South Africa Wine Research Projects

2. VITICULTURE RESEARCH NEW PROJECT

GENOMIC COMPARISON OF RAMSEY GLRaV-3 IMMUNE AND SUSCEPTIBLE SOURCES

PATHSOL GP 24-03 Prof Gerhard Pietersen, Patho Solutions Project is co-funded by SF & VR du Toit Studiefondstrust Start date: 2024

AIM AND INDUSTRY RELEVANCE: Recent, ongoing research has revealed GLRaV-3 susceptible, tolerant and immune phenotypes in Ramsey ( Vitis champinii ) sources. The reason for these differences is unknown. This project aims to compare the genomes of the different phenotypes on a molecular level in an attempt to find the underlying cause. A detailed genetic and genomic comparison between resistant and susceptible near-isogenic Ramsey individuals may lead to identifying the potential gene(s) underlying the resistance. This knowledge creates the possibility of incorporating leafroll resistance into not only other rootstocks but also into scions and to understand the virus’s mode of infection better. Vitis champinii is also a recognised stress-tolerant Vitis species, and the characterisation of its genome will also be of value in endeavours to identify further drought-tolerant vines. The project has five objectives: • Identify near-isogenic Ramsey material that shows a range of resistance to leafroll - susceptible, tolerant and immune. • Perform phased diploid genome sequencing on immune and susceptible material. • Assemble diploid genomes of the immune and susceptible clones. • Perform transcriptome analysis on immune and susceptible clones. • Screen assembled genome data and transcriptome data for functional sequence variations potentially underlying the resistance/susceptibility trait. The project has received support and positive feedback from industry organisations and wineries, highlighting the importance of finding solutions to combat the leafroll virus in the wine industry.

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SOUTH AFRICA WINE RESEARCH 2024