Identification of molecular genetic markers tightly linked to downy mildew resistant genes in grape.

Bulk segregant analysis (BSA), randomly amplified polymorphic DNA (RAPD) and sequence characterized amplified region (SCAR) methods were used to tag the downy mildew-resistant genes of grape with molecular markers. Parents and their 60 individuals of an F1 progeny resulting from a cross 88-110 between 83-4-96 (Vitis quinquangularis, downy mildew-resistant) and Muscat Rose (V. vinifera, downy mildew-susceptible), three F2 progenies resulting from three crosses of self-cross and inter-cross of 88-110 F1 seedlings, as well as another interspecific F1 hybrids of 88-84 cross [Xun-3 (V. quinquangularis, downy mildew-resistant) x Ugni Blanc (V. vinifera, downy mildew-susceptible)] and the wild grapes native to China were used for the study. Among 280 Operon primers, 160 gave distinct band patterns. One RAPD marker OPO06-1500 was tightly linked to a major gene resistant to Plasmopara viticola (RPv-1). Based on Mapmaker software analysis, the map distance between RPv-1 and OPO06-1500 was 1.7 cM. Marker OPO06-1500 was cloned and sequenced. According to the sequence, two specific primers were designed to amplify all plant materials. RAPD marker was converted into SCAR marker (SCO06-1500). One distinct single band only in resistant plants was amplified, whose size was the same as that of the RAPD marker. The SCAR marker's popularity was confirmed, and it could be used for the identification of hybrid resistant to P. viticola and will be potentially useful in the development of new resistant grape cultivars.