Importance de l’intéraction entre les cultivars de blé et les souches du Fusarium graminearum dans l’évaluation de la résistance à la fusariose de l’épi

Des expériences factorielles ont été réalisées au champ à deux stations, le campus de l'Université Laval en 1991 et 1992 et la ferme de Saint-Louis-de-Pintendre en 1992 et 1993, pour préciser si le développement de la fusariose de l'épi du blé est influencé par l'interaction entre les cultivars et les souches du Fusarium graminearum. Neuf souches du F. graminearum ont été inoculées à onze cultivars de blé (Triticum aestivum) et un cultivar de triticale (x Triticosecale) représentatifs de la gamme de sensibilité à cette maladie au Québec. L'analyse de la variance combinée a mis en évidence des interactions significatives entre les cultivars, les souches et les environnements. Les interactions cultivars x souches et cultivars x environnements expliquent une faible proportion de la somme des carrés totale et n'entraînent pas de modifications majeures dans le classement moyen de la sensibilité des cultivars. Concernant l'interaction cultivars x souches, le classement moyen de la sensibilité des cultivars, notamment Casavant et Concorde, variait avec les souches. Cette recherche contre pour la première fois que l'importance relative des différentes interactions entre les souches, les cultivars et les environnements est comparable dans l'évaluation de la résistance à la fusariose de l'épi du blé.Factorial experiments were carried out in the field at the campus of Universite Laval in 1991 and 1992, and Saint-Louis-de-Pintendre station in 1992 and 1993. The objective was to specify if wheat scab development caused by Fusarium graminearum is significantly affected by cultivar x strain interactions. Eleven wheat (Triticum aestivum) cultivars and one triticale (x Triticosecale) cultivar representing the range of sensitivity to this disease in Quebec were inoculated with nine strains of F. graminearum. Significant interactions between cultivars, strains and environments were shown by the results of a combined analysis of variance. Cultivar x strain and cultivar x environment interactions explained a small proportion of the total sum of squares and did not have a strong impact on cultivar average ranking by environment or strain. However, the examination of cultivar x strain interactions revealed that the rank of cultivars such as Casavant and Concorde changed when different strains were compared. This research shows for the first time that all interactions involving cultivars, strains and environments have a similar impact on wheat scab resistance screening

Importance de l’intéraction entre les cultivars de blé et les souches du Fusarium graminearum dans l’évaluation de la résistance à la fusariose de l’épi

Des expériences factorielles ont été réalisées au champ à deux stations, le campus de l'Université Laval en 1991 et 1992 et la ferme de Saint-Louis-de-Pintendre en 1992 et 1993, pour préciser si le développement de la fusariose de l'épi du blé est influencé par l'interaction entre les cultivars et les souches du Fusarium graminearum. Neuf souches du F. graminearum ont été inoculées à onze cultivars de blé (Triticum aestivum) et un cultivar de triticale (x Triticosecale) représentatifs de la gamme de sensibilité à cette maladie au Québec. L'analyse de la variance combinée a mis en évidence des interactions significatives entre les cultivars, les souches et les environnements. Les interactions cultivars x souches et cultivars x environnements expliquent une faible proportion de la somme des carrés totale et n'entraînent pas de modifications majeures dans le classement moyen de la sensibilité des cultivars. Concernant l'interaction cultivars x souches, le classement moyen de la sensibilité des cultivars, notamment Casavant et Concorde, variait avec les souches. Cette recherche contre pour la première fois que l'importance relative des différentes interactions entre les souches, les cultivars et les environnements est comparable dans l'évaluation de la résistance à la fusariose de l'épi du blé.Factorial experiments were carried out in the field at the campus of Universite Laval in 1991 and 1992, and Saint-Louis-de-Pintendre station in 1992 and 1993. The objective was to specify if wheat scab development caused by Fusarium graminearum is significantly affected by cultivar x strain interactions. Eleven wheat (Triticum aestivum) cultivars and one triticale (x Triticosecale) cultivar representing the range of sensitivity to this disease in Quebec were inoculated with nine strains of F. graminearum. Significant interactions between cultivars, strains and environments were shown by the results of a combined analysis of variance. Cultivar x strain and cultivar x environment interactions explained a small proportion of the total sum of squares and did not have a strong impact on cultivar average ranking by environment or strain. However, the examination of cultivar x strain interactions revealed that the rank of cultivars such as Casavant and Concorde changed when different strains were compared. This research shows for the first time that all interactions involving cultivars, strains and environments have a similar impact on wheat scab resistance screening

Report of IDRC Board Review Panel - CO-OP

French version available in IDRC Digital Library: Rapport du Comité du conseil chargé de l'étude de la Division P

Diverse Lifestyles and Strategies of Plant Pathogenesis Encoded in the Genomes of Eighteen Dothideomycetes Fungi

The class Dothideomycetes is one of the largest groups of fungi with a high level of ecological diversity including many plant pathogens infecting a broad range of hosts. Here, we compare genome features of 18 members of this class, including 6 necrotrophs, 9 (hemi)biotrophs and 3 saprotrophs, to analyze genome structure, evolution, and the diverse strategies of pathogenesis. The Dothideomycetes most likely evolved from a common ancestor more than 280 million years ago. The 18 genome sequences differ dramatically in size due to variation in repetitive content, but show much less variation in number of (core) genes. Gene order appears to have been rearranged mostly within chromosomal boundaries by multiple inversions, in extant genomes frequently demarcated by adjacent simple repeats. Several Dothideomycetes contain one or more gene-poor, transposable element (TE)-rich putatively dispensable chromosomes of unknown function. The 18 Dothideomycetes offer an extensive catalogue of genes involved in cellulose degradation, proteolysis, secondary metabolism, and cysteine-rich small secreted proteins. Ancestors of the two major orders of plant pathogens in the Dothideomycetes, the Capnodiales and Pleosporales, may have had different modes of pathogenesis, with the former having fewer of these genes than the latter. Many of these genes are enriched in proximity to transposable elements, suggesting faster evolution because of the effects of repeat induced point (RIP) mutations. A syntenic block of genes, including oxidoreductases, is conserved in most Dothideomycetes and upregulated during infection in L. maculans, suggesting a possible function in response to oxidative stress

The Genomes of the Fungal Plant Pathogens Cladosporium fulvum and Dothistroma septosporum Reveal Adaptation to Different Hosts and Lifestyles But Also Signatures of Common Ancestry

We sequenced and compared the genomes of the Dothideomycete fungal plant pathogens Cladosporium fulvum (Cfu) (syn. Passalora fulva) and Dothistroma septosporum (Dse) that are closely related phylogenetically, but have different lifestyles and hosts. Although both fungi grow extracellularly in close contact with host mesophyll cells, Cfu is a biotroph infecting tomato, while Dse is a hemibiotroph infecting pine. The genomes of these fungi have a similar set of genes (70% of gene content in both genomes are homologs), but differ significantly in size (Cfu >61.1-Mb; Dse 31.2-Mb), which is mainly due to the difference in repeat content (47.2% in Cfu versus 3.2% in Dse). Recent adaptation to different lifestyles and hosts is suggested by diverged sets of genes. Cfu contains an a-tomatinase gene that we predict might be required for detoxification of tomatine, while this gene is absent in Dse. Many genes encoding secreted proteins are unique to each species and the repeat-rich areas in Cfu are enriched for these species-specific genes. In contrast, conserved genes suggest common host ancestry. Homologs of Cfu effector genes, including Ecp2 and Avr4, are present in Dse and induce a Cf-Ecp2- and Cf-4-mediated hypersensitive response, respectively. Strikingly, genes involved in production of the toxin dothistromin, a likely virulence factor for Dse, are conserved in Cfu, but their expression differs markedly with essentially no expression by Cfu in planta. Likewise, Cfu has a carbohydrate-degrading enzyme catalog that is more similar to that of necrotrophs or hemibiotrophs and a larger pectinolytic gene arsenal than Dse, but many of these genes are not expressed in planta or are pseudogenized. Overall, comparison of their genomes suggests that these closely related plant pathogens had a common ancestral host but since adapted to different hosts and lifestyles by a combination of differentiated gene content, pseudogenization, and gene regulatio

Rapport du Comité du conseil chargé de l'étude de la Division PC

Version anglaise disponible dans la Bibliothèque numérique du CRDI: Report of IDRC Board Review Panel - CO-O

Rapid identification and detection of pathogenic Fungi by padlock probes

Fungi are important pathogens of human diseases, as well as to agricultural crop and trees. Molecular diagnostics can detect diseases early, and improve identification accuracy and follow-up disease management. The use of padlock probe is effective to facilitate these detections and pathogen identification quickly and accurately. In this chapter we describe three diagnostic assays that utilize padlock probes in combination with various technologies for the detection of pathogenic fungi

Approaches to molecular characterization of fungal biocontrol agents: Some case studies

An increasing number of fungal biocontrol agents are being developed for control of pests in agriculture and forestry. The use of these living organisms has brought new challenges in research and development of biocontrol products. Molecular markers provide immense sources of data that can assist scientists in developing tools to monitor the genetic and environmental fate of these agents. Selection of appropriate molecular techniques should be based on the specific characteristics of the organism and on the desired type of information necessary to evaluate a particular step in the developmental process of a biopesticide. Genetic assessment of fungal antagonists is not only desirable but essential to gain insight into the safe and reliable use of biological control products