title: Cytoplasmic inhibition of carotenoid biosynthesis with virus-derived RNA.
abstract: The carotenoid biosynthetic pathway in higher plants was manipulated by using an RNA viral vector. A cDNA encoding phytoene synthase and a partial cDNA encoding phytoene desaturase (PDS) were placed under the transcriptional control of a tobamovirus subgenomic promoter. One to two weeks after inoculation, systemically infected Nicotiana benthamiana plants were analyzed for phytoene. Leaves from transfected plants expressing phytoene synthase developed a bright orange phenotype and accumulated high levels of phytoene. Cytoplasmic inhibition of plant gene expression by viral RNA was demonstrated with an antisense RNA transcript to a partial PDS cDNA derived from tomato. The leaves of the plants transfected with the antisense PDS sequence developed a white phenotype and also accumulated high levels of phytoene. A partial cDNA to the corresponding N. benthamiana PDS gene was isolated and found to share significant homology with the tomato antisense PDS transcript. This work demonstrates that an episomal RNA viral vector can be used to deliberately manipulate a major, eukaryotic biosynthetic pathway. In addition, our results indicate that an antisense transcript generated in the cytoplasm of a plant cell can turn off endogenous gene expression.
authors.affiliation: Biosource Technologies, Vacaville, CA 95688.
authors.forename: M H
authors.initials: MH
authors.lastname: Kumagai
authors.forename: J
authors.initials: J
authors.lastname: Donson
authors.forename: G
authors.initials: G
authors.lastname: della-Cioppa
authors.forename: D
authors.initials: D
authors.lastname: Harvey
authors.forename: K
authors.initials: K
authors.lastname: Hanley
authors.forename: L K
authors.initials: LK
authors.lastname: Grill
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002338:Carotenoids / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016376:Oligonucleotides, Antisense / Q000737:chemistry; D010088:Oxidoreductases / Q000235:genetics*; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics; D012367:RNA, Viral / Q000235:genetics; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013329:Structure-Activity Relationship; D017898:Tobamovirus / Q000235:genetics
chemical_list: D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D012367:RNA, Viral; D002338:Carotenoids; D010088:Oxidoreductases; C022398:phytoene dehydrogenase