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Martin L Carson - One of the best experts on this subject based on the ideXlab platform.
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screening wild oat accessions from morocco for resistance to Puccinia coronata
Plant Disease, 2013Co-Authors: Martin L CarsonAbstract:Abstract Here, we report the screening of 332 new accessions of 11 different wild oat (Avena) species from the United States Department of Agriculture National Small Grains Collection in Aberdeen, ID, for resistance to crown rust disease, caused by Puccinia coronata f. sp. avenae. This collection originated from Morocco and includes Avena agadiriana, A. atlantica, A. barbata, A. damascena, A. eriantha, A. hirtula, A. longiglumis, A. magna, A. murphyi, A. sterilis, and A. wiestii. After screening this collection with a highly diverse population of P. coronata f. sp. avenae, 164 accessions (49%) were rated moderately resistant to resistant in the preliminary screen at the seedling stage and 181 accessions (55%) rated moderately resistant to highly resistant in the adult plant stage. Although none of the accessions showed a highly resistant response consistently in the seedling stage, 20 accessions did display a highly resistant response in the adult plant stage. Both seedling as well as adult plant resistan...
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virulence in oat crown rust Puccinia coronata f sp avenae in the united states from 2006 through 2009
Plant Disease, 2011Co-Authors: Martin L CarsonAbstract:Abstract The use of race-specific seedling genes for resistance is the primary means of controlling crown rust of oat (Puccinia coronata f. sp. avenae) in the United States. To better utilize those resistance genes, knowledge of the occurrence and frequency of corresponding virulence in the population of P. coronata f. sp. avenae in the United States is essential. In total, 571 single-pustule isolates of oat crown rust were collected from cultivated and wild oat (Avena sativa and A. fatua, respectively) in the major oat production areas of the United States from 2006 through 2009. They were tested for virulence on seedlings of 31 differential oat lines in the greenhouse. In all, 201 races were found among the 357 isolates from the spring oat region of the north-central United States, and 140 races were found among 214 isolates from the southern winter oat region. The crown rust populations from the winter and spring oat regions were clearly differentiated from one another, differing in the frequency of vi...
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additional sources of broad spectrum resistance to Puccinia coronata f sp avenae from canadian accessions of avena barbata
Plant Disease, 2010Co-Authors: Martin L CarsonAbstract:ABSTRACT Crown rust (Puccinia coronata f. sp. avenae) is considered the most damaging disease of oat and the use of race-specific seedling (Pc) genes for resistance has been the primary means of control. As these resistance genes from cultivated oat, Avena sativa, and the wild hexaploid animated oat, A. sterilis, were deployed in oat cultivars, corresponding virulence in the U.S. crown rust population increased rapidly, such that the effective lifespan of a resistant cultivar in the United States is now 5 years or less. Introgression of resistance from diploid and tetraploid Avena spp. into hexaploid oat has been difficult due to the difference in ploidy levels and the lack of pairing of homeologous chromosomes between species. The wild tetraploid slender oat, A. barbata, has been a source of powdery mildew and stem rust resistance in cultivated oat but has largely been unexploited for crown rust resistance. A relatively high percentage of A. barbata accessions from the United States Department of Agricul...
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broad spectrum resistance to crown rust Puccinia coronata f sp avenae in accessions of the tetraploid slender oat avena barbata
Plant Disease, 2009Co-Authors: Martin L CarsonAbstract:Carson, M. L. 2009. Broad-spectrum resistance to crown rust, Puccinia coronata f. sp. avenae, in accessions of the tetraploid slender oat, Avena barbata. Plant Dis. 93:363-366. The use of race-specific seedling genes for resistance has been the primary means of controlling crown rust of oat (Puccinia coronata). As resistance genes from hexaploid cultivated oat, Avena sativa and, later, the wild hexaploid animated oat, A. sterilis, were deployed in oat cultivars, corresponding virulence in the crown rust population increased rapidly, such that the effective lifespan of a resistant cultivar in the United States is now 5 years or less. Introgression of resistance genes from diploid and tetraploid Avena spp. into hexaploid oat has been difficult due to differences in ploidy levels and the lack of homology of chromosomes between the two species. The wild tetraploid slender oat, A. barbata, has been a source of powdery mildew and stem rust resistance in cultivated oat but has largely been unexploited for crown rust resistance. In total, 359 accessions of A. barbata from the National Small Grains Collection were evaluated in seedling greenhouse tests. Of these accessions, 39% were at least moderately resistant when inoculated with a crown rust race with low virulence (DBBC). When tested further with a highly diverse bulk inoculum from the 2006 and 2007 St. Paul buckthorn nursery, 48 accessions (approximately 13%) were resistant. Many of these accessions were heterogeneous in reaction, but two accessions (PI320588 from Israel and PI337893 from Italy) were highly resistant (immune) and two others (PI337886 from Italy and PI367293 from Spain) consistently produced resistant reactions (chlorotic flecks) in all tests. Resistant accessions were found from throughout much of the natural range of A. barbata. Crosses of some of the better accessions have been made to cultivated oat.
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crown rust development and selection for virulence in Puccinia coronata f sp avenae in an oat multiline cultivar
Plant Disease, 2009Co-Authors: Martin L CarsonAbstract:ABSTRACT Crown rust, caused by Puccinia coronata f. sp. avenae is the most important disease of cultivated oat in North America. Numerous race-specific (Pc) genes for crown rust have been found in Avena spp. but this type of resistance has not been durable when used in oat cultivars. Increasing diversity for resistance within a crop by the use of multiline cultivars or varietal mixtures has been proposed as a means of achieving durable resistance to highly variable pathogens such as P. coronata f. sp. avenae. Multiline cv. E77 was evaluated over multiple seasons in the University of Minnesota buckthorn nursery in St. Paul. Buckthorn (Rhamnus cathartica, the alternate host of P. coronata) supports a sexually recombining, highly diverse crown rust population in the St. Paul nursery. Crown rust severity on flag leaves was measured multiple times on E77 and its 10 component lines during grain filling. Single-urediniospore isolates taken from crown rust samples during early stages of the epidemic and at the en...
K J Leonard - One of the best experts on this subject based on the ideXlab platform.
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persistent virulence associations in sexual populations of Puccinia coronata
Plant Pathology, 2007Co-Authors: K J LeonardAbstract:From 1992 to 1999, 18 sets of aecial or uredinial isolates of Puccinia coronata were collected from two sites in Minnesota for analysis of virulence associations. In addition, one set of aecial isolates was collected in Ontario and one in New York. Also, aecial isolates and uredinial isolates collected from scattered locations in Minnesota in 1994 and again in 1995 were bulked for comparison with populations from discrete sites. Isolates were tested for virulence on 26 single-Pc gene oat lines. Virulences to 14 pairs of differential lines were found to be significantly (P < 0·05) associated in linkage disequilibrium in at least six of the 24 site × year populations. The significant virulence associations were found among both uredinial and aecial isolates. Linkage disequilibria normally dissipate with repeated generations of sexual reproduction. Finding the same virulence associations repeatedly over years and locations for sexual populations of P. coronata indicates that certain pairs of virulence genes (or avirulence genes) contribute to increased fitness when they occur together, even in the absence of the corresponding resistance genes in the host. Mean virulence complexity did not differ significantly between a site with no known Pc genes in the host population and a site with low frequencies of Pc genes, suggesting little or no selection pressure against unnecessary virulence per se. Means and standard deviations of virulence complexity were similar for aecial and uredinial isolates within sites, which suggests that selection did not strongly favour either heterozygotes or intermediate virulence complexity during uredinial generations.
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Persistent virulence associations in sexual populations of Puccinia coronata
Plant Pathology, 2007Co-Authors: K J LeonardAbstract:From 1992 to 1999, 18 sets of aecial or uredinial isolates of Puccinia coronata were collected from two sites in Minnesota for analysis of virulence associations. In addition, one set of aecial isolates was collected in Ontario and one in New York. Also, aecial isolates and uredinial isolates collected from scattered locations in Minnesota in 1994 and again in 1995 were bulked for comparison with populations from discrete sites. Isolates were tested for virulence on 26 single-Pc gene oat lines. Virulences to 14 pairs of differential lines were found to be significantly (P
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quantitative trait loci for partial resistance to crown rust Puccinia coronata in cultivated oat avena sativa l
Theoretical and Applied Genetics, 2005Co-Authors: V A Portyanko, K J Leonard, G Chen, H W Rines, Ronald L Phillips, G E Ochocki, D D StuthmanAbstract:To facilitate the detection of quantitative trait loci (QTLs) for partial resistance to oat crown rust, Puccinia coronata f. sp. avenae Eriks., a genetic map was generated in a population of 158 F6-derived oat recombinant inbred lines from a cross of a partial resistance line MN841801-1 by a susceptible cultivar selection ‘Noble-2’. The map, developed using 230 marker loci, mostly restriction fragment length polymorphism and amplified fragment length polymorphism markers, spanned 1,509 cM (Haldane) arranged into 30 linkage groups of 2–18 markers each. Four consistently detected major QTLs for partial rust resistance, Prq1a, Prq1b, Prq2, and Prq7, and three minor QTLs, Prq3, Prq5, and Prq6, were found in tests involving three field and two greenhouse environments. In addition, two major QTLs for flowering time, Ftq1 and Ftq7, and five weaker QTLs, Ftq2, Ftq3, Ftq4, Ftq5, and Ftq6, were revealed. Overlapping of the map segments of Ftq1 and Prq1 and of Ftq7 and Prq7 suggested either linkage between the flowering time QTLs and resistance QTLs or a pleiotropic effect of the Ftq QTLs on rust resistance. Relatively low heritability estimates (0.30) obtained for partial resistance to crown rust in the field indicate a potential value for marker-assisted selection.
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self fertility and other distinguishing characteristics of a new morphotype of Puccinia coronata pathogenic on smooth brome grass
Mycologia, 2003Co-Authors: Y Anikster, Tamar Eilam, J Manisterski, K J LeonardAbstract:A new morphotype of Puccinia coronata, pathogenic to Bromus inermis, a common roadside and pasture grass in the northern United States, was discovered in the 1990s and described as P. coronata f. sp. bromi by Delgado et al in 2001. Puccinia coronata f. sp. bromi does not require fertilization of pycnia to produce aecia on its alternate host, whereas fertiliza- tion is required in all other varieties or formae spe- ciales of P. coronata with aecial hosts in the family Rhamnaceae and for which life cycles have been de- scribed. Promycelia of P. coronata f. sp. bromi produce only two basidiospores, and each receives a pair of nuclei from the promycelium. The nuclei divide again so that mature basidiospores each contain four nuclei. Puccinia coronata f. sp. bromi has smaller te- liospores than P. coronata var. avenae, and its substo- matal vesicles are non-septate and distinctly shaped compared to those of P. coronata var. avenae .I n ad- dition, nuclei of P. coronata f. sp. bromi contain less DNA than those of P. coronata var. avenae. Puccinia coronata f. sp. bromi is further distinguished from P. coronata var. avenae and P. coronata var. hordei in be- ing avirulent on both oat and barley, whereas neither P. coronata var. avenae nor P. coronata var. hordei are virulent on Bromus inermis.
J Manisterski - One of the best experts on this subject based on the ideXlab platform.
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patterns of virulence in natural populations of Puccinia coronata on wild oat in israel and in agricultural populations on cultivated oat in the united states
Phytopathology, 2004Co-Authors: Kurt J Leonard, Y Anikster, J ManisterskiAbstract:Leonard, K. J., Anikster, Y., and Manisterski, J. 2004. Patterns of virulence in natural populations of Puccinia coronata on wild oat in Israel and in agricultural populations on cultivated oat in the United States. Phytopathology 94:505-514. Crown rust (Puccinia coronata) in indigenous populations of Avena sterilis has been cited as an example of stability of wild pathosystems that consist of natural mixtures of resistance and virulence. This study confirmed that virulence/avirulence polymorphisms in P. coronata on A. sterilis in Israel are highly diverse and that super races do not dominate. Isolates of P. coronata from Israel in 1991 to 1996 were polymorphic for virulence to 35 of 36 differential oat lines with resistance genes from A. sterilis. On average, isolates of P. coronata were more highly virulent to differentials with Pc genes from A. sterilis accessions from Israel than to differentials with Pc genes from other countries. Isolates from Israel also were more virulent on average to 10 additional differentials with Pc genes derived from A. sativa than to differentials with Pc genes from A. sterilis. Frequencies of virulence were usually higher in collections of P. coronata from Israel than in collections from cultivated oat in the United States, even though several of the Pc genes in the differentials have been used extensively in American oat cultivars. Mean virulence complexity of P. coronata from eight regions of Israel was not correlated with the distribution of resistance among collections of A. sterilis from previous surveys in the same areas, probably because pathogen migration between regions within Israel is sufficient to obscure effects of selection locally. Additional keywords: balancing selection, center of origin, host-parasite coevolution.
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incidence of crown rust and virulence of Puccinia coronata cda f sp avenae eriks and the effectiveness of pc genes for resistance in europe middle east and north africa inzidenz von kronenrost und virulenz von Puccinia coronata cda f sp avenae eriks
Archives of Phytopathology and Plant Protection, 2003Co-Authors: J Sebesta, H W Roderick, J Manisterski, B Zwatz, L Corazza, S StojanovicAbstract:Crown rust on oat incited by Puccinia coronata Cda f.sp. avenae is a wide-spread disease in Europe, Middle East (Israel) and North Africa (Morocco). High natural levels of the disease were recorded in Austria, Bulgaria, Czech Republic, Estonia, Israel, Italy, Poland, Russia and the former Yugoslavia. The severity of the disease in the European and Mediterranean Oat Disease Nursery (EMODN) between 1995 and 1999 showed that it occurred at damaging levels in a number of countries. Considerable differences in a disease resistance index (DRI) to crown rust among 67 oat lines in the period 1995 – 2000 were found. The values of the DRI ranged from18 (KR 8122) to over 290 (Pc 59, Pc 68). Detailed studies of the virulence combinations of P.coronata f.sp. avenae in Europe, Middle East and North Africa were carried out between 1995 – 2001. There were considerable differences in the average number of virulence among countries. Virulence to Pc 39 and 68 was found for the first time and is a significant finding. Nevert...
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self fertility and other distinguishing characteristics of a new morphotype of Puccinia coronata pathogenic on smooth brome grass
Mycologia, 2003Co-Authors: Y Anikster, Tamar Eilam, J Manisterski, K J LeonardAbstract:A new morphotype of Puccinia coronata, pathogenic to Bromus inermis, a common roadside and pasture grass in the northern United States, was discovered in the 1990s and described as P. coronata f. sp. bromi by Delgado et al in 2001. Puccinia coronata f. sp. bromi does not require fertilization of pycnia to produce aecia on its alternate host, whereas fertiliza- tion is required in all other varieties or formae spe- ciales of P. coronata with aecial hosts in the family Rhamnaceae and for which life cycles have been de- scribed. Promycelia of P. coronata f. sp. bromi produce only two basidiospores, and each receives a pair of nuclei from the promycelium. The nuclei divide again so that mature basidiospores each contain four nuclei. Puccinia coronata f. sp. bromi has smaller te- liospores than P. coronata var. avenae, and its substo- matal vesicles are non-septate and distinctly shaped compared to those of P. coronata var. avenae .I n ad- dition, nuclei of P. coronata f. sp. bromi contain less DNA than those of P. coronata var. avenae. Puccinia coronata f. sp. bromi is further distinguished from P. coronata var. avenae and P. coronata var. hordei in be- ing avirulent on both oat and barley, whereas neither P. coronata var. avenae nor P. coronata var. hordei are virulent on Bromus inermis.
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incidence of crown rust and virulence of Puccinia coronata cda f sp avenae eriks and the effectiveness of pc genes for resistance in europe middle east and north africa
2003Co-Authors: J Sebesta, H W Roderick, J Manisterski, B Zwatz, L Corazza, S StojanovicAbstract:Sebesta, J., Zwatz, B., Roderick, H. W., Corazza, L., Manisterski, J., Stojanovic, S. (2003). Incidence of crown rust and virulence of Puccinia coronata Cda. f.sp. avenae Eriks. and the effectiveness of PC genes for resistance in Europe, Middle East and North Africa. Archives of Phytopathology and Plant Protection, 36, (3& 4),179-194.
Melania Figueroa - One of the best experts on this subject based on the ideXlab platform.
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detection of race specific resistance against Puccinia coronata f sp avenae in brachypodium species
Phytopathology, 2018Co-Authors: Vahid Omidvar, Feng Li, Shahryar F Kianian, Sheshanka Dugyala, Susan M Rottschaefer, Marisa E Miller, Michael Ayliffe, Matthew J Moscou, Melania FigueroaAbstract:: Oat crown rust caused by Puccinia coronata f. sp. avenae is the most destructive foliar disease of cultivated oat. Characterization of genetic factors controlling resistance responses to Puccinia coronata f. sp. avenae in nonhost species could provide new resources for developing disease protection strategies in oat. We examined symptom development and fungal colonization levels of a collection of Brachypodium distachyon and B. hybridum accessions infected with three North American P. coronata f. sp. avenae isolates. Our results demonstrated that colonization phenotypes are dependent on both host and pathogen genotypes, indicating a role for race-specific responses in these interactions. These responses were independent of the accumulation of reactive oxygen species. Expression analysis of several defense-related genes suggested that salicylic acid and ethylene-mediated signaling but not jasmonic acid are components of resistance reaction to P. coronata f. sp. avenae. Our findings provide the basis to conduct a genetic inheritance study to examine whether effector-triggered immunity contributes to nonhost resistance to P. coronata f. sp. avenae in Brachypodium spp.
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Puccinia coronata f sp avenae a threat to global oat production
Molecular Plant Pathology, 2018Co-Authors: Eric S Nazareno, Feng Li, Madeleine J Smith, R F Park, Shahryar F Kianian, Melania FigueroaAbstract:SUMMARY Puccinia coronata f. sp. avenae (Pca) causes crown rust disease in cultivated and wild oat (Avena spp.). The significant yield losses inflicted by this pathogen makes crown rust the most devastating disease in the oat industry. Puccinia coronata f. sp. avenae is a basidiomycete fungus with an obligate biotrophic lifestyle and is classified as a typical macrocyclic and heteroecious fungus. The asexual phase in the life cycle of Pca occurs in oat while the sexual phase occurs primarily in Rhamnus species as the alternate host. Epidemics of crown rust occur in areas with warm temperatures (20 to 25°C) and high humidity. Infection by the pathogen leads to plant lodging and shriveled grain of poor quality. Disease symptoms. Infection of susceptible oat varieties gives rise to orange-yellow round-to-oblong uredinia (pustules) containing newly formed urediniospores. Pustules vary in size and can be larger than five mm in length. Infection occurs primarily on the surfaces of leaves, although occasional symptoms develop in the oat leaf sheaths and/or floral structures like awns. Symptoms in resistant oat varieties vary from flecks to small pustules, typically accompanied by chlorotic halos and/or necrosis. The pycnial and aecial stages are mostly present in the leaves of Rhamnus species, but occasionally symptoms can also be observed in petioles, young stems, and floral structures. Aecial structures display a characteristic hypertrophy and can differ in size, occasionally reaching more than five mm in diameter. Taxonomy. Puccinia coronata f. sp. avenae (Pca) belongs to the kingdom Fungi, phylum Basidiomycota, class Pucciniomycetes, order Pucciniales, and family Pucciniaceae. Host range. P. coronata sensu lato can infect 290 species of grass hosts. Puccinia coronata f. sp. avenae is prevalent in all oat growing regions, and compared to other cereal rusts, it displays a broad telial host range. The most common grass hosts of Pca include cultivated hexaploid oat (Avena sativa) and wild relatives such as bluejoint grass, perennial ryegrass, and fescue. Alternate hosts include several species of Rhamnus, with R. cathartica (common buckthorn) as the most important alternate host in Europe and North America. Control. Most crown rust management strategies involve the use of rust-resistant crop varieties and application of fungicides. Attaining durability of resistance against Pca has been difficult for it is a highly variable pathogen with a great propensity to overcome the genetic resistance of varieties. Thus, adult plant resistance is often exploited in oat breeding programs to develop new crown rust-resistant varieties. Useful website: https://www.ars.usda.gov/midwest-area/st-paul-mn/cereal-disease-lab/docs/cereal-rusts/race-surveys/ This article is protected by copyright. All rights reserved.
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detection of race specific resistance against Puccinia coronata f sp avenae in brachypodium species
bioRxiv, 2018Co-Authors: Vahid Omidvar, Feng Li, Shahryar F Kianian, Sheshanka Dugyala, Susan M Rottschaefer, Marisa E Miller, Michael Ayliffe, Matthew J Moscou, Melania FigueroaAbstract:Oat crown rust caused by Puccinia coronata f. sp. avenae is the most destructive foliar disease of cultivated oat. Characterization of genetic factors controlling resistance responses to Puccinia coronata f. sp. avenae in non-host species could provide new resources for developing disease protection strategies in oat. We examined symptom development and fungal colonization levels of a collection of Brachypodium distachyon and B. hybridum accessions infected with three North American P. coronata f. sp. avenae isolates. Our results demonstrated that resistance phenotypes are dependent on both host and pathogen genotypes, indicating a role for race-specific responses in these interactions. These responses were independent of the accumulation of reactive oxygen species. Expression analysis of several defense-related genes suggested that salicylic acid and ethylene-mediated signaling, but not jasmonic acid are components of resistance reaction to P. coronata f. sp. avenae. Our findings suggest that effector-triggered immunity contributes to non-host resistance to P. coronata f. sp. avenae in Brachypodium species and provide the basis to conduct a genetic inheritance study to examine this hypothesis.
J Chong - One of the best experts on this subject based on the ideXlab platform.
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Virulence of Puccinia coronata f. sp. avenae in the Eastern Prairie Region of Canada during 2007–2009
Canadian Journal of Plant Pathology-revue Canadienne De Phytopathologie, 2011Co-Authors: J Chong, Janet Gruenke, Rebecca Dueck, Wayne Mayert, Jennifer Mitchell Fetch, Curt A MccartneyAbstract:Abstract Unfavourable environmental conditions for crown rust [Puccinia coronata f. sp. avenae] during 2007–2009 resulted in light incidence of crown rust on oat (Avena sativa) in Manitoba and eastern Saskatchewan. The first appearance of crown rust on 11 August in 2008 and on 15 August in 2009 was the latest ever seen in this region over the past three decades. Using 19 oat crown rust differentials, a large number of races were identified from isolates from wild oat each year, and a large proportion of the races were represented by a single isolate. There were significant differences between isolates from wild oat and cultivated oat in frequency of virulence to several genes in some years. Virulence frequency to Pc48, a gene in ‘Triple Crown’, was between 8.2–14.1% in isolates from wild oat and between 11.5–18.2% in isolates from cultivated oat during 2007–2009. Frequency of virulence to Pc68 was between 42.3–45.9% and 70.8–81.8% in isolates from wild oat and cultivated oat, respectively. As cultivars wi...
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virulence of Puccinia coronata f sp avenae in the eastern prairie region of canada during 2007 2009
Canadian Journal of Plant Pathology-revue Canadienne De Phytopathologie, 2011Co-Authors: J Chong, Janet Gruenke, Rebecca Dueck, Wayne Mayert, Jennifer Mitchell Fetch, Curt A MccartneyAbstract:Abstract Unfavourable environmental conditions for crown rust [Puccinia coronata f. sp. avenae] during 2007–2009 resulted in light incidence of crown rust on oat (Avena sativa) in Manitoba and eastern Saskatchewan. The first appearance of crown rust on 11 August in 2008 and on 15 August in 2009 was the latest ever seen in this region over the past three decades. Using 19 oat crown rust differentials, a large number of races were identified from isolates from wild oat each year, and a large proportion of the races were represented by a single isolate. There were significant differences between isolates from wild oat and cultivated oat in frequency of virulence to several genes in some years. Virulence frequency to Pc48, a gene in ‘Triple Crown’, was between 8.2–14.1% in isolates from wild oat and between 11.5–18.2% in isolates from cultivated oat during 2007–2009. Frequency of virulence to Pc68 was between 42.3–45.9% and 70.8–81.8% in isolates from wild oat and cultivated oat, respectively. As cultivars wi...
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detached leaf method for propagating Puccinia coronata and assessing crown rust resistance in oat
Plant Disease, 2008Co-Authors: E W Jackson, J Chong, D E Obert, J B Avant, J M BonmanAbstract:Jackson, E. W., Obert, D. E., Chong, J., Avant, J. B., and Bonman, J. M. 2008. Detached-leaf method for propagating Puccinia coronata and assessing crown rust resistance in oat. Plant Dis. 92:1400-1406. The crown rust pathogen Puccinia coronata is an obligate biotroph with wind-disseminated propagules and numerous races. These characteristics make propagation of single-race cultures difficult. Genetic studies using single races in field and greenhouse environments are also problematic because pure cultures can easily become contaminated. In this study, we developed an isolated propagation system for P. coronata and tested its ability to assess host resistance. Oat (Avena sativa) leaf sections (10 cm each) were harvested, disinfested, and suspended in sterile plastic boxes by enclosing 3.5-cm linear sections of each leaf end between 4% agar blocks amended with various chemical constituents. The exposed sections (approximately 3 cm) were inoculated with P. coronata urediniospores suspended in water. Boxes were sealed and incubated in a lighted growth cabinet until the pathogen sporulated. Viable spores were produced on leaves in all treatments, whereas 6-benzylaminopurine (BAP) and kinetin treatments sustained the leaves longer and yielded the most viable spores. Based on these data, the BAP treatment was adopted and used for additional studies. Detached leaves of differential oat cultivars produced the same reactions as whole plants screened under standard conditions in a growth chamber. The proposed detachedleaf system should be useful for the propagation of numerous single-race cultures of P. coronata as well as evaluation of host resistance under highly controlled conditions.
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physiologic specialization of Puccinia coronata f sp avenae the cause of oat crown rust in canada from 1999 to 2001
Canadian Journal of Plant Pathology-revue Canadienne De Phytopathologie, 2004Co-Authors: J Chong, T ZegeyeAbstract:Crown rust [Puccinia coronata f. sp. avenae] of oat (Avena sativa) was light in southern Manitoba in July in all 3 years during 1999–2001, but by mid-August in 1999 and 2001, heavy crown-rust infections (up to 90% severity) were found in late-planted fields of susceptible oat cultivars and in wild oat (Avena fatua) in Manitoba and eastern Saskatchewan. An important change in 2001 from previous years was the large increase in crown-rust severity (up to 90%) in late-planted fields of 'Triple Crown'. Crown-rust severity remained low on 'AC Assiniboia' during 1999–2001. Using 18 differential oat lines, the number of virulence phenotypes identified in the eastern prairies was 113 from 316 isolates in 1999, 111 from 260 isolates in 2000, and 112 from 217 isolates in 2001. From Ontario, 11 virulence phenotypes were identified from 25 isolates in 1999, 26 from 60 isolates in 2000, and 17 from 26 isolates in 2001. The Ontario and prairie rust populations were dominated by isolates having virulence to Pc38 and Pc39...
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incidence and virulence of Puccinia coronata f sp avenae in canada from 1996 to 1998
Canadian Journal of Plant Pathology-revue Canadienne De Phytopathologie, 2000Co-Authors: J ChongAbstract:Crown rust (Puccinia coronata f. sp. avenae) of oat (Avena sativa) was severe in Manitoba in 1996 and 1998 but was relatively mild in 1997. Heavy crown rust infections were also commonly found on wild oat (Avena fatua) in eastern Saskatchewan in 1996 and 1998. Warm weather with frequent dew periods favoured spread of the disease across southern Manitoba in 1996 and 1998. By early to mid-August, moderate to heavy infections (40-90%) were commonly found in fields of susceptible cultivars, such as Robert, Riel, Dumont, AC Preakness, and Jerry. Only trace levels of infections were found on the resistant cultivars AC Assiniboia, AC Medallion, and Triple Crown. From the eastern prairie region (Manitoba and eastern Saskatchewan), 142, 123, and 111 virulence phenotypes were identified, respectively, from 328, 255, and 265 isolates in 1996, 1997, and 1998. From Ontario, 13, 29, and 48 virulence phenotypes were identified, respectively, from 22, 81, and 106 isolates in 1996, 1997, and 1998. Isolates with virulence ...
