TY - JOUR T1 - A Novel Grape Downy Mildew Resistance Locus from <em>Vitis rupestris</em> JF - American Journal of Enology and Viticulture JO - Am J Enol Vitic. SP - 12 LP - 20 DO - 10.5344/ajev.2020.20030 VL - 72 IS - 1 AU - Gaurab Bhattarai AU - Anne Fennell AU - Jason P. Londo AU - Courtney Coleman AU - Laszlo G. Kovacs Y1 - 2021/01/01 UR - http://www.ajevonline.org/content/72/1/12.abstract N2 - 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. ER -