title: Stability of transgenes in long-term micropropagation of plants of transgenic birch (Betula platyphylla).
abstract: The stability of integration and expression level of transgenes in long-term micropropagation clones of transgenic birch (Betula platyphylla Suk.) was examined. Multiplexed PCR and reverse primer PCR demonstrated stable integration of transgenes into regenerated plants. Expression levels of the bgt and gus genes among shoot plantlets, subcultured 4, 7, 9 and 15 times, were significantly different. The transcriptional expression level of extraneous genes in regenerated plants decreased with increasing subculture number. Transcriptional gene silencing (TGS) occured in regenerated transgenic lines. The silencing rate of GUS in the 5th subculture plants was 22-65%. TGS in regenerated plants could be reactivated with 5-azacytidine (Azac) at 50-200 microM. GUS and BGT protein expression was reactivated in the micropropagated transgenic birch plants when treated with Azac. A decrease in expression level with increasing number of subcultures is thus associated with DNA methylation.
authors.affiliation: College of Life Science, Northeast Forestry University, Harbin, 150040, China.
authors.forename: Fansuo
authors.initials: F
authors.lastname: Zeng
authors.forename: Jingjing
authors.initials: J
authors.lastname: Qian
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.forename: Yaguang
authors.initials: Y
authors.lastname: Zhan
authors.forename: Ying
authors.initials: Y
authors.lastname: Xin
authors.forename: Chuanping
authors.initials: C
authors.lastname: Yang
mesh_terms: D001374:Azacitidine / Q000494:pharmacology; D029662:Betula / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015152:Blotting, Northern; D019175:DNA Methylation; D004269:DNA, Bacterial / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D019076:Transgenes / Q000235:genetics / Q000502:physiology*
chemical_list: D004269:DNA, Bacterial; D010940:Plant Proteins; C036483:T-DNA; D001374:Azacitidine