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

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Feng Li ◽  
Narayana M. Upadhyaya ◽  
Jana Sperschneider ◽  
Oadi Matny ◽  
Hoa Nguyen-Phuc ◽  
...  
Keyword(s):  
Stem Rust ◽  
Wheat Stem Rust ◽  
Haploid Nucleus ◽  
Somatic Hybridisation ◽  
Global Food Security ◽  
Proximity Analysis ◽  
Rust Pathogen ◽  
Fungal Populations ◽  
Nuclear Exchange ◽  
Global Food

Abstract Parasexuality 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 provide genomics-based evidence supporting that Ug99 arose by somatic hybridisation and nuclear exchange between dikaryons. Fully haplotype-resolved genome assembly and DNA proximity analysis reveal that Ug99 shares one haploid nucleus genotype with a much older African lineage of Pgt, with no recombination or chromosome reassortment. These findings indicate that nuclear exchange between dikaryotes can generate genetic diversity and facilitate the emergence of new lineages in asexual fungal populations.

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 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 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.

Retrospective analysis of virulence of the North Caucasian population of wheat stem rust pathogen

2019 ◽  
Vol 1 (81) ◽  
pp. 85-90
Author(s):  
Galina Volkova ◽  
◽  
Olesya Miroshnichenko ◽  
Olga Tarancheva ◽  
◽  
...  
Keyword(s):  
Retrospective Analysis ◽  
Stem Rust ◽  
Caucasian Population ◽  
Wheat Stem Rust ◽  
The North ◽  
Rust Pathogen
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