Cornelius van Leeuwen

Combining ecophysiological models and genetic analysis: a promising way to dissect complex adaptive traits in grapevine

*Corresponding author : philippe.vivin@inra.fr Designing genotypes with acceptable performance under warmer or drier environments is essential for sustainable crop production in view of climate change. However, this objective is not trivial for grapevine since traits targeted for genetic improvement are complex and result from many interactions and trade-off between various physiological and molecular processes that are controlled by many environmental conditions. Integrative tools can help to understand and unravel these Genotype × Environment interactions. Indeed, models integrating physiological processes and their genetic control have been shown to provide a relevant framework for analyzing genetic diversity of complex traits and enhancing progress in plant breeding for various environments. Here we provide an overview of the work conducted by the French LACCAVE research consortium on this topic. Modeling abiotic stress tolerance and fruit quality in grapevine is a challenging issue, but it will provide the first step to design and test in silico plants better adapted to future issues of viticulture.

Hierarchy of Factors Impacting Grape Berry Mass. Separation of Direct and Indirect Effects on Major Berry Metabolites

Final berry mass, a major quality factor in wine production, is determined by the integrated effect of biotic and abiotic factors that can also influence berry composition. Under field conditions, interactions between these factors complicate study of the variability of berry mass and composition. Depending on the observation scale, the hierarchy of the impact degree of these factors can vary. The present work examines the simultaneous effects of the major factors influencing berry mass and composition to create a hierarchy by impact degree. A second objective was to separate the possible direct effects of factors on berry composition from an indirect effect mediated through their impact on berry mass. Vine water and nitrogen status of six blocks of Cabernet franc vines planted on sandy or gravelly soils were monitored over two years. Berries were analyzed from veraison to harvest. At each sampling date, fresh berry mass, berry seed mass and number, sugar content and concentration, and malic acid concentration were recorded. All studied factors significantly impacted final berry mass, but vine water status had the largest effect. The interaction between factors sometimes hid significant effects on berry compounds. Nevertheless, we showed by means of appropriate statistics that all factors had a direct impact on berry sugar and malic acid concentrations, although their order of impact varied with the metabolites considered. Conversely, the effect of factors significantly impacting berry sugar content is mediated through their impact on fresh berry mass.