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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVING GRAPE ROOTSTOCK AND SCION PEST AND DISEASE RESISTANCE

Location: Grape Genetics Research

Title: Variation within and between Vitis species for foliar resistance to the powdery mildew pathogen Erysiphe necator

Authors
item Cadle-Davidson, Lance
item Consolie, Nancy
item Chicoine, D -

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 21, 2010
Publication Date: February 15, 2011
Citation: Cadle Davidson, L.E., Consolie, N.H., Chicoine, D.R. 2011. Variation within and between Vitis species for foliar resistance to the powdery mildew pathogen Erysiphe necator. Journal of Phytopathology. 95:202-211.

Interpretive Summary: To complement existing control strategies, grape growers desire cultivars with resistance to powdery mildew caused by Erysiphe necator. Numerous disease resistance screens of diverse Vitis germplasm have been conducted previously to identify powdery mildew resistance, but ratings of named cultivars were inconsistent and identities of resistant individuals in wild species were not typically provided. Inconsistencies among previous studies could be due to race-specific resistance. In the current study, controlled inoculations of a single isolate onto two leaf ages of 1025 Vitis accessions were used and the results compared to natural epidemics in two vineyards. This was exemplified by V. labrusca resistance being overcome. The data indicate that important factors for powdery mildew resistance screens are pathogen genotype(s), leaf age, and host species and accession. The results further underscore the importance to breeders of uniform testing in multiple environments.

Technical Abstract: To complement existing control strategies, grape growers desire cultivars with resistance to powdery mildew caused by Erysiphe necator. Numerous disease resistance screens of diverse Vitis germplasm have been conducted previously to identify powdery mildew resistance, but ratings of named cultivars were inconsistent and identities of resistant individuals in wild species were not typically provided. Inconsistencies among previous studies could be due to race-specific resistance. In the current study, controlled inoculations of a single isolate onto two leaf ages of 1025 Vitis accessions were used and the results compared to natural epidemics in two vineyards: the cold-hardy Vitis repository in Geneva, NY, in 2007-2008, and a five-fold replicated vineyard of 81 Vitis accessions in 2006-2008 in Fredonia, NY. Of the genotypes screened using both natural infection and single-isolate inoculation, 31.9% were resistant to a single isolate, but susceptible to diverse isolates in either or both vineyards, demonstrating race-specific resistance. This was exemplified by adaptation to V. labrusca in Fredonia, surrounded by production of the interspecific labrusca hybrids Concord and Niagara. Otherwise, there was good correlation of ratings between the vineyard and single isolate ratings (r = 0.55-0.56), and between Geneva and Fredonia vineyard ratings (r = 0.75). No accession rated in all three screens was immune from infection. While individual accessions of V. aestivalis, V. palmata, V. x doaniana, and Ampelopsis brevipedunculata were resistant in Geneva and Fredonia, each well-represented species had notable intraspecific variation in resistance. For 129 interspecific hybrids in this and previous studies, ratings infrequently corresponded among previous studies (38.6%) and between the current and previous studies (16.7-46.3%). These results highlight important factors for powdery mildew resistance screens: pathogen genotype(s), leaf age, and host species and accession. The results further underscore the importance to breeders of uniform testing in multiple environments.

Last Modified: 4/20/2014
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