Enhancement of Carotenoid Concentration in the Flesh of Japanese Persimmon ‘Fuyu’ by High Postharvest Temperature Treatments

Abstract

To enhance carotenoid accumulation in the flesh of Japanese persimmons by postharvest treatment, the concentration of carotenoids and the expression of carotenoid biosynthetic genes were investigated at different storage temperatures, 25°C, 10°C and room temperature (about 15.6°C). At 25°C, the concentrations increased not only in carotenes (lycopene, β-carotene and α-carotene), which were synthesized upstream to the carotenoid biosynthetic pathway, but also in xanthophylls (β-cryptoxanthin, zeaxanthin and lutein), which were synthesized downstream to the pathway, Especially in β-cryptoxanthin, the increase was remarkable. The gene expression of lycopene β-cyclase (DK-LCYb) and β-ring hydroxylase (DK-HYb), which are related to synthesis of β-cryptoxanthin and its precursor (β-carotene), was higher at 25°C than at other temperatures. These results suggested that the storage temperature at 25°C was good for carotenoid accumulation. However, at 10°C, the massive increase was observed only in the carotene concentration, especially in lycopene concentration. During 10°C storage, the decrease in gene expression of phytoene synthase (DK-PSY) and ζ-carotene desaturase (DK-ZDS), which are related to synthesis of phytoene and lycopene, was small, although, the gene expression of DK-LCYb and DK-HYb decreased strikingly. At room temperature, carotenoid concentrations and gene expressions were between those at 25°C and 10°C.