Authors: JianZhi Huang TingChi Cheng PeiJung Wen MingHsiun Hsieh FureChyi Chen
Publish Date: 2009/07/28
Volume: 28, Issue: 10, Pages: 1475-1486
Abstract
Two pathways are used by higher plants for the biosynthesis of isoprenoid precursors the mevalonate pathway in the cytosol and a 2Cmethylderythritol 4phosphate MEP pathway in the plastids with 1hydroxy2methyl2Ebutenyl 4diphosphate reductase HDR catalyzing the last step in the MEP pathway In order to understand the contribution of MEP pathway in isoprenoid biosynthesis of Oncidium orchid a fulllength cDNA corresponding to HDR from the flower tissues of Oncidium Gower Ramsey was cloned The deduced OncHDR amino acid sequence contains a plastid signal peptide at the Nterminus and four conserved cysteine residues RTPCR analysis of HDR in Oncidium flowering plants revealed ubiquitous expression in organs and tissues with preferential expression in the floral organs Phylogenetic analysis revealed evolutionary conservation of the encoding HDR protein sequence The genomic sequence of the HDR in Oncidium is similar to that in Arabidopsis grape and rice in structure Successful complementation by OncHDR of an E coli hdr − mutant confirmed its function Transgenic tobacco carrying the OncHDR promoterGUS gene fusion showed expression in most tissues as well as in reproductive organs as revealed by histochemical staining Light induced strong GUS expression driven by the OncHDR promoter in transgenic tobacco seedlings Taken together our data suggest a role for OncHDR as a lightactivated gene
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