Assessment of phenotypic diversity of Plasmopara viticola on Vitis genotypes with different resistance

An Extended Leaf Disc Test for Virulence Assessment in Plasmopara Viticola and Detection of Downy Mildew Resistance in Vitis

“…For the phenotypic characterization of P. viticola strains, the leaf disc inoculation test published in 2013 [3] was applied with some modifications: i) to inoculate the leaf discs, 1000 sporangia were used instead of 10000; this reduced the amount of sporangia required for the assay without diminishing the infection efficiency; ii) the evaluation of the infection was performed 10 days after inoculation instead of 14 days with the effect that the risk of undesired secondary infections by other microorganisms was reduced. The characterization system was refined, separating the assessment of the sporulation and the necrosis using different symbols (Table 1).…”

“…In addition to changes in scoring symptoms, an extension of the host differentials is suggested. Compared to our previous assay [3], we increased the number of V. vinifera genotypes to four and added six more North American and…”

“…Due to the lack of natural resistance in the European grapevine Vitis vinifera against the new pathogen, chemical measures for disease control soon became necessary. Currently, increasing amounts of fungicides and multiple applications throughout the season are necessary for adequate disease control [2] and consequently, fungicide resistance is frequently found in pathogen populations of commercial vineyards [3]. On the other hand, sources for natural resistance are present in North American and Asiatic wild Vitis species such as V. riparia, V. ruspestris or V. amurensis, and have been used for breeding since the 19 th century [1,4,5].…”

Pathogenicity Variation and Population Genetic Structure of Plasmopara viticola in China

“…Based on the evaluation report of different grape species/cultivars against DM in our laboratory (Yu et al 2012), six grapevine genotypes of five Vitis species with different levels of DM resistance, including one Eurasian specie (DM-susceptible V. vinifera 'Cabernet Sauvignon'), one North America specie (resistant V. riparia 'DVIT1849'), four Oriental species (lowly resistant V. davidii '940', moderately resistant V. amurensis 'Zuoshan-1', highly resistant V. amurensis 'Shuanghong' and extremely resistant V. pseudoreticulata '1057'), were selected to test pathogenicity of the Pv strains. 1) (Yu et al 2012;G omez-Zeled on et al 2013). After propagation, sporangia of tested Pv strains were washed from sporulated leaf discs and adjusted to 1 9 10 4 sporangia/ml with sterile water.…”

A specific allele of MYB14 in grapevine correlates with high stilbene inducibility triggered by Al3+ and UV-C radiation

“…For instance, V. labrusca ‘Concord’ is characterized as a pathogen-resistant genotype (Pearson and Gadoury 1992; Pearson and Goheen 1988), while V. vinifera ‘Cabernet Sauvignon’ is relatively pathogen-sensitive (Boso and Kassemeyer 2008; Marsh et al 2010). However, due to the extended coevolution of grapevines and pathogens, some American grapevines, such as the V. labrusca ‘Concord’, which is known for its ability to resist the destructive disease ‘powdery mildew’, now suffer from infection by pathogens, such as Plasmopara viticola strains (Gadoury et al 2001; Gómez-Zeledón et al 2013; Rouxel et al 2013). There is thus a growing need to characterize and deploy mechanisms of resistance to pathogens in grapevines.…”