Abstract
The viticulture industry needs advanced grape cultivars with genes that enhance disease resistance and environmental stress tolerance to meet the challenges of a changing climate. To discover beneficial allelic variants of grape genes, we established an F1 mapping population from a cross between two North American grapevines, Vitis rupestris Scheele and Vitis riparia Michx. We generated genotyping-by-sequencing (GBS) markers and constructed parental linkage maps consisting of 1177 and 1115 GBS markers, respectively (LOD threshold ≥ 14), which were validated by mapping the sex-determining locus to chromosome 2. Taking advantage of loci heterozygous in both parents, we also constructed an integrated map containing 2583 markers. We mapped a major quantitative trait locus (QTL) for downy mildew (Plasmopara viticola) resistance to chromosome 10 of V. rupestris using both greenhouse- and in vitro-generated leaf resistance data. This QTL explains 66.5% of the phenotypic variance under greenhouse conditions, and its 2-LOD confidence interval corresponds to region 2,470,297 to 3,024,940 bp on chromosome 10 in the Vitis vinifera L. PN40024 reference genome sequence (assembly 12X.v2). We provide PN40024-projected positions of the GBS markers, which can be used as anchors to develop additional markers for the introgression of this V. rupestris haplotype into cultivated grape varieties.
Highlights
The viticulture industry needs advanced grape cultivars with genes that enhance disease resistance and environmental stress tolerance to meet the challenges of a changing climate
We describe linkage map construction and quantitative trait locus (QTL) analysis in an F1 family from a cross between Vitis rupestris and Vitis riparia, two species that vary in habitat and in adaptation to different environmental conditions
GBS markers were used to examine the genetic diversity of 27 V. rupestris and 80 V. riparia accessions housed at the USDA-ARS Grape Germplasm Collection (Klein et al 2018)
Summary
The viticulture industry needs advanced grape cultivars with genes that enhance disease resistance and environmental stress tolerance to meet the challenges of a changing climate. We generated genotyping-by-sequencing (GBS) markers and constructed parental linkage maps consisting of 1177 and 1115 GBS markers, respectively (LOD threshold ≥ 14), which were validated by mapping the sex-determining locus to chromosome 2. We mapped a major quantitative trait locus (QTL) for downy mildew (Plasmopara viticola) resistance to chromosome 10 of V. rupestris using both greenhouseand in vitro-generated leaf resistance data. This QTL explains 66.5% of the phenotypic variance under greenhouse conditions, and its 2-LOD confidence interval corresponds to region 2,470,297 to 3,024,940 bp on chromosome 10 in the Vitis vinifera L. Cultivation of disease-resistant grape varieties carrying genes that enhance defense against pathogens is an approach that helps reduce the amount of fungicides applied in viticulture. The source of such defense-related genes has been the North American wild relatives of V. vinifera, as they coevolved with now-pandemic pathogens and acquired allelic diversity that strengthens resistance against fun-
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