Using functional-structural models to design architectural ideotypes of grapevine to cope with extreme heat and water...

Extreme heat combined with water stress can cause significant physiological damage, including leaf burn in grapevine (Vitis vinifera L.), highlighting the need for varieties better adapted to high temperatures. Modifying specific functional and architectural traits may help mitigate these stresses. However, the impact of genotypic variation in grapevine architecture on leaf temperature and related carbon and water traits has not been thoroughly studied. This study aimed to identify grapevine architectural ideotypes that maximize net carbon assimilation (An) and water use efficiency (WUE) while minimizing leaf temperature (Tleaf) using a functional-structural plant model (FSPM). We generated 1000 3D plant mock-ups by varying leaf area (LA), elevation angle (R), and internode length (IL), based on measurements carried out on a world-wide diversity panel of V. vinifera L. Simulations were run under hot and extremely hot conditions, combined with mild and severe water deficits. Architectural traits significantly affected An, WUE, and-to a lesser extent-Tleaf. Within a single mock-up, up to 10 °C of variation between the coldest and warmest leaves was simulated. Across all weather conditions, large LA, moderate IL, and downward leaf orientation minimized the temperature of the hottest leaves with minimal impact on An and WUE. Ideotypes for dry and hot conditions were identified by minimizing the phenotypic distance between best performing morphotypes and the diversity panel. This study highlights the potential of targeted architectural modifications to enhance grapevine resilience to climate change.