Resistance to Plasmopara viticola in grapevine 'Bianca' is controlled by a major dominant gene causing localised necrosis at the infection site.

摘要: Downy mildew resistance is a quantitative trait in grapevines of the genus Vitis. The grapevine ‘Bianca’ has retained resistance, originally present its North American ancestors, through several cycles backcrossing with susceptible cultivars Vitis vinifera followed by phenotypic selection. genetic control was studied using 116 full-siblings from cross ‘Chardonnay’ × and parental maps consisting 298 312 markers, respectively. Ratings histological identification stage interaction, when pathogen development impaired resistant individuals, were performed leaf disc inoculation assays two isolates Plasmopara viticola collected Italian French vineyards. 59% offspring heterozygous for dominant gene, located 2.9 cM interval at Rpv3 locus on chromosome 18, responsible onset hypersensitive response (HR) infection sites within 2 days post (dpi). Localised necrosis earliest difference compared to it did not halt growth, but associated significant reduction performance disease symptoms 3 6 dpi. QTL peaks ratings revealed strongest effects being caused locus: extent mesophyll colonisation (LOD 3.1, percentage explained variance 16.2%), sporulation density (29.7, 74.3%), symptom severity expressed OIV452 descriptor recommended Office International de la Vigne et du Vin (28.3, 74.6%). Strong correlation observed between ability seedling mount an HR under controlled experimental conditions adult plant exposed natural infections field, which number leaves fungal sporulation, consecutive years observations.