title: Identification of genes associated with low furanocoumarin content in grapefruit.
abstract: Some furanocoumarins in grapefruit (Citrus paradisi) are associated with the so-called grapefruit juice effect. Previous phytochemical quantification and genetic analysis suggested that the synthesis of these furanocoumarins may be controlled by a single gene in the pathway. In this study, cDNA-amplified fragment length polymorphism (cDNA-AFLP) analysis of fruit tissues was performed to identify the candidate gene(s) likely associated with low furanocoumarin content in grapefruit. Fifteen tentative differentially expressed fragments were cloned through the cDNA-AFLP analysis of the grapefruit variety Foster and its spontaneous low-furanocoumarin mutant Low Acid Foster. Sequence analysis revealed a cDNA-AFLP fragment, Contig 6, was homologous to a substrate-proved psoralen synthase gene, CYP71A22, and was part of citrus unigenes Cit.3003 and Csi.1332, and predicted genes Ciclev10004717m in mandarin and orange1.1g041507m in sweet orange. The two predicted genes contained the highly conserved motifs at one of the substrate recognition sites of CYP71A22. Digital gene expression profile showed the unigenes were expressed only in fruit and seed. Quantitative real-time PCR also proved Contig 6 was down-regulated in Low Acid Foster. These results showed the differentially expressed Contig 6 was related to the reduced furanocoumarin levels in the mutant. The identified fragment, homologs, unigenes, and genes may facilitate further furanocoumarin genetic study and grapefruit variety improvement.
authors.affiliation: University of Florida, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850, USA., United States Department of Agriculture, Agricultural Research Service, Southeastern Fruit and Tree Nut Research Laboratory, 21 Dunbar Road, Byron, GA 31008, USA.
authors.forename: Chunxian
authors.initials: C
authors.lastname: Chen
authors.forename: Qibin
authors.initials: Q
authors.lastname: Yu
authors.forename: Xu
authors.initials: X
authors.lastname: Wei
authors.forename: Paul F
authors.initials: PF
authors.lastname: Cancalon
authors.forename: Fred G
authors.initials: FG
authors.lastname: Gmitter
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D032083:Citrus paradisi / Q000235:genetics*; D003001:Cloning, Molecular; D005638:Fruit / Q000235:genetics; D011564:Furocoumarins / Q000096:biosynthesis*; D017343:Genes, Plant; D023281:Genomics; D058977:Molecular Sequence Annotation
chemical_list: D011564:Furocoumarins
keywords: Citrus paradisi; differential expression; effet du jus de pamplemousse; expression différentielle; grapefruit juice effect; psoralen synthase; psoralène synthase