Marker-assisted pyramiding of resistance loci to grape downy mildew

Abstract: The objective of this work was to use a marker-assisted selection for pyramiding the resistance loci Rpv1 and Rpv3.1 in grapevine (Vitis vinifera), and to evaluate their conferred resistance against Brazilian downy mildew (Plasmopara viticola) isolates. A progeny of 23 plants, segregating for the two resistance loci, was obtained by the cross between the Gf 2000-305-122 and Gf.Ga-52-42 genotypes. The progeny was genotyped with four microsatellite markers and phenotyped for resistance to P. viticola using a bioassay with leaf discs. Six plants containing the Rpv1 and Rpv3.1 pyramided loci were identified by the molecular analysis. Plants harboring the Rpv1 + Rpv3.1, Rpv3.1, and Rpv1 loci showed 12.8, 30.0, and 33.1 sporangiophores per leaf disc, respectively. Plants with no resistance loci showed a dense sporulation. The phenotypic analysis of the expression of the two pyramided loci was only confirmed for four plants that showed the highest resistance level, i.e., mean value of 1.8 sporangiophores. A high-throughput method for pyramiding the Rpv1 and Rpv3.1 loci was developed, which confirmed the increased resistance to P. viticola. The selected elite genetic material shows a high resistance to downy mildew and elevated enological potential for grapevine breeding in Brazil.摘要：本研究旨在通过标记辅助选择（marker-assisted selection）聚合葡萄（Vitis vinifera）中的抗病基因座Rpv1与Rpv3.1，并评估其对巴西葡萄霜霉菌（Plasmopara viticola）分离物的抗病效果。以Gf 2000-305-122与Gf.Ga-52-42基因型为亲本杂交，获得23株分离携带这两个抗病基因座的杂交后代植株。采用4个微卫星标记（microsatellite markers）对该杂交后代进行基因分型，并通过叶盘生物测定法对其抗葡萄霜霉菌（P. viticola）性能开展表型鉴定。经分子分析，共鉴定出6株同时聚合了Rpv1与Rpv3.1基因座的植株。携带Rpv1+Rpv3.1、Rpv3.1以及Rpv1基因座的植株，每叶盘的孢囊梗（sporangiophores）数量分别为12.8、30.0和33.1。未携带任何抗病基因座的植株则表现出密集产孢。仅在4株抗病水平最高的植株中验证了两个聚合基因座的表型表达效果，其平均每叶盘孢囊梗数量仅为1.8。本研究开发了一种可高效聚合Rpv1与Rpv3.1基因座的高通量方法，证实该方法可显著提升植株对葡萄霜霉菌的抗性。筛选获得的优良遗传材料对霜霉病具有高抗性，且具备优异的酿酒潜力，可应用于巴西的葡萄育种工作。