title: Somatic variation during long-term subculturing of plant cells caused by insertion of a transposable element in a phenylalanine ammonia-lyase (PAL) gene.
abstract: We have identified a new En/Spm-like transposable element, Tdc1, in the 5' flanking region of a phenylalanine ammonia-lyase gene (gDcPAL1) that is normally induced by transferring cells of carrot suspension cultures to fresh liquid medium (transfer or dilution effect). The initial integration into gDcPAL1 occurred more than 4 years after culture initiation. Tdc1 was first detected in gDcPAL1 genomic clones of a genomic library made from cells of the same cultured cell line 7 years after its initiation and thus following repeated subculturing. Twelve years after initiation, about 5-10% of the cells had Tdc1 inserted into the gDcPAL1 gene, indicating that Tdc1 insertion into gDcPAL1 occurred in one (or more) cell(s) during the first 4-7 years of subculturing. These mutant cells did not disappear during numerous passages; instead the proportion of cells having this Tdc1 inserted into gDcPAL1 has been increasing over the last 5 years. The promoter activity and the inducibility by transfer/dilution of the gDcPAL1 gene harboring Tdc1 is reduced relative to wild type. Finally, we show that insertion of a transposable element is one of the mechanisms that can cause variation of plant cell cultures during repeated subculture.
authors.affiliation: Department of Biotechnology, Faculty of Technology, Tokyo University of Agriculture and Technology, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ozeki
authors.forename: E
authors.initials: E
authors.lastname: Davies
authors.forename: J
authors.initials: J
authors.lastname: Takeda
mesh_terms: D000595:Amino Acid Sequence; D015139:Blotting, Southern; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004251:DNA Transposable Elements / Q000235:genetics*; D018552:Daucus carota / Q000166:cytology / Q000201:enzymology / Q000235:genetics*; D015245:Deoxyribonuclease BamHI / Q000378:metabolism; D015246:Deoxyribonuclease EcoRI / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D015870:Gene Expression; D017343:Genes, Plant / Q000235:genetics; D017930:Genes, Reporter; D014644:Genetic Variation; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010641:Phenotype; D010650:Phenylalanine Ammonia-Lyase / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D017386:Sequence Homology, Amino Acid
chemical_list: D004251:DNA Transposable Elements; D015245:Deoxyribonuclease BamHI; D015246:Deoxyribonuclease EcoRI; C034510:CTCGAG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific; D010650:Phenylalanine Ammonia-Lyase