title: Comparison of carotenoid accumulation and biosynthetic gene expression between Valencia and Rohde Red Valencia sweet oranges.
abstract: Carotenoid accumulation and biosynthetic gene expression levels during fruit maturation were compared between ordinary Valencia (VAL) and its more deeply colored mutant Rohde Red Valencia orange (RRV). The two cultivars exhibited different carotenoid profiles and regulatory mechanisms in flavedo and juice sacs, respectively. In flavedo, there was uncoordinated carotenoid accumulation and gene expression in RRV during green stages, which might be related to the expression of certain gene(s) in the MEP (methylerythritol phosphate) pathway. The carotenoid biosynthesis pathway shifting from α,β-xanthophylls to β,β-xanthophylls synthesis occurred in RRV earlier than VAL during orange stages. In juice sacs, the low carotenoid content in both cultivars coincided with low expression of LCYE-Contig03 and LCYE-Contig24 during green stages, suggesting LCYE might be a limiting step for carotenoid accumulation. VAL mainly accumulated violaxanthin, but RRV accumulated β-cryptoxanthin and violaxanthin during orange stages, which corresponded to differences in juice color. Several upstream genes (PDS-Contig17, LCYB-Contig19, and ZDS members) and a downstream gene (ZEP) were expressed at higher levels in RRV than VAL, which might be responsible for greater accumulation of β-cryptoxanthin and violaxanthin in RRV, respectively.
authors.affiliation: University of Florida, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850, USA; Southwest University, College of Horticulture and Landscape, 2 Tiansheng Road, Beibei District, Chongqing 400715, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Wei
authors.affiliation: USDA, ARS, Southeastern Fruit and Tree Nut Research Laboratory, 21 Dunbar Road, Byron, GA 31008, USA.
authors.forename: Chunxian
authors.initials: C
authors.lastname: Chen
authors.affiliation: University of Florida, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850, USA.
authors.forename: Qibin
authors.initials: Q
authors.lastname: Yu
authors.affiliation: University of Florida, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850, USA.
authors.forename: Antoine
authors.initials: A
authors.lastname: Gady
authors.affiliation: University of Florida, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850, USA.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Southwest University, College of Horticulture and Landscape, 2 Tiansheng Road, Beibei District, Chongqing 400715, China.
authors.forename: Guolu
authors.initials: G
authors.lastname: Liang
authors.affiliation: University of Florida, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850, USA. Electronic address: fgmitter@ufl.edu.
authors.forename: Frederick G
authors.initials: FG
authors.lastname: Gmitter
mesh_terms: D002338:Carotenoids / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D032084:Citrus sinensis / Q000145:classification / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D065366:Cryptoxanthins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D005638:Fruit / Q000254:growth & development / Q000378:metabolism*; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006801:Humans; D010940:Plant Proteins / Q000235:genetics*; D013045:Species Specificity; D024341:Xanthophylls / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism
chemical_list: D065366:Cryptoxanthins; D010940:Plant Proteins; D024341:Xanthophylls; D002338:Carotenoids; C005613:violaxanthin
keywords: Carotenoid biosynthesis pathway; Citrus; Fruit maturity; Violaxanthin; β-Cryptoxanthin