Molecular Markers of Susceptible to Plasmopara viticola Genes in Grapes

Excluding offspring susceptible to grape downy mildew at an early stage could be of great value to the breeder concerned with the development of resistant grapes.BSA(Bulk segregant analysis),RAPD (randomly amplified polymorphic DNA) and SCAR (sequence characterized amplified region)were used to identify molecular genetic markers linked to downy mildew susceptibility.Two interspecific crosses [ V.quinquangularis (resistant)× V.vinifera (susceptible)]88-110 and 88-84 were analyzed.Three F 2 progenies resulting from three crosses of self cross and inter cross of 88-110 F 1 seedlings,as well as cultivars of V.vinifera and the wild grapes native to China were chosen for test too.A total of 280 arbitrary decamer oligonucleotide primers were used for RAPD analysis.Primer OPO10 produced one RAPD marker OPO10-800 tightly linked to a major downy mildew susceptible gene.Subsequently,amplified RAPD fragment OPO10 800 was cloned and sequenced.The length of OPO10 800 was 835 bp.So OPO10 800 marked into OPO10 835.The sequence was then used to design flanking 26 and 28 mer oligonucleotide SCAR primers.The primers amplified a single about 800 bp fragment,the same size as the cloned RAPD fragment.RAPD marker was converted into SCAR marker SCO10 835.The RAPD and SCAR markers were found to be applicable to other grape germplasm studied.SCAR marker SCO10 835 could be used for scoring resistant and susceptible progeny in the hybrid population and will be potentially useful in the development of new resistant grape cultivars.