scholarly journals Resistance of Aegilops Species from Israel to Widely Virulent African and Israeli Races of the Wheat Stem Rust Pathogen

Plant Disease ◽  
2014 ◽  
Vol 98 (10) ◽  
pp. 1309-1320 ◽  
Author(s):  
Jeness C. Scott ◽  
Jacob Manisterski ◽  
Hanan Sela ◽  
Pnina Ben-Yehuda ◽  
Brian J. Steffenson
Keyword(s):  
Stem Rust ◽  
High Frequency ◽  
Infection Type ◽  
Low Frequency ◽  
Puccinia Graminis ◽  
Aegilops Species ◽  
Wheat Stem Rust ◽  
Transfer Resistance ◽  
Desert Region ◽  
Rust Pathogen

Widely virulent races of the stem rust pathogen (Puccinia graminis f. sp. tritici) such as those isolated from Africa (e.g., TTKSK, isolate synonym Ug99) threaten wheat production worldwide. To identify Aegilops accessions with effective resistance to such virulent stem rust races, up to 10 different species from Israel were evaluated against African races TTKSK, TTKST, and TTTSK and the Israeli race TTTTC as seedlings in the greenhouse. A wide diversity of stem rust reactions was observed across the Aegilops spp. and ranged from highly resistant (i.e., infection type 0) to highly susceptible (infection type 4). The frequency of resistance within a species to races TTTTC and TTKSK ranged from 7 and 14%, respectively, in Aegilops searsii to 98 and 100% in AE. speltoides. In all, 346 accessions were found resistant to the three African races and 138 accessions were resistant (or heterogeneous with a resistant component) to all four races. The species with broadly resistant accessions included Ae. longissima (59 accessions), Ae. peregrina (47 accessions), Ae. sharonensis (15 accessions), Ae. geniculata (9 accessions), Ae. kotschyi (5 accessions), and Ae. bicornis (3 accessions). Few geographical trends or correlations with climatic variables were observed with respect to stem rust resistance in the Aegilops spp. The exception was Ae. longissima infected with race TTTTC, where a high frequency of resistance was found in central and northern Israel and a very low frequency in southern Israel (Negev desert region). This geographical trend followed a pattern of annual precipitation in Israel, and a significant correlation was found between this variable and resistance in Ae. longissima. Although difficult, it is feasible to transfer resistance genes from Aegilops spp. into wheat through conventional wide-crossing schemes or, alternatively, a cloning and transformation approach. The broadly resistant accessions identified in this study will be valuable in these research programs.

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.

scholarly journals Emergence of the Ug99 lineage of the wheat stem rust pathogen through somatic hybridisation

2019 ◽  
Author(s):  
Feng Li ◽  
Narayana M. Upadhyaya ◽  
Jana Sperschneider ◽  
Oadi Matny ◽  
Hoa Nguyen-Phuc ◽  
...  
Keyword(s):  
Stem Rust ◽  
Puccinia Graminis ◽  
Wheat Stem Rust ◽  
Haploid Nucleus ◽  
Somatic Hybridisation ◽  
Global Food Security ◽  
Proximity Analysis ◽  
Rust Pathogen ◽  
Nuclear Exchange ◽  
Global Food

AbstractParasexuality contributes to diversity and adaptive evolution of haploid (monokaryotic) fungi. However non-sexual genetic exchange mechanisms are not defined in dikaryotic fungi (containing two distinct haploid nuclei). Newly emerged strains of the wheat stem rust pathogen, Puccinia graminis f. sp. tritici (Pgt), such as Ug99, are a major threat to global food security. Here we show that Ug99 arose by somatic hybridisation and nuclear exchange between dikaryons. Fully haplotype-resolved genome assembly and DNA proximity analysis revealed that Ug99 shares one haploid nucleus genotype with a much older African lineage of Pgt, with no recombination or reassortment. Generation of genetic variation by nuclear exchange may favour the evolution of dikaryotism by providing an advantage over diploidy.

scholarly journals Pathogenic Variability of Wheat Stem Rust Pathogen (Puccinia graminis f. sp. tritici) in Hararghe Highlands, Ethiopia

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Arif Abrahim ◽  
Temam Hussein ◽  
Ayele Badebo
Keyword(s):  
Resistance Genes ◽  
Stem Rust ◽  
Agricultural Research ◽  
Low Frequency ◽  
Puccinia Graminis ◽  
Total Production ◽  
Rust Disease ◽  
Wheat Stem Rust ◽  
Pathogenic Variability ◽  
Infection Types

Wheat is one of the important major crops of Hararghe Highlands. It is third in land coverage and total production after sorghum and maize. However, the wheat stem rust disease is threatening production of wheat in this region. So, this research was conducted with the following objective: to determine the population of Puccinia graminis f. sp. tritici in Hararghe Highlands. A total of 200 fields were surveyed and stem rust samples were collected and transported to Kulumsa Agricultural Research Center for race analysis. Inoculation of differentials carrying resistance genes Sr24 and Sr-Tmp indicated typical low infection types on all isolates. Isolates EH5, EH8, and EH3 from East Hararghe and WH2, WH1, and WH3 from West Hararghe showed high virulence of infection in all differential lines. Ten (10) races were identified by using Puccinia graminis tritici code system: TTGSK, PTJQK, TTSSK, TTKSK, TRSSK, and TTJQK from East Hararghe and TTTSK and TTSQK from West Hararghe zones. Race TTSSK was most frequent (25%) followed by TTKSK (25%) in East Hararghe. Race TTSSK showed 50% frequency of occurrence in West Hararghe zones. The low frequency of occurrences indicated high variability of the races in the survey areas. Therefore, monitoring of populations of pathogens is important for the national and regional research centers. Detection of pathogen virulence evolution and of currently effective resistance genes is necessary and must be applied within a system of resistance gene management.

scholarly journals Isozyme Studies on the Origin and Evolution of Puccinia Graminis F. SP. Tritici in Australia

1982 ◽  
Vol 35 (2) ◽  
pp. 231 ◽  
Author(s):  
JJ Burdon ◽  
DR Marshall ◽  
NH Luig ◽  
DJS Gow
Keyword(s):  
Stem Rust ◽  
Major Change ◽  
Puccinia Graminis ◽  
Flora Of Australia ◽  
Wheat Stem Rust ◽  
Origin And Evolution ◽  
Enzyme Systems ◽  
Rust Pathogen

Isozyme phenotypes for eight enzyme systems were used to assess the origins and evolution of P. graminis f. sp. tritici (the wheat stem rust pathogen) in Australia. The results obtained by this approach agreed with pathways postulated on the basis of virulence studies, confirming the suggestion that most of the major changes in the wheat stem rust pathogen flora of Australia have resulted from overseas introductions. Moreover, they suggest that, although the more recent of these were from Africa, the first major change detected occurred as a result of an introduction from elsewhere.

scholarly journals Characteristics of the virulence of the wheat stem rust pathogen in the conditions of the Saratov region

2021 ◽  
pp. 23-27
Author(s):  
Elmira Aleksandrovna Konkova
Keyword(s):  
Bread Wheat ◽  
Stem Rust ◽  
Significant Variation ◽  
The Other ◽  
Puccinia Graminis ◽  
Wheat Stem Rust ◽  
Saratov Region ◽  
Rust Pathogen ◽  
Highly Virulent ◽  
Biotrophic Fungus

Stem rust (pathogen - biotrophic fungus Puccinia graminis f. sp. tritici Erikss. & Henning) – a particularly deleterious disease of bread wheat. In this article the results of the analysis of the structure of samples of Saratov populations of wheat stem rust pathogen by signs of virulence during 2016-2020 were presented. A total of 60 pathogen isolates were characterized for virulence. In general, Saratov P. graminis populations were characterized as highly virulent during the study period. The significant variation in the virulence frequencies of P. graminis was observed in lines with the genes Sr9b, Sr9g, Sr12, Sr21, Sr25, Sr27, Sr30, Sr32, Sr33, Sr7a+12, Sr17+13. The other Sr lines used in the analysis, the virulence rates remained consistently high in all the years of research. Genes and combinations of genes: SrSatu, Sr24, Sr25+9g, Sr25+31, Sr25+38 were shown to be effective to P. graminis populations in 2016-2020.

scholarly journals Resistance to Puccinia graminis f. sp. avenae in Barley Is Associated with the Rpg5 Locus

2015 ◽  
Vol 105 (4) ◽  
pp. 490-494 ◽  
Author(s):  
Peter Dracatos ◽  
Davinder Singh ◽  
Tom Fetch ◽  
Robert Park
Keyword(s):  
Stem Rust ◽  
Recombinant Inbred ◽  
Puccinia Graminis ◽  
Wheat Stem Rust ◽  
Formae Speciales ◽  
Major Threat ◽  
Resistant Lines ◽  
Rust Pathogen ◽  
Ril Population ◽  
Parental Lines

In barley, gene Rpg5 was first identified for providing resistance to the rye stem rust pathogen (Puccinia graminis f. sp. secalis). A subsequent study determined that Rpg5 is required for rpg4-mediated resistance to the wheat stem rust pathogen (P. graminis f. sp. tritici) including pathotype TTKSK (“Ug99”), which poses a major threat to global wheat and barley production. Based on the effectiveness of Rpg5 against P. graminis f. sp. tritici and P. graminis f. sp. secalis, we assessed whether it also conferred resistance to the oat stem rust pathogen (P. graminis f. sp. avenae). A barley F8 recombinant inbred line (RIL) population was produced by crossing ‘Q21861’ (Rpg1 and Rpg5) with ‘73-G1’ (Rpg1), which is susceptible to P. graminis f. sp. avenae, P. graminis f. sp. secalis, and some pathotypes of P. graminis f. sp. tritici. Seedling tests were performed on the F8 RIL population using Australian pathotypes of P. graminis f. sp. tritici, P. graminis f. sp. secalis, P. graminis f. sp. avenae, and a putative somatic hybrid between P. graminis f. sp. tritici and P. graminis f. sp. secalis known as the ‘Scabrum’ rust. Segregation in the responses to all rust isolates for the RILs was identical (50 resistant: 52 susceptible), and fitted a 1:1 ratio (X2 = 0.039, P = 0.843), indicating that resistance to all isolates was monogenetically inherited. Screening of the RILs and the parental lines with perfect markers for the functional Rpg1 and Rpg5 resistance alleles indicated that Rpg1 was fixed, while Rpg5 was positive in all resistant lines and negative in all susceptible lines. This suggests that different formae speciales of P. graminis may share common effectors, and that the Rpg5 locus confers resistance to both P. graminis f. sp. tritici and P. graminis f. sp. secalis and the heterologous formae speciales of P. graminis, P. graminis f. sp. avenae.

scholarly journals First Report of Races TKTTP and TKKTP of Puccinia graminis f. sp. tritici with Virulence to Wheat Stem Rust Resistance Gene Sr24 in Turkey and Tunisia

Plant Disease ◽  
2021 ◽  
Author(s):  
Kumarse Nazari ◽  
Ezgi Kurtulus ◽  
Handan Kavaz ◽  
Omer M. Ozturk ◽  
Yesim Egerci ◽  
...  
Keyword(s):  
Resistance Gene ◽  
Stem Rust ◽  
Rust Resistance ◽  
Infection Type ◽  
Single Gene ◽  
Stem Rust Resistance ◽  
Puccinia Graminis ◽  
Wheat Cultivars ◽  
Wheat Stem Rust ◽  
First Report

Severe wheat stem rust caused by Puccinia graminis Pers.:Pers. f. sp. tritici Erikss. (Pgt) can result in complete crop failure. In recent years, the increasing frequency and the early onset of stem rust in Central West Asia and North Africa (CWANA) has become a big concern. The Sr24 resistance gene, one of the most effective stem rust resistance genes effective against most P. graminis f. sp. tritici races worldwide, has been widely deployed. Until the recent establishment of virulence to Sr24 within the Ug99 lineage of the pathogen in Africa (Hei et al. 2020; Jin et al. 2008; Patpour et al. 2015), Iraq (Nazari et al., 2021), occasional detections of races virulent to Sr24 were reported in South Africa (Le Roux and Rijkenberg 1987), India (Bhardwaj et al. 1990), Germany (Olivera Firpo et al. 2017), Georgia (Olivera, et al. 2019), and Western Siberia (Skolotneva et al., 2020). During the rust surveys conducted in Sinops, Samsun, and Kastomonu in the Black Sea region in northern Turkey in 2018, 19 isolates were collected. Single pustule (SP) isolates were developed and used in race analysis in the Biosafety Rust Laboratory, Regional Cereal Rust Research Center (RCRRC), Izmir, Turkey. Sample recovery, experimental procedures for pre-inoculation, inoculation, incubation, and race typing were conducted as previously described (Nazari et al. 2021). Among the tested SP isolates, two isolates showed a high infection type (IT) of 33+ on the Sr24 tester line (Little Club/Agent) and a low infection type of 11+ for the source of Sr31 (Benno/6*LMPG-6). Eight SP isolates were further developed from the high IT 33+ pustules collected from the Sr24 tester line. After spore multiplications, they were used in inoculation of the 20 North American stem rust single-gene lines used to differentiate races of P. graminis f. sp. tritici, plus Trident (Sr38+), Siouxland (Sr24+Sr31), and Sisson (Sr31+Sr36). Five SP-derived isolates with IT 33+ on the Sr24 single-gene line collected from Samsun (Alacam – Etyemez; Location: N 41.61889 E 35.55722) and Sinop (Merkez-Sanlıoglu; Location: N 41.85556 E 35.04889) were identified as race TKKTP and the remaining three SP isolates as race TKTTP. In 2020, we detected two isolates of TKKTP among the stem rust samples from Tunisia submitted to RCRRC. These two isolates were collected from bread wheat cultivars Heydna and Tahmet at a trial site near Bou Salem in Western Tunisia (Location: N 36.5351 E 8.95486). Based on the negative results of the Stage 1 test using a suite of four real-time polymerase chain reaction assays diagnostic for the Ug99 race group developed by Szabo (2012), these two races should not belong to the Ug99 race group when compared to the reference Ug99 race TTKTT from Kenya. These races were virulent to Sr5, Sr21, Sr9e, Sr7b, Sr6, Sr8a, Sr9g, Sr9b, Sr30, Sr17, Sr9a, Sr9d, Sr10, SrTmp, Sr24, Sr38, and SrMcN. In addition to these genes, race TKTTP was virulent to Sr36. Both races were avirulent to Sr11 and Sr31. To our knowledge, this is the first report of P. graminis f. sp. tritici races with the Sr24 virulence in Turkey and Tunisia. The results reflect an increasing trend of virulence to Sr24 in the pathogen populations, and raise a great concern given the deployment of the Sr24 resistance gene in widely grown wheat cultivars worldwide.

scholarly journals Isozyme Uniformity and Virulence Variation in Puccinia graminis f. sp. tritici and P. recondita f. sp. tritici in Australia

1983 ◽  
Vol 36 (4) ◽  
pp. 403 ◽  
Author(s):  
JJ Burdon ◽  
NH Luig ◽  
DR Marshall
Keyword(s):  
Leaf Rust ◽  
Stem Rust ◽  
Growing Season ◽  
Puccinia Graminis ◽  
Wheat Leaf Rust ◽  
Wheat Stem Rust ◽  
Rust Pathogen ◽  
Wheat Leaf ◽  
Virulence Variation

During a routine survey of pathotypes of Puccinia graminis f. sp. tritici (the wheat stem rust pathogen) and P. recondita f. sp. tritici (the wheat leaf rust pathogen) present in Australia during the 1981-82 growing season, 16 pathotypes of P. graminis tritici and 12 pathotypes of P. recondita tritici were detected in total samples of 193 and 180 isolates of the two pathogens respectively. For both pathogens the distribution of isolates amongst the different pathotypes was highly uneven. The commonest pathotype of P. graminis tritici (pathotype 343-1,2,3,5,6) comprised 50% of isolates while the commonest pathotype of P. recondita tritici (pathotype 104-2,3,6) made up 69 % of isolates. Many pathotypes of both species were represented by single isolates only.

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