Tissue-specific elucidation of lycopene metabolism in commercial tomato fruit cultivars during ripening

Lycopene is a naturally occurring chemical compound that gives fruits and vegetables a red/orange color. As an intermediate metabolite of β-carotene biosynthesis, lycopene represents one of the major carotenoids. This work studies the gene expression pattern of lycopene biosynthesis/catabolism transcripts and the accumulation pattern of lycopene/β-carotene/chlorophyll contents at three developmental stages and three tissues in five widely consumed, commercial tomato cultivars (cvs. ‘Cherry Ninolino F1’, ‘Elpida F1’, ‘Daphne F1’, ‘Eliseo Plum F1’, and ‘Oxheart’). These contents were correlated with in vitro antioxidant activity. Higher levels of lycopene were observed in the peel than other tissues and in the fully ripe stage, with ‘Oxheart’ displaying the highest content. Differential regulation of lycopene biosynthetic genes (SlZDS and SlCRTISO) was demonstrated in all cultivars. Interestingly, a gene implicated in lycopene catabolism (SlLCYB) demonstrated a general induction in the tested tissues. High lycopene content correlates with significant induction of both SlZDS and SlCRTISO in ‘Oxheart’. Significantly increased antioxidant activity was observed in the peel of ‘Cherry Ninolino F1’ and ‘Elpida F1’ cultivars compared with other tested tissues across all cultivars. The exploration of lycopene activity in different cultivars and the consumption of ripe tomatoes including the peel could be useful for the protection of human health.