RT Journal Article SR Electronic T1 A Novel Grape Downy Mildew Resistance Locus from Vitis rupestris JF American Journal of Enology and Viticulture JO Am J Enol Vitic. FD American Society for Enology and Viticulture SP 12 OP 20 DO 10.5344/ajev.2020.20030 VO 72 IS 1 A1 Gaurab Bhattarai A1 Anne Fennell A1 Jason P. Londo A1 Courtney Coleman A1 Laszlo G. Kovacs YR 2021 UL http://www.ajevonline.org/content/72/1/12.abstract AB 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.