Primary Studies On Carotenoid Accumulation In Loquat Fruit

The amounts of carotenoids in pulp of cultivars of'Daohongpao'and'Qingzhong'that belong to two different loquat types were determined ; and the changes of plasmid ultra-structure were observed during fruit coloring; as well as two fragments of carotenoid biosynthesize gene, Lycopene-β- cyclase gene andβ-carotene hydroxylase gene, were cloned. The results were as follows:(1) Lutein content of pulp decreased rapidly at first and then rose a little, being accompanied by a gradual increase in amounts of the other 4 carotenoid compositions early, and rapid rise 7 days before maturation. The amounts inα-carotene andβ-carotene were the major carotenoids affecting color levels between'Daohongpao'and'Qingzhong',while the amounts in xanthphylls played a little role in those of total carotenoids.(2) From ultra-structure angle, the plasmid in peel changed at each stage of fruit development. At green stage, the structure of chloroplast was completely well, characterized with a typical granum-granum thylakoid structure. At yellow-green stage, chloroplast disintegrated generally, didn't have the typical structure of chloroplast any more; At yellow and orange stage, the ball in plasmid increase gradually, correspondingly, the lipid content were raised , which provided a base for caroteniod accumulation in the plasmid.(3)A pair of primer, designed from conserved regions of lycopeneβ-cyclase gene of rose family, was used to amplify homologous gene by polymerase chain reaction (PCR). As a result, one fragment about 300 bp was obtained, and then cloned into pMD-18T vector and sequenced. The result showed that the 310 bp belonged to a part of ORF (Open Reading frame) with the code of 102 amino acids. It was suggested that the sequence was 97 % identical to the lycopene-β-cyclase gene from apple. Therefore, it could be deduced as lycopene-β-cyclase gene fragment of loquat.(4)A pair of primer, designed from conserved regions ofβ-carotene hydroxylase from rosaceae, was used to amplify homogeneous gene by polymerase chain reaction (PCR). As a result, one about 450bp fragment was obtained, and then cloned into pMD-18T vector and sequenced. The result suggested that the 440bp belong to a part of ORF (Open Reading Frame) and encode 145 amino acids. It is suggested that the sequence is 95% identical to theβ-carotene hydroxylase gene from apple; it could be deduced asβ-carotene hydroxylase gene fragment of loquat.