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Gray Mold Populations in German Strawberry Fields Are Resistant to Multiple Fungicides and Dominated by a Novel Clade Closely Related to Botrytis cinerea

Leroch, Michaela; Plesken, Cecilia; Weber, Roland W. S.; Kauff, Frank; Scalliet, Gabriel; Hahn, Matthias
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /01/2013 EN
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The gray mold fungus Botrytis cinerea is a major threat to fruit and vegetable production. Strawberry fields usually receive several fungicide treatments against Botrytis per season. Gray mold isolates from several German strawberry-growing regions were analyzed to determine their sensitivity against botryticides. Fungicide resistance was commonly observed, with many isolates possessing resistance to multiple (up to six) fungicides. A stronger variant of the previously described multidrug resistance (MDR) phenotype MDR1, called MDR1h, was found to be widely distributed, conferring increased partial resistance to two important botryticides, cyprodinil and fludioxonil. A 3-bp deletion mutation in a transcription factor-encoding gene, mrr1, was found to be correlated with MDR1h. All MDR1h isolates and the majority of isolates with resistance to multiple fungicides were found to be genetically distinct. Multiple-gene sequencing confirmed that they belong to a novel clade, called Botrytis group S, which is closely related to B. cinerea and the host-specific species B. fabae. Isolates of Botrytis group S genotypes were found to be widespread in all German strawberry-growing regions but almost absent from vineyards. Our data indicate a clear subdivision of gray mold populations...

Comparative Analysis of Defense Responses in Chocolate Spot-Resistant and -Susceptible Faba Bean (Vicia faba) Cultivars Following Infection by the Necrotrophic Fungus Botrytis fabae

El-Komy, Mahmoud H.
Fonte: Korean Society of Plant Pathology Publicador: Korean Society of Plant Pathology
Tipo: Artigo de Revista Científica
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In this study, resistance responses were investigated during the interaction of Botrytis fabae with two faba bean cultivars expressing different levels of resistance against this pathogen, Nubaria (resistant) and Giza 40 (susceptible). Disease severity was assessed on leaves using a rating scale from 1 to 9. Accumulation levels of reactive oxygen species (ROS), lipid peroxidation and antioxidant enzymes (superoxide dismutase, catalase and ascorbate peroxidase) were measured in leaf tissues at different times of infection. The expression profiles of two pathogenesis-related proteins (PRPs) encoded by the genes PR-1 and β-1,3-glucanase were also investigated using reverse transcription RT-PCR analysis. The accumulation of these defense responses was induced significantly in both cultivars upon infection with B. fabae compared with un-inoculated controls. The resistant cultivar showed weaker necrotic symptom expression, less ROS accumulation, a lower rate of lipid peroxidation and higher activity of the enzymatic ROS scavenging system compared with susceptible cultivar. Interestingly, ROS accumulated rapidly in the resistant leaf tissues and peaked during the early stages of infection, whereas accumulation was stronger and more intense in the susceptible tissues in later stages. Moreover...

Reducing management inputs and maximising seed quality in faba beans through improved varieties

Egan, J.; McMurray, L.; Paull, J.; Davidson, J.; Crouch, J.
Fonte: The Regional Institute Ltd; Online Publicador: The Regional Institute Ltd; Online
Tipo: Conference paper
Publicado em //2006 EN
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Faba beans (Vicia faba L.) are a valuable break crop in southern Australia and the most profitable pulse on heavy soils prone to transient waterlogging in medium to high rainfall areas. Previous research indicates faba beans require early sowing to maximise yields and hence they are often dry sown before the season break. This increases crop exposure to disease infection, particularly ascochyta blight (Ascochyta fabae), chocolate spot (Botrytis fabae) and cercospora leaf spot (Cercospora zonata). Older cultivars (cv Fiord and Fiesta VF) have only low to moderate resistance to these diseases. Fungicides are expensive and not always entirely effective for disease control, resulting in reduced profitability through yield loss and quality downgrading. To improve yield stability and productivity the National Faba Bean Improvement Program has developed varieties with improved disease resistance and seed quality. Field experiments were conducted at two sites in South Australia to develop cost-effective disease management strategies for the new cultivars Farah and Nura. Disease levels were low to moderate in these experiments. Both new cultivars had lower levels of ascochyta blight foliar disease and seed staining than Fiesta VF, while Nura also had lower chocolate spot infection. Fungicide sprays generally reduced disease levels...

Identification of sources of disease resistance in Chinese faba bean germplasm for incorporation in Australian cultivars.

Jamali, Ali Raza
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2009
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A total of 115 Chinese accessions from six provinces with diverse climate, topography and farming systems were screened for reaction to three fungal diseases Ascochyta blight, (Acochyta fabae), chocolate spot (Botrytis fabae) and Cercospora leaf spot (Cercospora zonata). Not all the accessions were included in three disease screening trials due to a limited number of seeds for some accessions. However, a majority of lines were included in all three disease screening trials and the remaining at least for two trials. In the Ascochyta blight screening trial 96 Chinese accessions were evaluated and while the majority of lines were susceptible a number of lines including 1688, 1689 (Gansu), 1729 (Guangxi), 1750 (Jiangsu), 1998 and 1999 (Qinghai) were identified with a significant degree of heterogeneity including a low proportion of resistant plants. Single plants with a disease score of either 1 (resistant) or 3 (moderately resistant) could be used for the development and selection of resistant lines. The effect of three concentrations of B. fabae inoculum was observed on four cultivars 1714-1, Nura, Fiesta and Icarus. The disease development was proportional to the amount of inoculum irrespective of cultivars but the relative responses of cultivars varied between treatments...