ED Sciences de la Vie et de la Santé
Study of rootstock × scion interactions to characterize the effect of rootstock on agronomic traits of interest in grapevine
by Marine MOREL (Ecophysiologie et Génomique Fonctionnelle de la Vigne)
The defense will take place at 9h00 - Amphithéâtre Institut des Sciences de la Vigne et du Vin (ISVV) 210 Chemin de Leysotte 33140 Villenave d'Ornon
in front of the jury composed of
- Allison J. MILLER - Professeur des universités - Saint Louis University - Rapporteur
- Vincent SEGURA - Chargé de recherche - INRAE, UMR AGAP - Rapporteur
- Thierry LACOMBE - Professeur - Institut Agro Montpellier - Examinateur
- Emilie J. MILLET - Chargée de recherche - INRAE, UMR GAFL - Examinateur
Among the possible solutions for adapting vineyards to climate change and agroecological transition, the use of rootstocks that confer sufficient productivity and vigor appears to be one of the most sustainable options. This approach allows traditional grape varieties to be preserved while limiting the use of water and fertilizers. A major challenge in rootstock research is accounting for rootstock × scion interactions. This thesis aims to characterize and quantify rootstock × scion interactions for agronomic traits of interest. We first evaluated the effect of the rootstock on yield components (15% of the variance explained by the rootstock) and proposed several physiological hypotheses to explain the different responses induced by the rootstock. As rootstock effects on yield can be influenced by differences in water and mineral status, we then quantified the effects of the rootstock and scion, as well as their interaction, on mineral content in scion petioles. The effect of the rootstock was found to be greater than that of the scion for phosphorus and magnesium content. Additionally, we highlighted the significant effects of different genetic backgrounds traditionally used in crosses to develop commercial rootstocks. However, the traits themselves do not perfectly reflect responses to the environment in the broad sense, which is why we considered the plasticity of yield and vigor conferred by the rootstock across scions. A significant effect of the rootstock was shown on plasticity, described as adaptive based on its positive correlation with the maximum value of the trait considered. This work is part of grapevine rootstock breeding programs. However, it is essential to evaluate nursery traits (rooting ability and grafting success), as these are real bottlenecks to the successful deployment of rootstocks in commercial nurseries and vineyards. A complex genetic control has been identified, and candidate genes were suggested, while genotypes were proposed for use in crossing or directly as rootstocks.