摘要
Carotenoid cleavage dioxygenases (CCDs) are a class of enzymes in plants involved in the biosynthesis of apocarotenoids, such as phytohormones, flavour compounds, and other compounds with yet unknown functions. To date, several CCDs have been functionally characterised in plants, but little is known about the CCD4 members. A carotenoid cleavage dioxygenase 4 gene (LcCCD4) was isolated from the leaves of wolfberry (Lycium chinense) to gain insight into its biological function. Multiple sequence alignment and phylogenetic analyses showed that the deduced amino acid sequence of LcCCD4 shares high homology with that of CCD4 proteins from other plants. Expression analysis using semi-quantitative polymerase chain reaction revealed that LcCCD4 was strongly expressed in leaves and flowers and that the expression level was in accordance with β-carotene concentration. LcCCD4 transcripts in fruits tended to decrease as carotenoids accumulated. Recombinant expression of LcCCD4 cleaved β-carotene to produce β-ionone in in vivo assays. These results show that LcCCD4 is a CCD gene that may be involved in producing aromatic apocarotenoids in leaves and flowers, whereas it may be involved in controlling carotenoid accumulation in fruits. © 2016, Tianjin University and Springer-Verlag Berlin Heidelberg.
Carotenoid cleavage dioxygenases(CCDs) are a class of enzymes in plants involved in the biosynthesis of apocarotenoids,such as phytohormones,flavour compounds,and other compounds with yet unknown functions.To date,several CCDs have been functionally characterised in plants,but little is known about the CCD4 members.A carotenoid cleavage dioxygenase 4 gene(LcCCD4) was isolated from the leaves of wolfberry(Lycium chinense) to gain insight into its biological function.Multiple sequence alignment and phylogenetic analyses showed that the deduced amino acid sequence of LcCCD4 shares high homology with that of CCD4 proteins from other plants.Expression analysis using semi-quantitative polymerase chain reaction revealed that LcCCD4 was strongly expressed in leaves and flowers and that the expression level was in accordance with β-carotene concentration.LcCCD4 transcripts in fruits tended to decrease as carotenoids accumulated.Recombinant expression of LcCCD4 cleaved β-carotene to produce P-ionone in in vivo assays.These results show that LcCCD4 is a CCD gene that may be involved in producing aromatic apocarotenoids in leaves and flowers,whereas it may be involved in controlling carotenoid accumulation in fruits.
基金
Supported by the National Natural Science Foundation of China (No.31271419 and No.31300329)
