The ripening influence of two papaya cultivars on carotenoid biosynthesis and radical scavenging capacity

• The all-trans-β-cryptoxanthin levels increased 18-fold during ripening in the Sunrise Solo.
• Gene's expression during ripening and levels of carotenoids in papaya were correlated.
• Carotenoid accumulation was not followed by an increase of antioxidant capacity.

Carotenoid biosynthesis in papaya fruits from the cultivars (cv.) ‘Golden’ and ‘Sunrise Solo’ was studied throughout three different ripening stages. The content of these secondary metabolites was assessed using HPLC–PDA–MSn. Carotenoid levels increased during ripening, with all-trans-lycopene varying from 0.73 to 1.58 μg/g in the cv. ‘Golden’ and from 0.68 to 1.67 μg/g in the cv. ‘Sunrise Solo’. The all-trans-β-cryptoxanthin content varied from 1.29 to 3.0 μg/g in the cv. ‘Golden’ and from 0.28 to 5.13 μg/g in the cv. ‘Sunrise Solo’. The Zds gene showed a different pattern of expression during the ripening and between cultivars, while the Lcyβ gene expression was up-regulated in the two cultivars. The capacity to scavenge peroxyl radicals did not show a significant difference among the ripening stages and between the different cultivars. This study describes, for the first time, a tentative correlation between carotenoid biosynthesis in papaya pulp and the gene expression of the enzymes related to this pathway.