Phenotyping the response of sunflower (Helianthus annuus L.) to drought scenarios in multi-environmental trials for the purpose of association genetics

In a context of global climatic change, improving yield in drought conditions is a major challenge for crop production sustainability. Most of the previous genetic studies on sunflower response to drought have been performed on a limited number of genotypes in controlled conditions, or were based on phenotypic per se responses of recombinant inbred lines. In contrast, we evaluated in testcross a panel of 384 sunflower lines across a multi-environmental trials (MET) including 17 years * locations combinations. We used the crop model SUNFLO to estimate a drought stress index in each environment through the response of previously characterized probe genotypes. The panel response to such a stress index has been the target of a genome-wide association analysis. Due to the short extent of linkage disequilibrium in sunflower, requiring high number of SNP markers for good genome coverage, we combined to the identification of thousands of loci distributed across the genome, SNP polymorphisms on sunflower candidate genes being homologous to Arabidopsis genes shown as involved in drought stress signalling or response. These two strategies led to the genotyping of 10 000 SNP currently tested for association with the phenotype.

This work was supported by the French ANR, the French public funds for competitiveness clusters, (FUI), the European EFDR, the Région Midi Pyrénées, the Departmental Board of Aveyron (France), and the Cities Cluster of Rodez (France).