Distribution of virulence in two populations of Puccinia coronata f.sp. avenae in Canada

1993 ◽  
Vol 71 (7) ◽  
pp. 946-950 ◽  
Author(s):  
J. A. Kolmer ◽  
J. Chong
Keyword(s):  
Single Gene ◽  
Crown Rust ◽  
Puccinia Coronata ◽  
Differential Host ◽  
Eastern Population ◽  
Oat Crown Rust ◽  
Virulence Phenotype ◽  
Sexual Recombination ◽  
Two Populations ◽  
Specific Virulence

The distributions of virulence in the eastern (Ontario and Quebec) and prairie (Manitoba and Saskatchewan) populations of Puccinia coronata f.sp. avenae in Canada were examined from virulence survey data in 1974 and 1990 to determine if these populations resemble previously characterized sexual or asexual cereal rust populations. Single uredinial isolates from both populations were evaluated for virulence phenotype on single gene differential host lines. The eastern and prairie populations in 1974 were dominated by relatively simple phenotypes that were avirulent or virulent to one of the single gene lines. In 1990, after virulence to crown rust resistance genes Pc39 and Pc38/Pc39 increased in frequency in the eastern and prairie populations, respectively, the eastern population had an increased proportion of isolates with virulences to one to two genes, and the prairie population was dominated by isolates with one to four virulences. Increasing virulence to Pc39 in the eastern population and Pc38 and Pc39 in the prairie population also contributed to a greater number of phenotypes in both populations in 1990 compared with 1974. The distributions of virulence differences among isolates in both populations in 1974 and 1990 appeared to be nearly random, approximating Poisson distributions. Associations between pairs of specific virulences to 10 single gene lines were examined in both populations during 1974 – 1990. Relatively few pairs of virulences in both populations were found to be nonrandomly associated. No associations between pairs of virulences persisted for more than 3 years in either population. Sexual recombination most likely functions in evenly distributing virulences among phenotypes in both populations. Key words: oat, oat crown rust, sexual reproduction, specific virulence.

Assessment of virulence patterns in crown rust populations

1968 ◽  
Vol 46 (5) ◽  
pp. 613-617 ◽  
Author(s):  
George Fleischmann
Keyword(s):  
Crown Rust ◽  
Puccinia Coronata ◽  
Western Canada ◽  
Differential Host ◽  
Oat Crown Rust ◽  
Virulence Pattern ◽  
Continued Use ◽  
Race Identification

Two methods of determining the virulence pattern of oat crown rust, Puccinia coronata f. sp. avenae, populations collected in 1965, 1966, and 1967, in Eastern and Western Canada were compared. The results with a single-pustule isolate from each of 50 field collections were as accurate as those obtained with two single-pustule isolates from 100 or more field collections. The continued use of Bond and Ukraine as differential host varieties is of little value except for purposes of race identification, because they are attacked by most of the isolates.

Virulence dynamics and phenotypic diversity of Puccinia coronata f.sp. avenae in Canada from 1974 to 1990

1993 ◽  
Vol 71 (2) ◽  
pp. 248-255 ◽  
Author(s):  
J. Chong ◽  
J. A. Kolmer
Keyword(s):  
Rust Resistance ◽  
Phenotypic Diversity ◽  
Puccinia Coronata ◽  
Eastern Region ◽  
Eastern Population ◽  
Virulence Phenotype ◽  
Oat Cultivars ◽  
Almost All ◽  
Two Populations ◽  
Rust Resistance Genes

The changes in virulence phenotype frequencies of Puccinia coronata Cda. f.sp. avenae Eriks. since 1974 in the eastern (Ontario, Quebec, and the Maritimes) and prairie (Manitoba and Saskatchewan) regions of Canada were examined. In the eastern region, frequency of virulence to Pc39 increased after the release of a cultivar with this resistance gene. Virulence to Pc38 and Pc39 increased in the prairie region after cultivars with these two genes were released. The frequencies of virulence to Pc35 and Pc56 fluctuated between 9 and 53% in the eastern region, even though these genes are not known to be present in oat cultivars grown there. In the prairie region, the frequencies of virulence to Pc35 and Pc40 fluctuated between 21 and 60% from 1974 to 1990, and virulence to Pc46 increased from 7% in 1974 to 72% in 1985, even though these genes have not been used in commercial oat cultivars. The prairie population generally had higher levels of phenotypic diversity, as measured by the Shannon, Simpson, and Gleason indexes, than did the eastern population in almost all years examined. These results contrast with previous studies using an older set of differentials in which the eastern population had a higher level of phenotypic diversity than the prairie population. The Rogers index indicated that differences in frequencies of virulence phenotypes between the two populations has increased gradually since 1974. Key words: crown rust, resistance genes, selection, phenotypic diversity.

scholarly journals Virulence of Oat Crown Rust in Brazil and Uruguay

Plant Disease ◽  
2005 ◽  
Vol 89 (8) ◽  
pp. 802-808 ◽  
Author(s):  
K. J. Leonard ◽  
J. A. Martinelli
Keyword(s):  
Avena Sativa ◽  
Western Siberia ◽  
Specific Resistance ◽  
The United States ◽  
Crown Rust ◽  
Puccinia Coronata ◽  
South American ◽  
Oat Crown Rust ◽  
High Virulence ◽  
Important Disease

Race-specific resistance to crown rust, the most important disease of oat (Avena sativa) in Bra-zil, often fails within a few years of use in Brazilian cultivars. Virulence of 144 isolates of Puccinia coronata from cultivated oat in Brazil in 1997 to 1999 and 36 isolates from Uruguay in 1994-95 and 1998 was tested on a set of 27 oat crown rust differentials lines, each with a different Pc gene for race-specific resistance. Frequencies of virulence and mean virulence complexity were compared among these five collections from Brazil and Uruguay as well as with mean virulence complexity for a collection of 17 isolates from cultivated oat in western Siberia in Russia. Virulence-avirulence for each of the 27 Pc genes was polymorphic in both Brazil and Uruguay. Virulence frequencies were similar for collections from Brazil in 1998 and 1999 and for the collection from Uruguay from 1998, but there were large differences between the 1997 collection and the 1998 and 1999 collections from Brazil. Mean virulence complexity in both Brazil and Uruguay was greater than reported in the United States and much greater than in the Russian collection of P. coronata. A large number of races of P. coronata were found, with no more than five isolates of any race found in a single year in Brazil or Uruguay. The high virulence complexity and great diversity of virulence polymorphisms in Brazil and Uruguay make it unlikely that race-specific resistance can be effective there even though the South American populations of P. coronata are apparently entirely asexual.

scholarly journals De Novo Assembly and Phasing of Dikaryotic Genomes from Two Isolates of Puccinia coronata f. sp. avenae, the Causal Agent of Oat Crown Rust

mBio ◽  
2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Marisa E. Miller ◽  
Ying Zhang ◽  
Vahid Omidvar ◽  
Jana Sperschneider ◽  
Benjamin Schwessinger ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
De Novo ◽  
Rust Fungus ◽  
Expression Patterns ◽  
Haplotype Diversity ◽  
Crown Rust ◽  
Puccinia Coronata ◽  
Small Subset ◽  
Nucleotide Polymorphisms ◽  
Oat Crown Rust

ABSTRACT Oat crown rust, caused by the fungus Pucinnia coronata f. sp. avenae, is a devastating disease that impacts worldwide oat production. For much of its life cycle, P. coronata f. sp. avenae is dikaryotic, with two separate haploid nuclei that may vary in virulence genotype, highlighting the importance of understanding haplotype diversity in this species. We generated highly contiguous de novo genome assemblies of two P. coronata f. sp. avenae isolates, 12SD80 and 12NC29, from long-read sequences. In total, we assembled 603 primary contigs for 12SD80, for a total assembly length of 99.16 Mbp, and 777 primary contigs for 12NC29, for a total length of 105.25 Mbp; approximately 52% of each genome was assembled into alternate haplotypes. This revealed structural variation between haplotypes in each isolate equivalent to more than 2% of the genome size, in addition to about 260,000 and 380,000 heterozygous single-nucleotide polymorphisms in 12SD80 and 12NC29, respectively. Transcript-based annotation identified 26,796 and 28,801 coding sequences for isolates 12SD80 and 12NC29, respectively, including about 7,000 allele pairs in haplotype-phased regions. Furthermore, expression profiling revealed clusters of coexpressed secreted effector candidates, and the majority of orthologous effectors between isolates showed conservation of expression patterns. However, a small subset of orthologs showed divergence in expression, which may contribute to differences in virulence between 12SD80 and 12NC29. This study provides the first haplotype-phased reference genome for a dikaryotic rust fungus as a foundation for future studies into virulence mechanisms in P. coronata f. sp. avenae. IMPORTANCE Disease management strategies for oat crown rust are challenged by the rapid evolution of Puccinia coronata f. sp. avenae, which renders resistance genes in oat varieties ineffective. Despite the economic importance of understanding P. coronata f. sp. avenae, resources to study the molecular mechanisms underpinning pathogenicity and the emergence of new virulence traits are lacking. Such limitations are partly due to the obligate biotrophic lifestyle of P. coronata f. sp. avenae as well as the dikaryotic nature of the genome, features that are also shared with other important rust pathogens. This study reports the first release of a haplotype-phased genome assembly for a dikaryotic fungal species and demonstrates the amenability of using emerging technologies to investigate genetic diversity in populations of P. coronata f. sp. avenae.

scholarly journals Crown rust pathotypes determined on oats in the Czech Republic from 2004 to 2006 and reaction to oat cultivars

2008 ◽  
Vol 44 (No. 2) ◽  
pp. 60-65 ◽  
Author(s):  
H. Jiráková ◽  
A. Hanzalová
Keyword(s):  
Czech Republic ◽  
Resistance Genes ◽  
Virulence Genes ◽  
Resistance Breeding ◽  
Crown Rust ◽  
Puccinia Coronata ◽  
The Czech Republic ◽  
Oat Crown Rust ◽  
Oat Cultivars ◽  
High Diversity

The incidence of oat crown rust (Puccinia coronata var. avenae Fraser et Ledingham) pathotypes was recorded in the Czech Republic in 2004–2006. The virulence of collected 79 monopustule oat crown rust isolates was assessed on 23 differentials. High diversity was observed; the isolates possessed from 0 to 8 virulence genes. More than 80% of pathotypes were recorded only once. Pathotypes BLBG and BLBC were the most frequent. None of the tested isolates was virulent to resistance genes Pc39, Pc50, Pc52, Pc59, Pc62 and Pc68. Registered cultivars Avenuda, Dalimil, Auron, Isak were susceptible to the majority of pathotypes, cvs. Abel, Ardo, Atego, Azur, Neklan, Radius and Saul to all used pathotypes. Only the Czech cultivar Vok was resistant to all but four used pathotypes. Acquired data are useful for resistance breeding.

THE DISTRIBUTION AND FREQUENCY OF OCCURRENCE OF PHYSIOLOGIC RACES OF PUCCINIA CORONATA CORDA F. SP. AVENAE ERIKSS., IN CANADA, 1952 TO 1961

1963 ◽  
Vol 41 (4) ◽  
pp. 481-487 ◽  
Author(s):  
G. Fleischmann ◽  
D. J. Samborski ◽  
B. Peturson
Keyword(s):  
Crown Rust ◽  
Puccinia Coronata ◽  
Western Canada ◽  
Frequency Of Occurrence ◽  
Rhamnus Cathartica ◽  
Alternate Host ◽  
Eastern Canada ◽  
The West ◽  
Differential Host ◽  
Physiologic Races

From 1952 to 1956 the races of crown rust, Puccinia coronata Corda f. sp. avenae Erikss., that predominated in Eastern Canada were 201, 202, 203, 209, 239, and 240. Races 201, 202, and 204 occurred most frequently in Western Canada. These races cannot attack the differential host variety Victoria, from which the currently grown commercial varieties Rodney and Garry derive their resistance. Garry and Rodney became widely grown in Canada by 1957, and since then races 216 and 274, which can attack Victoria, have become prominent, especially in Western Canada.More races are found in Eastern Canada than in the west, and there is less tendency for a few races to predominate in the east. These differences may be explained by the relatively frequent occurrence of the alternate host, Rhamnus cathartica L., in important oat-growing regions of Eastern Canada, and by the cultivation of large acreages of a few varieties with similar resistance in the west. The most important factor affecting the distribution and frequency of occurrence of races is the variety grown.

scholarly journals De novo assembly and phasing of dikaryotic genomes from two isolates of Puccinia coronata f. sp. avenae, the causal agent of oat crown rust

2017 ◽  
Author(s):  
Marisa E. Miller ◽  
Ying Zhang ◽  
Vahid Omidvar ◽  
Jana Sperschneider ◽  
Benjamin Schwessinger ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
De Novo ◽  
Rust Fungus ◽  
Expression Patterns ◽  
Haplotype Diversity ◽  
Crown Rust ◽  
Puccinia Coronata ◽  
Small Subset ◽  
Nucleotide Polymorphisms ◽  
Oat Crown Rust

AbstractOat crown rust, caused by the fungus Puccinia coronata f. sp. avenae (Pca), is a devastating disease that impacts worldwide oat production. For much of its life cycle, Pca is dikaryotic, with two separate haploid nuclei that may vary in virulence genotype, highlighting the importance of understanding haplotype diversity in this species. We generated highly contiguous de novo genome assemblies of two Pca isolates, 12SD80 and 12NC29, from long-read sequences. In total, we assembled 603 primary contigs for a total assembly length of 99.16 Mbp for 12SD80 and 777 primary contigs with a total length of 105.25 Mbp for 12NC29, and approximately 52% of each genome was assembled into alternate haplotypes. This revealed structural variation between haplotypes in each isolate equivalent to more than 2% of the genome size, in addition to about 260,000 and 380,000 heterozygous single-nucleotide polymorphisms in 12SD80 and 12NC29, respectively. Transcript-based annotation identified 26,796 and 28,801 coding sequences for isolates 12SD80 and 12NC29, respectively, including about 7,000 allele pairs in haplotype-phased regions. Furthermore, expression profiling revealed clusters of co-expressed secreted effector candidates, and the majority of orthologous effectors between isolates showed conservation of expression patterns. However, a small subset of orthologs showed divergence in expression, which may contribute to differences in virulence between 12SD80 and 12NC29. This study provides the first haplotype-phased reference genome for a dikaryotic rust fungus as a foundation for future studies into virulence mechanisms in Pca.ImportanceDisease management strategies for oat crown rust are challenged by the rapid evolution of Puccinia coronata f. sp. avenae (Pca), which renders resistance genes in oat varieties ineffective. Despite the economic importance of understanding Pca, resources to study the molecular mechanisms underpinning pathogenicity and emergence of new virulence traits are lacking. Such limitations are partly due to the obligate biotrophic lifestyle of Pca as well as the dikaryotic nature of the genome, features that are also shared with other important rust pathogens. This study reports the first release of a haplotype-phased genome assembly for a dikaryotic fungal species and demonstrates the amenability of using emerging technologies to investigate genetic diversity in populations of Pca.

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