High-density genetic linkage map construction and white rot resistance QTL mapping for Vitis based on restriction site-associated DNA sequencing

Grape white rot ( Coniothyrium diplodiella ) is a major fungal disease affecting grape yield and quality. The present study aimed to provide a foundation to improve future grape white rot resistance breeding. To this end, interspecific hybridization was conducted between a white rot resistance cultivar ‘Zhuosexiang’ ( Vitus vinifera L. × Vitus labrusca L.), and a susceptible cultivar ‘Victoria’ ( Vitus vinifera L.), using 177 hybrid offspring and two parents for restriction site-associated DNA sequencing (RAD-seq) and high-density genetic linkage mapping. Female, male, and integrated map marker numbers were 2501, 4110, and 6249, respectively. The average genetic distance of adjacent markers was 1.25 cM, 0.77 cM, and 0.50 cM. White rot resistance identification of the two parents and 177 individuals was conducted in July and August of 2017 and 2018. Additionally, white rot resistance quantitative trait locus (QTL) mapping was conducted. In total, nine QTLs were detected and located on linkage groups LG1, LG4, LG7, LG12, LG14, and LG15, with overlapping QTLs on LG7 and LG15. Further, three candidate genes that may be responsible for grape white rot resistance were screened. The results will provide an important theoretical reference for future grape white rot resistance breeding.