title: Switchgrass (Panicum virgatum L.) polyubiquitin gene (PvUbi1 and PvUbi2) promoters for use in plant transformation.
abstract: BACKGROUND
  The ubiquitin protein is present in all eukaryotic cells and promoters from ubiquitin genes are good candidates to regulate the constitutive expression of transgenes in plants. Therefore, two switchgrass (Panicum virgatum L.) ubiquitin genes (PvUbi1 and PvUbi2) were cloned and characterized. Reporter constructs were produced containing the isolated 5' upstream regulatory regions of the coding sequences (i.e. PvUbi1 and PvUbi2 promoters) fused to the uidA coding region (GUS) and tested for transient and stable expression in a variety of plant species and tissues.
  
  
  RESULTS
  PvUbi1 consists of 607 bp containing cis-acting regulatory elements, a 5' untranslated region (UTR) containing a 93 bp non-coding exon and a 1291 bp intron, and a 918 bp open reading frame (ORF) that encodes four tandem, head -to-tail ubiquitin monomer repeats followed by a 191 bp 3' UTR. PvUbi2 consists of 692 bp containing cis-acting regulatory elements, a 5' UTR containing a 97 bp non-coding exon and a 1072 bp intron, a 1146 bp ORF that encodes five tandem ubiquitin monomer repeats and a 183 bp 3' UTR. PvUbi1 and PvUbi2 were expressed in all examined switchgrass tissues as measured by qRT-PCR. Using biolistic bombardment, PvUbi1 and PvUbi2 promoters showed strong expression in switchgrass and rice callus, equaling or surpassing the expression levels of the CaMV 35S, 2x35S, ZmUbi1, and OsAct1 promoters. GUS staining following stable transformation in rice demonstrated that the PvUbi1 and PvUbi2 promoters drove expression in all examined tissues. When stably transformed into tobacco (Nicotiana tabacum), the PvUbi2+3 and PvUbi2+9 promoter fusion variants showed expression in vascular and reproductive tissues.
  
  
  CONCLUSIONS
  The PvUbi1 and PvUbi2 promoters drive expression in switchgrass, rice and tobacco and are strong constitutive promoter candidates that will be useful in genetic transformation of monocots and dicots.
authors: Department of Plant Sciences, University of Tennessee, Knoxville, TN 37996, USA. dmann1@utk.edu
authors: David G J
authors: DG
authors: Mann
authors: Zachary R
authors: ZR
authors: King
authors: Wusheng
authors: W
authors: Liu
authors: Blake L
authors: BL
authors: Joyce
authors: Ryan J
authors: RJ
authors: Percifield
authors: Jennifer S
authors: JS
authors: Hawkins
authors: Peter R
authors: PR
authors: LaFayette
authors: Barbara J
authors: BJ
authors: Artelt
authors: Jason N
authors: JN
authors: Burris
authors: Mitra
authors: M
authors: Mazarei
authors: Jeffrey L
authors: JL
authors: Bennetzen
authors: Wayne A
authors: WA
authors: Parrott
authors: Charles N
authors: CN
authors: Stewart
mesh_terms: D017343:Genes, Plant; D005821:Genetic Techniques; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics; D008897:Panicum / Q000235:genetics*; D030821:Plants, Genetically Modified; D025821:Polyubiquitin / Q000235:genetics*; D011401:Promoter Regions, Genetic; D014026:Nicotiana / Q000235:genetics; D014170:Transformation, Genetic; D019076:Transgenes
chemical_list: D025821:Polyubiquitin