Abstract
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.
Highlights
Brazilian viticulture occupies an area of approximately 69,096 ha, with a production of approximately 1.23 million tons of grapes (IBGE, 2016)
The plants that had the two combined resistance alleles had an average of 12.8 sporangiophores per leaf disc, while plants that had only one of the resistance alleles showed a mean of 31.5 sporangiophores (Table 1)
Plants without the presence of any of the resistance loci were highly susceptible to the pathogen and displayed dense sporulation, making it difficult to count the sporangiophores
Summary
Brazilian viticulture occupies an area of approximately 69,096 ha, with a production of approximately 1.23 million tons of grapes (IBGE, 2016). In 2016, the State reported a production of approximately 186.4 million liters of wine. Out of this total production, 19.6 million (10.5%) liters were produced from European grapevine varieties (Vitis vinifera), and the rest came from American and hybrid varieties (Uvibra, 2016). The management of downy mildew is only possible by preventive, massive applications of several fungicides (Czermainski & Sônego, 2004; Pereira et al, 2010). This increases the production costs, as well as the risks to human health and to the environment. The development of new cultivars, with high genetic resistance to downy mildew and high enological quality, is essential to promote the sustainability of Brazilian viticulture
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