Carotenoid content in mature tomato fruit under soil water deficit: accounting the role of pre-maturing processes through chlorophyll kinetics and cell microscopy

International audience

Английский. Soil water deficit triggers a wide range of plant responses that interact with the initiation, development and maturation of reproductive organs. In the case of fleshy fruits that are part of human diet, those processes may interact with the accumulation of micronutrients in the fruit tissue. As precursors of vitamins or anti-oxidants, those micronutrients and more precisely the family of carotenoids, play a determinant role in human health. Carotenoid distributed in fruit tissue are produced and stored in plastid endosymbiotic organelles. For the green fruit, most plastids are green pigmented chloroplasts rich in chlorophyll. During the maturation process, the majority of chloroplasts are converted into to carotenoid rich, red-pigmented chromoplasts. Our study provides the dynamics of chlorophyll and carotenoid contents in tomato fruit sampled at six development stages: from 5 days post anthesis to 60 days post anthesis under four different water regimes. Biochemistry analyses of fruits have been supplemented by microscopy data to assess the weight of pre-maturation profile (pigment fluorescence, chlorophyll content) in the mature fruit carotenoid content. Deficit irrigation from fruit set to fruit harvest statistically increased chlorophyll load on green fruits by +23% and total mature fruit carotenoid content by +18% on a fresh matter basis. Pigment fluorescence reveals pericarp fruit tissue plastid content is concentrated into hotspots suggesting relevance to target specific tissue regions to explain changes in mature fruit carotenoid content. This work contributes to characterize fruit health potential submitted to climatic drought or water-scarce irrigation policy.