Carrot resistance against Alternaria leaf blight: potential involvement of terpenes and flavonoids

International audience; Alternaria leaf blight (ALB), caused by the fungus Alternaria dauci (A. dauci), is the most damaging foliar disease affecting carrot (Daucus carota subsp. sativus). Some evidences support the potential involvement of specialized metabolites such as falcarindiol (Lecomte et al., 2012) in the resistance against ALB. In our study, we investigated the specialized metabolite composition of carrot leaf in different environments (fields and tunnel) following A. dauci infection, by comparing four carrot genotypes with different resistance levels. We identified discriminating specialized metabolites belonging to the terpene and flavonoid families, whose differential accumulation levels among genotypes correlated with their resistance. Then, we performed a bulk segregant analysis on F3 progenies to investigate the hypothesis that the discriminating terpenes and flavonoids could be linked to resistance. This study shed light on specific terpenes and flavonoids as good candidates for resistance to ALB.