title: RNA interference-based gene silencing of phytoene synthase impairs growth, carotenoids, and plastid phenotype in Oncidium hybrid orchid.
abstract: Phytoene synthase (PSY) is the first rate-limiting regulatory enzyme in the carotenoid biosynthesis pathway. In order to modify the floral color pattern by reducing carotenoid contents, a phytoene synthase-RNAi construct was delivered into protocorm-like body (PLB) of Oncidium hybrid orchid. The transgenic orchids show down-regulated level of PSY and geranyl synthase gene. They displayed semi-dwarf phenotype and brilliant green leaves. The microscopic anatomy revealed development-arrested plastids with rare grana. The total carotenoid content was decreased and the efficiency of the photosynthetic electron transport was declined. The chlorophyll level and the expression of chlorophyll biosynthetic genes, such as OgGLUTR and OgCS were dramatically reduced. HPLC analysis showed that the endogenous level of gibberellic acid and abscisic acid in the dwarf transformants are 4-fold lower than in wild type plants. In addition, chilling tolerance of the transgenic Oncidium plants was reduced. The data showed that down-regulation of PSY resulted in alterations of gene expression in enzymes involved in many metabolic pathways, such as carotenoid, gibberellic acid, abscisic acid and chlorophyll biosynthetic pathway as well as causes predominant defects in plant growth and development.
authors.affiliation: Flower Research and Development Center, Zhejiang Academy of Agricultural Science, Hangzhou, 311202 Zhejiang China.
authors.forename: Jian-Xin
authors.initials: JX
authors.lastname: Liu
authors.affiliation: Institute of Plant Biology, College of Life Science, National Taiwan University, Roosevelt Road, Taipei, 10617 Taiwan ; Institute of Bioinformatics and Structural Biology & Department of Life Science, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu, 30013 Taiwan.
authors.forename: Chung-Yi
authors.initials: CY
authors.lastname: Chiou
authors.affiliation: Institute of Plant Biology, College of Life Science, National Taiwan University, Roosevelt Road, Taipei, 10617 Taiwan ; Ecological Materials Technology Department, Green Energy & Eco-technology System Center, ITRI South Campus, Industrial Technology Research Institute, Tainan, Taiwan.
authors.forename: Chin-Hui
authors.initials: CH
authors.lastname: Shen
authors.affiliation: Institute of Plant Biology, College of Life Science, National Taiwan University, Roosevelt Road, Taipei, 10617 Taiwan.
authors.forename: Peng-Jen
authors.initials: PJ
authors.lastname: Chen
authors.affiliation: Institute of Plant Biology, College of Life Science, National Taiwan University, Roosevelt Road, Taipei, 10617 Taiwan.
authors.forename: Yao-Chung
authors.initials: YC
authors.lastname: Liu
authors.affiliation: Institute of Forestry Research, Council of Agriculture, Taipei, Taiwan.
authors.forename: Chin-Der
authors.initials: CD
authors.lastname: Jian
authors.affiliation: Flower Research and Development Center, Zhejiang Academy of Agricultural Science, Hangzhou, 311202 Zhejiang China.
authors.forename: Xiao-Lan
authors.initials: XL
authors.lastname: Shen
authors.affiliation: Flower Research and Development Center, Zhejiang Academy of Agricultural Science, Hangzhou, 311202 Zhejiang China.
authors.forename: Fu-Quan
authors.initials: FQ
authors.lastname: Shen
authors.affiliation: Institute of Plant Biology, College of Life Science, National Taiwan University, Roosevelt Road, Taipei, 10617 Taiwan.
authors.forename: Kai-Wun
authors.initials: KW
authors.lastname: Yeh
keywords: Carotenoid; Oncidium orchid; Phytoene synthase; Plastid; RNA interference