title: Gene silencing studies in the gymnosperm species Pinus radiata.
abstract: A biolistic transformation procedure was used to transform embryogenic Pinus radiata tissue with constructs containing the Zea mays UBI1 (ubiquitin)-promoter followed by the P. radiata CAD (cinnamyl alcohol dehydrogenase) cDNA in sense or anti-sense orientation or in the form of an inverted-repeat. The effect of the different constructs on silencing the endogenous CAD gene was monitored in embryogenic tissue and somatic seedlings of 28 P. radiata transclones. Quantitative CAD measurements demonstrated that the construct containing an inverted-repeat of the CAD cDNA was most efficient in triggering gene silencing in P. radiata. Northern hybridization experiments with silenced transclones revealed that reduced CAD activities were the result of reduced steady state levels of the targeted CAD mRNA. Monitoring of the activity of the UBI1-promoter in the P. radiata transclones and heat-shock experiments with transgenic somatic P. radiata seedlings indicated that gene silencing is positively correlated with the expression level of the transgene. The obtained data are also consistent with a role for the expression level of the endogenous CAD gene in gene silencing.
authors.affiliation: Cellwall Biotechnology Centre (CBC), Forest Research, Private Bag 3020, Rotorua, New Zealand. armin.wagner@forestresearch.co.nz
authors.forename: Armin
authors.initials: A
authors.lastname: Wagner
authors.forename: Lorelle
authors.initials: L
authors.lastname: Phillips
authors.forename: Reena D
authors.initials: RD
authors.lastname: Narayan
authors.forename: Judy M
authors.initials: JM
authors.lastname: Moody
authors.forename: Barbara
authors.initials: B
authors.lastname: Geddes
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D020868:Gene Silencing / Q000502:physiology*; D028223:Pinus / Q000196:embryology / Q000235:genetics* / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics; D018520:Plant Shoots / Q000196:embryology / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000196:embryology / Q000235:genetics* / Q000254:growth & development; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D012639:Seeds / Q000196:embryology / Q000235:genetics / Q000254:growth & development; D014170:Transformation, Genetic / Q000235:genetics*; D019076:Transgenes / Q000235:genetics; D025822:Ubiquitin C / Q000235:genetics
chemical_list: D018076:DNA, Complementary; D018744:DNA, Plant; D010940:Plant Proteins; D012333:RNA, Messenger; C417884:Ubi-1 protein, Zea mays; D025822:Ubiquitin C; D000429:Alcohol Oxidoreductases; C018656:cinnamyl alcohol dehydrogenase