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.

Metabolism of alicyclic acids and phenylpropanoids by uredospores of wheat stem rust and wheat leaf rust

1970 ◽  
Vol 48 (6) ◽  
pp. 1085-1091
Author(s):  
A. O. Jackson ◽  
D. J. Samborski ◽  
R. Rohringer
Keyword(s):  
Leaf Rust ◽  
Phenolic Acids ◽  
Stem Rust ◽  
Phenylalanine Ammonia Lyase ◽  
Wheat Leaf Rust ◽  
Shikimate Dehydrogenase ◽  
Wheat Stem Rust ◽  
Germination Medium ◽  
Tyrosine Ammonia Lyase ◽  
Wheat Leaf

Uredospores of wheat leaf rust did not take up or metabolize exogenous supplies of quinate-U-14C, shikimate-U-14C, p-coumarate-α-14C, or ferulate-α-14C. Caffeate-α-14C was converted to an unidentified ether-insoluble component which was recovered from the germination medium.Phenylalanine-U-14C and tyrosine-U-14C were readily taken up by uredospores of both rusts and were recovered from the solvent-soluble and insoluble fractions. No evidence for phenylalanine/tyrosine interconversion was obtained. Radioactivity was not incorporated into glycosides or free and bound esters of phenolic acids when phenylalanine-U-14C or tyrosine-U-14C were used as precursors. Radioactivity was not detected in free phenolic acids when uredospores were fed phenylalanine-U-14C. When tyrosine-U-14C was the precursor, radioactive p-coumarate was detected in the germination medium kept at 20 °C, and radioactive p-coumarate and caffeate were both recovered from the germination medium kept at 30 °C.Extracts of uredospores of wheat stem rust and wheat leaf rust contained shikimate dehydrogenase and tyrosine ammonia-lyase. Quinate dehydrogenase and phenylalanine ammonia-lyase were not detected.

PARATHION, A SELECTIVE RUST FUNGICIDE, COMPARED WITH MANEB IN THE CONTROL OF CEREAL RUSTS

1968 ◽  
Vol 48 (3) ◽  
pp. 261-265
Author(s):  
G. Fleischmann ◽  
J. W. Martens ◽  
R. I. H. McKenzie
Keyword(s):  
Stem Rust ◽  
Field Tests ◽  
Crown Rust ◽  
Wheat Leaf Rust ◽  
Wheat Stem Rust ◽  
Oat Crown Rust ◽  
Wheat Leaf ◽  
Excellent Control ◽  
Significant Yield ◽  
Cereal Rusts

Parathion, an organophosphorus insecticide, controlled oat crown rust, Puccinia coronata Corda f. sp. avenae Erikss., in the greenhouse at a concentration of 0.32 g/liter when applied to oats before inoculation with rust urediospores. Slight reductions in the amount of oat stem rust, P. graminis Pers. f. sp. avenae Erikss. and Henn., wheat stem rust, P. graminis Pers. f. sp. tritici Erikss. and Henn., and wheat leaf rust, P. recondita Rob. ex. Desm., were achieved at higher concentrations. In field tests, three applications of parathion gave excellent control of oat crown rust. Late infections of oat stem rust, which caused significant yield reductions, were unaffected by parathion, but were effectively controlled by maneb.

scholarly journals Dissecting the first phased dikaryotic genomes of the wheat rust pathogen Puccinia triticina reveals the mechanisms of somatic exchange in nature

2019 ◽  
Author(s):  
Jing Qin Wu ◽  
Chongmei Dong ◽  
Long Song ◽  
Christina A. Cuomo ◽  
Robert F. Park
Keyword(s):  
Leaf Rust ◽  
Somatic Hybridization ◽  
Puccinia Triticina ◽  
Genomic Variation ◽  
Hybrid Wheat ◽  
Wheat Cultivars ◽  
Wheat Leaf Rust ◽  
Virulence Evolution ◽  
Rust Pathogen ◽  
Wheat Leaf

AbstractAlthough somatic hybridization (SH) has been proposed as a means of accelerating rust pathogen virulence evolution in the absence of sexual recombination, previous studies are limited to the laboratory and none have revealed how this process happens. Using long-read sequencing, we generated dikaryotic phased genomes and annotations for three Australian field-collected isolates of the wheat leaf rust pathogen (Puccinia triticina; Pt), including a putative asexual hybrid (Pt64) and two putative parental isolates (Pt104 and Pt53; 132-141 Mb,155-176 contigs, N50 of 1.9-2.1 Mb). The genetic dissection based on the high-quality phased genomes including whole-genome alignments, phylogenetic and syntenic analyses along with short-read sequencing of 27 additional Pt isolates convergently demonstrated that Pt64, which rendered several commercial hybrid wheat cultivars susceptible to leaf rust, arose from SH between isolates within the Pt53 and Pt104 lineages. Parentage analysis demonstrated the role of mitotic crossover in the derivation of both nuclei of Pt64. Within HD mating type genes, the distinct specificity regions in Pt64 and the distinct phylogenetic pattern of the remaining admixed isolates suggested high genetic variation in specificity-related regions on the b locus intrinsically associated with the SH. This study not only provided a fundamental platform for investigating genomic variation underlying virulence evolution in one of the most devastating wheat pathogens, but also offered an in-depth understanding of the mechanisms of naturally occurring SH. This asexual mechanism can be broadly exploited by any dikaryotic pathogen to accelerate virulence evolution, and understanding this process is both urgent and crucial for sustainable pathogen control.ImportanceStrategies to manage plant rust pathogens are challenged by the constant emergence of new virulence. Although somatic hybridization has been proposed as a means by which rusts could overcome host resistance rapidly and cause crop loss, there is very little evidence of this process in nature and the mechanisms underlying it are not known. This study generated and analysed the first dikaryotic phased genomes of the wheat leaf rust pathogen, identifying an isolate as a hybrid and for the first time unveiling parasexuality via mitotic crossover in a rust pathogen. The erosion of the resistance of several hybrid wheat cultivars in agriculture by the hybrid rust has important implications for breeding efforts targeting durable resistance and sustained rust control.

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 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.

Inheritance of leaf rust and stem rust resistance in 'Roblin' wheat

Genome ◽  
1993 ◽  
Vol 36 (2) ◽  
pp. 289-293 ◽  
Author(s):  
P. L. Dyck
Keyword(s):  
Triticum Aestivum ◽  
Leaf Rust ◽  
Stem Rust ◽  
Rust Resistance ◽  
Leaf Rust Resistance ◽  
Triticum Aestivum L ◽  
Stem Rust Resistance ◽  
Puccinia Graminis ◽  
Susceptible Cultivar ◽  
Wheat Leaf

The Canadian common wheat (Triticum aestivum L.) cultivar 'Roblin' is resistant to both leaf rust (Puccinia recondita Rob. ex. Desm.) and stem rust (Puccinia graminis Pers. f. sp. tritici Eriks. and E. Henn.). To study the genetics of this resistance, 'Roblin' was crossed with 'Thatcher', a leaf rust susceptible cultivar, and RL6071, a stem rust susceptible line. A set of F6 random lines was developed from each cross. The random lines and the parents were grown in a field rust nursery artificially inoculated with a mixture of P. recondita and P. graminis isolates and scored for rust reaction. The same material was tested with specific races of leaf rust and stem rust. These data indicated that 'Roblin' has Lr1, Lr10, Lr13, and Lr34 for resistance to P. recondita and Sr5, Sr9b, Sr11, and possibly Sr7a and Sr12 for resistance to P. graminis. In a 'Thatcher' background, the presence of Lr34 contributes to improve stem rust resistance, which appears also to occur in 'Roblin'.Key words: Triticum aestivum, wheat, leaf rust resistance, stem rust resistance.

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.

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