Characterization and developmental expression of genes encoding the early carotenoid biosynthetic enzymes in Citrus paradisi Macf

• Published in: Molecular biology reports Vol. 39; no. 2; pp. 895 - 902
• Main Authors: Costa, Marcio G. C., Moreira, Cristina D., Melton, John R., Otoni, Wagner C., Moore, Gloria A.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-02-2012; Springer Nature B.V
• Subjects: Abundance; Albedo; Amino Acid Sequence; Amino acids; Animal Anatomy; Animal Biochemistry; Arabidopsis; Base Sequence; Biomedical and Life Sciences; Biosynthesis; Biosynthetic Pathways - genetics; Carotenoids; Carotenoids - biosynthesis; Chromatophores; Citrus fruits; Citrus paradisi; Citrus paradisi - enzymology; Cloning, Molecular; Color; Computational Biology; Data processing; Developmental stages; DNA Primers - genetics; Enzymes; Enzymes - genetics; Enzymes - metabolism; Evolution; Fruits; Gene Components - genetics; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Plant - genetics; Histology; Homology; Juices; Life Sciences; lycopene; Lycopersicon esculentum; Molecular biology; Molecular Sequence Data; Morphology; Open reading frames; Open Reading Frames - genetics; Phylogeny; Polypeptides; Ripening; Sequence Analysis, DNA; Transcription; Vesicles; Grapefruit; Regulation; Phytoene desaturase; Gene expression; Phytoene synthase; Zeta-carotene desaturase
• ISSN: 0301-4851; 1573-4978
• DOI: 10.1007/s11033-011-0814-2

In the present study, the full-length cDNA sequences of
PSY
,
PDS
, and
ZDS
, encoding the early carotenoid biosynthetic enzymes in the carotenoid pathway of grapefruit (
Citrus paradisi
), were isolated and characterized for the first time.
CpPSY
contained a 1311-bp open reading frame (ORF) encoding a polypeptide of 436 amino acids,
CpPDS
contained a 1659-bp ORF encoding a polypeptide of 552 amino acids, and
CpZDS
contained a 1713-bp ORF encoding a polypeptide of 570 amino acids. Phylogenetic analysis indicated that CpPSY shares homology with PSYs from
Citrus
, tomato, pepper,
Arabidopsis
, and the monocot PSY1 group, while CpPDS and CpZDS are most closely related to orthologs from
Citrus
and tomato. Expression analysis revealed fluctuations in
CpPSY
,
CpPDS
, and
CpZDS
transcript abundance and a non-coordinated regulation between the former and the two latter genes during fruit development in albedo and juice vesicles of white (‘Duncan’) and red (‘Flame’) grapefruits. A 3× higher upregulation of
CpPSY
expression in juice vesicles of red-fleshed ‘Flame’ as compared to white-fruited ‘Duncan’ was observed in the middle stages of fruit development, which correlates with the well documented accumulation pattern of lycopene in red grapefruit. Together with previous data, our results suggest that the primary mechanism controlling lycopene accumulation in red grapefruit involves the transcriptional upregulation of
CpPSY
, which controls the flux into the carotenoid pathway, and the downregulated expression of
CpLCYB2
, which controls the step of cyclization of lycopene in chromoplasts during fruit ripening. A correlation between
CpPSY
expression and fruit color evolution in red grapefruit is demonstrated.