Carotenoid Composition And Cloning And Expression Analysis Of Carotenogenic Genes During Ripening Of Autumn Olive Fruit (Elaeagnus Umbellata Thunb.)

Lycopene, a red linear carotenoid and an isomer of fat-soluble carotene with 11 conjugated double-bonds and two non-conjugated double-bonds, is the most potent antioxidant from plant sources and exhibits the highest physical quenching rate constant with singlet oxygen. Lycopene could reduce the risk of chronic diseases such as cardiovascular diseases and different forms of cancer, and inhibite the growth of human colon cancer cells even at low concentration. Due to the important role of lycopene in human health, consumer demand for lycopene-rich food and nutraceutical products is growing. Therefore, the development for new idioplasm resources of lycopene was very significant. Heredity breeding, especially regulating lycopene biosynthesis and modifying tomato variety or other industrial crops to rich source of lycopene with transgenic method is useful.By far the most promising is autumn olive fruit, in which the lycopene is about 17 times higher than that of tomato, and reaches up about 75 mg/100 g fresh weight. The pathway of carotenoid biosynthesis in higher plants is illustrated. Carotenoid biosynthesis and its regulation have been studied in various plant species. But little is still known about the molecular mechanism of lycopene biosynthesis in autumn olive fruit. In this case, we cloned seven carotenogenic genes Ggps, Psy, Pds, Zds, Lcy-b, Lcy-e, Bch, and two control genes Gapdh and Actin from autumn olive. All of these carotenogenic genes were evaluated at transcript level in order to determine which of them played a major role in massive lycopene accumulation during fruit ripening. Characterization of the full-length Pds was also studied. The results are as follows:â‘ The lycopene accumulation in autumn olive fruit was highly regulated by the coordination of the expression among carotenogenic genes. The massive lycopene accumulation in autumn olive fruit was concomitant with the up-regulation of upstream genes of lycopene synthesis (Ggps, Psy, Pds and Zds), and down-regulation of downstream genes (Lcy-b and Bch), and in particular with the silence of Lcy-e throughout fruit ripening.â‘¡The formation of lutein was feasible before stage A. The level of lutein decreased progressively from stage A to stage D probably due to a dilution effect caused by the enlargement of the fruit. This theory can be used to explain the presence of lutein though Lcy-e is silent.â‘¢The full-length cDNA of Pds contains an ORF of 1749 bp encoding a polypeptide of 582 amino acids, and was not interrupted by any intron. In silico analysis of the predicted amino acid sequence showed a pI of 8.12 and molecular mass of 65.2 kD.â‘£The genomic DNA of autumn olive contains a single copy of Pds and Psy.