title: Developmental changes in abundance of the VSPbeta protein following nuclear transformation of maize with the soybean vspbeta cDNA.
abstract: BACKGROUND
  Developing monocots that accumulate more vegetative tissue protein is one strategy for improving nitrogen-sequestration and nutritive value of forage and silage crops. In soybeans (a dicotyledonous legume), the vspA and B genes encode subunits of a dimeric vegetative storage protein that plays an important role in nitrogen storage in vegetative tissues. Similar genes are found in monocots; however, they do not accumulate in leaves as storage proteins, and the ability of monocot leaves to support accumulation of an ectopically expressed soybean VSP is in question. To test this, transgenic maize (Zea Mays L. Hi-II hybrid) lines were created expressing soybean vspB from a maize ubiquitin Ubi-1 promoter.
  
  
  RESULTS
  From 81 bombardments, 101 plants were regenerated, and plants from five independent lines produced vspB transcripts and VSPbeta polypeptides. In leaves from seven-week-old plants (prior to flowering), VSPbeta accumulated to 0.5% of the soluble leaf protein in primary transgenic plants (R0), but to only 0.03% in R1 plants. During seed-filling (silage-stage) in R1 plants, the VSPbeta protein was no longer detected in leaves and stems despite continued presence of the vspB RNA. The RNA transcripts for this peptide either became less efficiently translated, or the VSPbeta protein became unstable during seed-fill.
  
  
  CONCLUSIONS
  Developmental differences in the accumulation of soybean VSPbeta when transgenically expressed in maize show that despite no changes in the vspB transcript level, VSPbeta protein that is readily detected in leaves of preflowering plants, becomes undetectable as seeds begin to develop.
authors.affiliation: Instituto de Ciências Biológicas/Faculdade de Agronomia e Medicina Veterinária, Universidade de Passo Fundo, Passo Fundo - RS, 99001-970, Brazil. magali@upf.br <magali@upf.br>
authors.forename: Magali F
authors.initials: MF
authors.lastname: Grando
authors.forename: Rex L
authors.initials: RL
authors.lastname: Smith
authors.forename: Cristina
authors.initials: C
authors.lastname: Moreira
authors.forename: Brian T
authors.initials: BT
authors.lastname: Scully
authors.forename: Robert G
authors.initials: RG
authors.lastname: Shatters
mesh_terms: D015152:Blotting, Northern; D015139:Blotting, Southern; D015153:Blotting, Western; D002467:Cell Nucleus / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics / Q000378:metabolism; D015246:Deoxyribonuclease EcoRI / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018547:Plant Stems / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D025822:Ubiquitin C / Q000235:genetics; D003313:Zea mays / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D018744:DNA, Plant; D010940:Plant Proteins; D018749:RNA, Plant; D011993:Recombinant Fusion Proteins; C417884:Ubi-1 protein, Zea mays; D025822:Ubiquitin C; C078149:vspB protein, Glycine max; D015246:Deoxyribonuclease EcoRI
references.citation: Plant Mol Biol. 1987 Jul;9(4):315-24
references.pmid: 24277084
references.citation: Genetica. 1993;90(2-3):181-200
references.pmid: 8119592
references.citation: Plant Physiol. 1988 May;87(1):250-4
references.pmid: 16666113
references.citation: Transgenic Res. 1996 May;5(3):179-85
references.pmid: 8673145
references.citation: Transgenic Res. 1996 May;5(3):213-8
references.pmid: 8673150
references.citation: Plant Physiol. 1995 Jan;107(1):13-23
references.pmid: 12228338
references.citation: Plant Physiol. 1989 Jan;89(1):309-15
references.pmid: 16666532
references.citation: Plant J. 1992 Mar;2(2):181-92
references.pmid: 1302048
references.citation: Plant Cell Rep. 1993 Jan;12(2):84-8
references.pmid: 24202074
references.citation: Anal Biochem. 1980 Jul 1;105(2):361-3
references.pmid: 6161559
references.citation: J Mol Biol. 1975 Nov 5;98(3):503-17
references.pmid: 1195397
references.citation: Transgenic Res. 2003 Feb;12(1):123-6
references.pmid: 12650531
references.citation: Plant Mol Biol. 1992 Sep;19(6):951-8
references.pmid: 1511140
references.citation: J Exp Bot. 2002 Sep;53(376):1867-70
references.pmid: 12177124
references.citation: Anal Biochem. 1976 May 7;72:248-54
references.pmid: 942051
references.citation: Anal Biochem. 1987 Apr;162(1):156-9
references.pmid: 2440339
references.citation: Proc Natl Acad Sci U S A. 1998 Oct 27;95(22):12995-9
references.pmid: 9789029
references.citation: Plant Mol Biol. 1988 Nov;11(6):845-56
references.pmid: 24272634
references.citation: Plant Physiol. 1983 Sep;73(1):125-9
references.pmid: 16663160