments; TTKST (four confirmed isolates) and PTKST (five confirmed isolates). Both races belong to the Ug99 lineage and both exhibit combined Sr31 and Sr24 virulence. TTKST and PTKST differ only in their virulence or avirulence to Sr21, respectively. This first confirmation of TTKST and PTKST in Eritrea is important because it represents further geographical spread of Ug99-related races. Since first detection of a Sr24 variant of Ug99 (race TTKST) in Kenya in 2006 (1), these variants have become the predominant P. graminis f. sp. tritici pathotypes in most of eastern Africa. Race TTKST caused epidemics in Kenya in 2007, and race PTKST was first detected in Ethiopia the same year (T. Fetch, unpublished data). Recent detection of race PTKST in three additional southern Africa countries (South Africa, Zimbabwe, and Mozambique [2,3]) indicates on-going range expansion within the African continent. Sr24-virulent variants of Ug99 are a cause for concern since a high frequency of cultivars from South America, Australia, the United States, and the CIMMYT are known to possess the Sr24 resistance gene. On the basis of observed occurrence and postulated migration routes of the original Ug99 (race TTKSK), the confirmed presence of TTKST and PTKST in Eritrea increases the possibility for range expansion out of Africa by crossing the Red Sea and into the Arabian Peninsula. Future spread of TTKST and PTKST to western Asia is considered highly likely. References: (1) Y. Jin et al. Plant Dis. 92:923, 2008. (2) F. Mukoyi et al. Plant Dis. 95:1188, 2011. (3) Z. A. Pretorius et al. Plant Dis. 94:784, 2010. (4) R. P. Singh et al. Annu. Rev. Phytopathol. 49:465, 2011.

scholarly journals Prevalence and Distribution of Common Barberry, the Alternate Host of Puccinia graminis, in Minnesota

Plant Disease ◽  
2005 ◽  
Vol 89 (2) ◽  
pp. 159-163 ◽  
Author(s):  
P. D. Peterson ◽  
K. J. Leonard ◽  
J. D. Miller ◽  
R. J. Laudon ◽  
T. B. Sutton
Keyword(s):  
United States ◽  
Stem Rust ◽  
Active Sites ◽  
The United States ◽  
Puccinia Graminis ◽  
Alternate Host ◽  
Wheat Stem Rust ◽  
State Program ◽  
Cereal Production ◽  
Active Class

A federal and state program operated from 1918 until the 1980s to eradicate common barberry (Berberis vulgaris), the alternate host of Puccinia graminis, from the major areas of cereal production in the United States. Over 500 million bushes were destroyed nationally during the program, approximately 1 million in Minnesota. Some sites in Minnesota where barberry bushes were destroyed remained in the “active” class when eradication was phased out in the 1980s. Active sites were defined as those on which there was still a possibility of emergence of barberry seedlings or sprouts arising from the parent bush. In the present study, from 1998 to 2002, 72 of the approximately 1,200 active sites in Minnesota were surveyed. Areas within 90 m of mapped locations of previously destroyed bushes were searched carefully at each site. Reemerged barberry plants were found on 32 sites. The reproductive status and GPS coordinates were recorded for each reemerged bush. More than 90% of the barberry bushes were found in counties with less than 400 ha of wheat per county, mostly in southeastern Minnesota, but one bush was found in a major wheat-producing county in northwestern Minnesota. Reemergence of barberry may serve as a source of new wheat stem rust races in future epidemics.

scholarly journals Races of Puccinia graminis in the United States During 1997 and 1998

Plant Disease ◽  
2002 ◽  
Vol 86 (6) ◽  
pp. 568-572 ◽  
Author(s):  
D. V. McVey ◽  
D. L. Long ◽  
J. J. Roberts
Keyword(s):  
United States ◽  
Stem Rust ◽  
The United States ◽  
Puccinia Graminis ◽  
Yield Losses ◽  
Wheat Stem Rust ◽  
The West ◽  
East Central ◽  
Central Texas ◽  
Wheat Lines

Wheat stem rust caused negligible yield losses in 1997 and 1998. Overwintering sites were found in central and east-central Louisiana in 1997, and in northwestern Florida, northeastern Louisiana, and central Texas in 1998. Race Pgt-TPMK predominated in 1997 with 69% of 100 isolates with race RCRS next at 11%. In 1998, race RCRS predominated with 55% of 132 isolates, and TPMK occurred at 10%. Race QFCS occurred at 8% in 1997 and 31% in 1998. Races QCCS and QTHJ were found in 1997, and races QFBS, RKMQ, RKQQ, and RCMS were found in 1998. Race QCCJ, virulent to barley with the Rpg1 gene for stem rust resistance, was not found from wheat in 1997 or 1998. No virulence was found to wheat lines with Sr 13, 22, 24, 25, 26, 27, 29, 30, 31, 32, 37, Gt, or Wld-1. Oat stem rust was found earlier in 1997 than 1998, but was more widespread in 1998. Race NA27, virulent to Pg-1, -2, -3, -4, and -8, was the predominant race in the United States in 1997 (79% of 116 isolates) and again in 1998 (79% of 116 isolates). NA16, virulent to Pg-1, -3, and -8, was found in the south (1997 and 1998), and NA5, virulent to Pg-2 and -15, and NA10, virulent to Pg-2, -3, and -15, were found in the west (1997).

scholarly journals Detection of Virulence to Wheat Stem Rust Resistance Gene Sr31 in Puccinia graminis. f. sp. tritici in Uganda

Plant Disease ◽  
2000 ◽  
Vol 84 (2) ◽  
pp. 203-203 ◽  
Author(s):  
Z. A. Pretorius ◽  
R. P. Singh ◽  
W. W. Wagoire ◽  
T. S. Payne
Keyword(s):  
South African ◽  
Stem Rust ◽  
Rust Resistance ◽  
The United States ◽  
Chromosome Translocation ◽  
Research Station ◽  
Puccinia Graminis ◽  
Wheat Stem Rust ◽  
Light Mineral ◽  
Infection Types

In much of the world, resistance to stem rust in wheat, caused by Puccinia graminis f. sp. tritici, is based at least in part on the gene Sr31. During February 1999, high levels of stem rust infection were observed on entries in wheat (Triticum aestivum) grown in a nursery at Kalengyere Research Station in Uganda. Because several of the rusted entries were known to carry the 1BL-1RS chromosome translocation containing the Sr31, Lr26, and Yr9 genes for rust resistance, virulence to Sr31 was suspected. Urediniospores, collected in bulk from rusted stems of seven entries containing Sr31, were suspended in light mineral oil and sprayed on primary leaves of 7-day-old seedlings of South African wheat cv. Gamtoos (=Veery #3, pedigree: Kvz/Buho‘S’//Kal/BB). Plants were kept overnight at 19 to 21°C in a dew chamber before placement in a greenhouse at 18 to 25°C. After ≈14 days, urediniospores were collected from large, susceptible-type stem rust pustules and subsequently increased on Gamtoos, which served as a selective host for the new rust culture, designated Pgt-Ug99. Pathogenicity of Pgt-Ug99 was studied in seedling tests of available wheats containing Sr31, as well as other stem rust differential lines. All seedling tests were conducted at least three times in independent inoculations. Isolate Pgt-Ug99 was not virulent to Avocet‘S’/Yr9 (Australian line containing Sr26) or Oom Charl (South African cultivar) but was virulent to the other Sr31 testers: Alondra ‘S’, Bobwhite, Chokka, Clement, Federation/Kavkaz, Gamtoos, Grebe, Kavkaz, Letaba, Line E/Kavkaz, RL6078, and Veery ‘S’. Virulence to Sr31 (infection types [ITs] 3-3 to 3++4) was clearly contrasted by the low reactions (ITs 0; to 1) produced by UVPgt53, a South African pathotype avirulent to Sr31. According to the reactions of the differential lines, Pgt-Ug99 is avirulent to Sr21, -22, -24, -25, -26, -27, -29, -32, -33, -34, -35, -36, -39, -40, -42, and -43, Agi, and Em and virulent to Sr5, -6, -7b, -8a, -8b, -9b, -9e, -9g, -11, -15, -17, -30, -31, and -38. Virulence to the T. ventricosum-derived gene Sr38, which is linked to Lr37 and Yr17 and occurs in cultivars from Australia, the United Kingdom, and the United States, was not known previously (1). Both Pgt-Ug99 and UVPgt53 produced a continuum of ITs (; to 2+3) on Petkus rye (obtained from the USDA-ARS National Small Grains Collection, Aberdeen, ID), the original Sr31 donor source. Pgt-Ug99 did not appear more virulent than UVPgt53 on Petkus. All triticales tested, as well as oat cv. Overberg, were highly resistant to Pgt-Ug99. According to McIntosh et al. (1), Huerta-Espino mentioned a Sr31-virulent culture from Turkey, but this could not be confirmed. Should the Sr31-virulent pathotype migrate out of Uganda, it poses a major threat to wheat production in countries where the leading cultivars have resistance based on this gene. Reference: (1) R. A. McIntosh et al. 1995. Wheat Rusts: An Atlas of Resistance Genes. Kluwer Academic Publishers, Dordrecht, the Netherlands.

scholarly journals Races of Puccinia graminis Identified in the United States During 2003

Plant Disease ◽  
2005 ◽  
Vol 89 (10) ◽  
pp. 1125-1127 ◽  
Author(s):  
Y. Jin
Keyword(s):  
United States ◽  
Resistance Genes ◽  
Stem Rust ◽  
Rust Resistance ◽  
The United States ◽  
Stem Rust Resistance ◽  
Puccinia Graminis ◽  
Wheat Stem Rust ◽  
Stem Rust Resistance Genes ◽  
Rust Resistance Genes

Stem rust of small grain cereals, caused by Puccinia graminis, is a major disease of wheat, barley, and oat. In order to effectively utilize stem rust resistance in the improvement of small grain cereals, it is necessary to monitor the virulence composition and dynamics in the stem rust population. Races of P. graminis from barberry, wheat, barley, and oat were surveyed across the United States during 2003. Aecial infections on barberry were primarily due to P. graminis f. sp. secalis, as inoculations using aeciospores failed to produce infection on wheat and oat. Race QFCS of P. graminis f. sp. tritici was the most common race identified from wheat and barley. Race QFCS has virulence on stem rust resistance genes Sr5, 8a, 9a, 9d, 9g, 10, 17, and 21 that are used for race identification. Race TTTT was identified in 2003. This race possesses virulence to all 16 stem rust resistance genes present in the wheat stem rust differentials and should be targeted in breeding for stem rust resistance. Race QFCN appeared to be a new race in the U.S. stem rust population. Races QCCJ and MCCF were identified, but at low frequencies. Seven races of P. graminis f. sp. avenae were identified from oat, and races NA-27, NA-29, and NA-67 were the predominant races. Race NA-76 was identified for the first time in the United States.

The wheat stem rust (Puccinia graminis f. sp. tritici) population from Washington contains the most virulent isolates reported on barley

Plant Disease ◽  
2021 ◽  
Author(s):  
Arjun Upadhaya ◽  
Sudha GC Upadhaya ◽  
Robert Saxon Brueggeman
Keyword(s):  
Stem Rust ◽  
Virulence Gene ◽  
Single Copy ◽  
The United States ◽  
Sexual Life ◽  
Puccinia Graminis ◽  
Resistance Locus ◽  
Isogenic Line ◽  
Wheat Stem Rust ◽  
Barley Line

A diverse sexual population of wheat stem rust, Puccinia graminis f. sp. tritici (Pgt), exist in the Pacific Northwest (PNW) region of the United States due to the natural presence of Mahonia spp. that serve as alternate hosts to complete its sexual life cycle. The region appears to be a center of stem rust diversity in North America where novel virulence gene combinations can emerge that could overcome deployed barley and wheat stem rust resistances. A total of 100 single pustule isolates derived from stem rust samples collected from barley in Eastern Washington during the 2019 growing season were assayed for virulence on the two known effective barley stem rust resistance genes/loci, Rpg1 and the rpg4/5-mediated resistance locus (RMRL) at the seedling stage. Interestingly, 99% of the Pgt isolates assayed were virulent on barley variety Morex carrying the Rpg1 gene, and 62% of the isolates were virulent on the variety Golden Promise transformant (H228.2c) that carries a single copy insertion of the Rpg1 gene from Morex and is more resistant than Morex to many Rpg1 avirulent isolates. Also, 16% of the isolates were virulent on the near isogenic line HQ-1, that carries the RMRL introgression from the barley line Q21861 in the susceptible Harrington background. Alarmingly, 10% of the isolates were virulent on barley line Q21861 that contains both Rpg1 and RMRL. Thus, we report on the first Pgt isolates worldwide with virulence on both Rpg1 and RMRL when stacked together representing the most virulent Pgt isolates reported on barley.

scholarly journals Races of Puccinia graminis in the United States During 1996

Plant Disease ◽  
1999 ◽  
Vol 83 (9) ◽  
pp. 871-875 ◽  
Author(s):  
D. V. McVey ◽  
D. L. Long ◽  
J. J. Roberts
Keyword(s):  
United States ◽  
Stem Rust ◽  
The United States ◽  
Puccinia Graminis ◽  
Yield Losses ◽  
Wheat Stem Rust ◽  
Soft Red Winter Wheat ◽  
Central Texas ◽  
Wheat Lines ◽  
Red Winter Wheat

Stem rust caused negligible yield losses in 1996 in the United States. Wheat stem rust was first found during the second week of April in a field of soft red winter wheat southwest of Houston, Texas. Race Pgt-TPMK continues to predominate, with 66% of 273 isolates from 100 collections. TPMK represented 76 and 63% of the isolates from wheat in fields and nurseries, respectively. Race QFCS was identified at a frequency of 12 and 29% from farm fields and nurseries, respectively, and 26% overall. Eight other races consisted of 3% or less of the isolates. From barley, race QCCJ, virulent to the Rpg-1 gene for resistance to stem rust, was identified in only 12% of 77 isolates of 27 collections, while TPMK consisted of 64% of the isolates. No virulence was found to wheat lines with genes Sr9b, 13, 22, 24, 25, 26, 27, 29, 30, 31, 32, 37, Gt, or Wld-1. Oat stem rust was first found in late April in southern Louisiana and central Texas. Race NA-27, virulent to Pg-1, -2, -3, -4, and -8, was again the predominant race in the United States, comprising 91% of 93 isolates from 36 collections. NA-5 and NA-16 were the other two races identified, comprising 4% each.

scholarly journals Characterization of Wheat Monogenic Lines with Known Sr Genes and Wheat Lines with Resistance to the Ug99 Race Group for Resistance to Prevalent Races of Puccinia graminis f. sp. tritici in China

Plant Disease ◽  
2020 ◽  
Vol 104 (7) ◽  
pp. 1939-1943
Author(s):  
Xian Xin Wu ◽  
Qiu Jun Lin ◽  
Xin Yu Ni ◽  
Qian Sun ◽  
Rong Zhen Chen ◽  
...  
Keyword(s):  
Food Security ◽  
Stem Rust ◽  
Adult Plant ◽  
Puccinia Graminis ◽  
Wheat Cultivars ◽  
Wheat Stem Rust ◽  
Wheat Improvement ◽  
Wheat Lines ◽  
Sr Genes

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, is one of the most serious fungal diseases in wheat production, seriously threatening the global supply of wheat and endangering food security. The present study was conducted to evaluate wheat monogenic lines with known Sr genes to the most prevalent P. graminis f. sp. tritici races in China. In addition, wheat lines introduced from the International Maize and Wheat improvement Center (CIMMYT) with resistance to the Ug99 race group were also evaluated with the prevalent Chinese P. graminis f. sp. tritici races. The monogenic lines containing Sr9e, Sr21, Sr26, Sr31, Sr33, Sr35, Sr37, Sr38, Sr47, and SrTt3 were effective against races 21C3CTTTM, 34C0MRGSM, and 34C3MTGQM at both seedling and adult-plant stages. In contrast, monogenic lines containing Sr6, Sr7b, Sr8a, Sr9a, Sr9b, Sr9d, Sr9f, Sr9g, Sr13, Sr16, Sr18, Sr19, Sr20, Sr24, Sr28, Sr29, and Sr34 were highly susceptible to these races at both seedling and adult-plant stages. Lines with Sr5, Sr10, Sr13, Sr14, Sr15, Sr17, Sr21, Sr22, Sr23, Sr25, Sr27, Sr29, Sr30, Sr32, Sr36, and Sr39 were resistant to one or more of the tested races. Among the 123 CIMMYT lines, 38 (30.9%) showed varying levels of susceptibility to Chinese P. graminis f. sp. tritici races. The results should be useful for breeding wheat cultivars with resistance to stem rust.

scholarly journals First Report of a New TTKSF Race of Wheat Stem Rust (Puccinia graminis f. sp. tritici) in South Africa and Zimbabwe

Plant Disease ◽  
2012 ◽  
Vol 96 (4) ◽  
pp. 590-590 ◽  
Author(s):  
Z. A. Pretorius ◽  
L. J. Szabo ◽  
W. H. P. Boshoff ◽  
L. Herselman ◽  
B. Visser
Keyword(s):  
South Africa ◽  
South African ◽  
Stem Rust ◽  
Infection Type ◽  
Puccinia Graminis ◽  
Nucleotide Polymorphisms ◽  
Wheat Stem Rust ◽  
Letter Code ◽  
Formed Part ◽  
Sr Gene

Seven races have been described in the Ug99 race group of Puccinia graminis f. sp. tritici (2). Ug99-related races previously recorded in South Africa are TTKSF, TTKSP, and PTKST (4). In December 2010, severe stem rust infection of the winter wheat cv. Matlabas was observed for the first time in South Africa. Race analysis using the 20 North American (NA) stem rust differential lines and letter code system classified the race as TTKSF. In comparative infection studies in a greenhouse, cv. Matlabas seedlings were susceptible (infection type [IT] 4) to isolate UVPgt61/1 (TTKSF+) collected from Afrikaskop in the eastern Free State, whereas the cultivar was resistant (IT 1 to 2) to stem rust isolates 2013 (TTKSF), UVPgt55 (TTKSF), UVPgt59 (TTKSP), and UVPgt60 (PTKST). Isolate 2013 represents the original collection of race TTKSF in South Africa (1). In addition to the NA differentials, no variation in the IT range of seedlings of lines with Sr7a, 8b, 12, 13, 14, 16, 18, 19, 22, 25, 26, 27, 28, 29, 32, 33, 34, 35, 39, 41, 42, 43, 44, Em, R, Tt2, and Satu was observed between UVPgt61/1 and UVPgt55. With the exception of cv. Matlabas, ITs of 106 South African cultivars likewise did not differentiate UVPgt61/1 and UVPgt55. Seedling IT studies were conducted at least twice. Microsatellite analysis (4) showed that all single pustule isolates established from the original Matlabas isolate formed part of the Ug99 group. When characterized with selected single nucleotide polymorphisms (SNPs), all single pustule isolates shared an identical genotype that differed from UVPgt55 (TTKSF), a foreign introduction into South Africa (1,3). SNP genotype analysis suggests that UVPgt61/1 is genetically dissimilar to UVPgt55, as is Zim1009, another TTKSF+ isolate that was collected from Birchenough in Zimbabwe. Studies are underway to determine the identity of the defeated Sr gene in Matlabas and the cultivar has been added to the South African stem rust differential set. TTKSF+ is the eighth race detected in the Ug99 group. Since no other cultivars or advanced lines were found to carry the Matlabas gene, it is unlikely that race TTKSF+ will threaten wheat production in South Africa. However, the occurrence of a new Ug99-related race emphasizes the variability within this internationally important group. References: (1) W. H. P. Boshoff et al. Plant Dis. 86:922, 2002. (2) R. F. Park et al. Euphytica 179:109, 2011. (3) B. Visser et al. Mol. Plant Pathol. 10:213, 2009. (4) B. Visser et al. Euphytica 179:119, 2011.

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