Cloning and Expression Analysis of Carotenogenic Genes during Ripening of Autumn Olive Fruit (Elaeagnus umbellata)

Abstract

Autumn olive ( Elaeagnus umbellata Thunb.) is an extremely lycopene-rich natural source, and lycopene concentration of ripe wild autumn olive fruit was 12 times higher than that of tomato. Lycopene formation was found to increase with significant reduction of other carotenoids and chlorophylls during fruit ripening. To elucidate the molecular basis of massive lycopene accumulation in autumn olive fruit, seven cDNA fragments were cloned encoding enzymes of the main steps of carotenoid biosynthetic pathway, which were geranylgeranyl pyrophosphate synthase (EutGgps), phytoene synthase (EutPsy), phytoene desaturase (EutPds), zeta-carotene desaturase (EutZds), lycopene beta-cyclase (EutLcy-b), lycopene epsilon-cyclase (EutLcy-e), and beta-carotene hydroxylase (EutBch). The accumulation of lycopene in the fruit was concomitant with the up-regulation of upstream genes of lycopene synthesis (EutGgps, EutPsy, EutPds, and EutZds) and down-regulation of downstream genes (EutLcy-b and EutBch) and in particular with the silence of EutLcy-e throughout fruit ripening. Thus, lycopene accumulation in autumn olive fruit was highly regulated by the coordination of the expression among carotenogenic genes and by fruit ripening.