Phenotyping for drought tolerance in grapevine populations
Résumé
Genetic studies of abiotic stress tolerance in fruit perennials require large fields where soil conditions are rarely homogenous. We examined how to consider this heterogeneity for genetic analyses of grapevine response to water stress. After a short review of available methods, we propose a case study where carbon isotope discrimination (δ13C) was characterized as a proxy for water-use efficiency in a grapevine population planted in a field subdivided into irrigated and nonirrigated blocks. Predawn leaf water potential (Ψpredawn) was measured on control plants, cv. Grenache, evenly spaced across the field. We combined correlations between δ13C and Ψpredawn drawn on these plants, with Ψpredawn values interpolated by kriging for any genotype at any location in the field, to correct δ13C raw values. Genetic analysis (QTL detection) on δ13C was improved by working with corrected values as compared to raw values, supporting the relevance of the method to correct for spatial heterogeneity.