Combined Alternaria dauci infection and water stresses impact carotenoid content of carrot leaves and roots

Abstract Carotenoids are important secondary metabolites involved in plant photosynthesis, vegetable nutritional quality but also in metabolic prevention in human health. Carrot represents one of the most important carotenoid intakes and is a very interesting model to study carotenoid metabolism. Till now, the knowledge about the impact of stress on carotenoid accumulation is limited. The purpose of this work was to investigate the impact of abiotic and biotic stresses applied separately or in combination on carotenoid accumulation in carrot leaves and roots. Results showed that combined stress decreased dramatically carotenoid content in both organs. In roots, the decrease in carotenoid content could be mostly associated in carrot response to A. dauci infection. Moreover, carotenoid and sugar contents were highly correlated, which suggests that stored metabolites are directly or indirectly involved in plant response to pathogen infection. In leaves, in contrast to results observed in roots, stresses impact carotenoid content depending on the genotype and the year. Moreover, carotenoid content variations were correlated to chlorophyll contents suggesting that a common mechanism of regulation for photosynthetic biosynthesis pigment exists.