South Africa Wine Research Projects

2. VITICULTURE RESEARCH NEW PROJECT

2.6 GRAPEVINE IMPROVEMENT SELECTION OF GLRaV-3 RESISTANT ROOTSTOCKS FOR THE SOUTH AFRICAN WINE INDUSTRY

PATHSOL GP 24-01 Prof Gerhard Pietersen, Patho Solutions Start date: 2024

AIM AND INDUSTRY RELEVANCE: Grapevine Leafroll-associated Virus 3 (GLRaV-3) can be transmitted to vines during the grafting process via GLRaV-3-contaminated rootstocks. It has been demonstrated that GLRaV-3 susceptible and resistant individuals exist within the Vitis rootstock selection most frequently used in South Africa. This study aims to select GLRaV-3-resistant rootstocks of the six most vital rootstock cultivars, establish them, verify their resistance, and make them widely available to the industry. The process will start with identifying sources of potentially resistant rootstocks and then selecting GLRaV-3-resistant individuals of rootstocks 101-14 Mgt, Paulsen 1103, Richter 99, Richter 110, Ruggeri 140 and US 8-7. Additional testing will ensure no other pathogens are found in these individuals, followed by establishing resistant rootstock sources in a vector-free environment. Further confirmation of the absence of GLRaV-3 will be done, followed by GLRaV-3 resistance confirmation via artificial inoculation, in which pure sources of GLRaV-3 variants will be grafted onto young plantlets from each source of the selected rootstock. The last step will be distributing the selected immune phenotype material to plant improvement organisations within the South African wine industry.

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SOUTH AFRICA WINE RESEARCH 2024