title: Tissue differential expression of lycopene beta-cyclase gene in papaya.
abstract: Carotene pigments in flowers and fruits are distinct features related to fitness advantages such as attracting insects for pollination and birds for seed dispersal. In papaya, the flesh color of the fruit is considered a quality trait that correlates with nutritional value and is linked to shelf-life of the fruit. To elucidate the carotenoid biosynthesis pathway in papaya, we took a candidate gene approach to clone the lycopene beta-cyclase gene, LCY-B. A papaya LCY-B ortholog, cpLCY-B, was successfully identified from both cDNA and bacterial artificial chromosome (BAC) libraries and complete genomic sequence was obtained from the positive BAC including the promoter region. This cpLCY-B shared 80% amino acid identity with citrus LCY-B. However, full genomic sequences from both yellow- and red-fleshed papaya were identical. Quantitative real-time PCR (qPCR) revealed similar levels of expression at six different maturing stages of fruits for both yellow- and red-fleshed genotypes. Further expression analyses of cpLCY-B showed that its expression levels were seven- and three-fold higher in leaves and, respectively, flowers than in fruits, suggesting that cpLCY-B is down-regulated during the fruit ripening process.
authors.affiliation: Hawaii Agriculture Research Center, Aiea, HI 96701, USA.
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Skelton
authors.forename: Qingyi
authors.initials: Q
authors.lastname: Yu
authors.forename: Rajeswari
authors.initials: R
authors.lastname: Srinivasan
authors.forename: Richard
authors.initials: R
authors.lastname: Manshardt
authors.forename: Paul H
authors.initials: PH
authors.lastname: Moore
authors.forename: Ray
authors.initials: R
authors.lastname: Ming
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D029441:Carica / Q000033:anatomy & histology / Q000201:enzymology* / Q000235:genetics; D002338:Carotenoids / Q000096:biosynthesis; D019753:Intramolecular Lyases / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D016415:Sequence Alignment; D014018:Tissue Distribution
chemical_list: D010940:Plant Proteins; D002338:Carotenoids; D019753:Intramolecular Lyases; C070925:lycopene cyclase-isomerase