title: Quantitative determination of mosaic GFP gene expression in tobacco.
abstract: A specific form of gene silencing that was observed visually as a mosaic distribution of fluorescent and non-fluorescent cells apparently dispersed at random within tissues was found in a few green fluorescent protein (GFP)-transformed tobacco lines. To characterize this event quantitatively, we studied flow cytometric measurements in GFP-expressing and -silenced cells in T1 and T2 progeny of four selected plants. The proportion of silenced cells varied considerably among the T1 lines but with notable genotype differences. Mosaic expression was inherited into the T2 generation in which the majority of progenies tested exhibited a level of silencing similar to that of their T1 parental plants. However, in some T2 progenies segregation, evident as a decrease or increase in the proportion of fluorescent cells, was observed. We discuss several factors, such as copy number, promoter activity or polyploidy, that may be the possible causes of the gene silencing, but none sufficiently explain the appearance of the mosaic distribution.
authors.affiliation: Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000, Slovenia.
authors.forename: M T
authors.initials: MT
authors.lastname: Bastar
authors.forename: Z
authors.initials: Z
authors.lastname: Luthar
authors.forename: S
authors.initials: S
authors.lastname: Skof
authors.forename: B
authors.initials: B
authors.lastname: Bohanec
mesh_terms: D001483:Base Sequence; D017931:DNA Primers; D005434:Flow Cytometry; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics* / Q000378:metabolism; D009030:Mosaicism / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000166:cytology / Q000235:genetics; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000378:metabolism; D014026:Nicotiana / Q000166:cytology / Q000235:genetics* / Q000378:metabolism
chemical_list: D017931:DNA Primers; D008164:Luminescent Proteins; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins