Romano Eduardo, Soares Alexandre, Proite Karina, Neiva Suzana, Grossi Maíra, Faria Josias C, Rech Elíbio L, Aragão Francisco J L
Embrapa Recursos Genéticos e Biotecnologia, Parque Estação Biológica, Final Av. W3 Norte, 70770-900 Brasília, DF, Brazil.
Genet Mol Res. 2005 Jun 30;4(2):177-84.
Transgene elimination is a poorly studied phenomenon in plants. We made genetic and molecular studies of a transgenic dry bean line immune to bean golden mosaic geminivirus and a soybean line. In both lines, the transgenes were stable during the vegetative phase but were eliminated during meiosis. Due to its potential biotechnological value, this transgenic line was micropropagated by grafting and the vegetative copies were studied for more than two years. More than 300 plants of progeny were obtained during this period, demonstrating that the phenomenon of elimination was consistently repeated and offering an opportunity for detailed study of transgene elimination, including the characterization of the integration sites. Cloning and sequencing of the transgenic loci, reciprocal crosses to untransformed plants, genomic DNA blots, and GUS assays were performed in the transgenic lines. Based on the molecular and genetic characterization, possible mechanisms involved in transgene elimination include intrachromosomal recombination, genetic instability resulting from the tissue culture manipulations, and co-elimination of transgenes, triggered by a process of genome defense.
转基因消除在植物中是一个研究较少的现象。我们对一个对菜豆金色花叶双生病毒免疫的转基因菜豆品系和一个大豆品系进行了遗传和分子研究。在这两个品系中，转基因在营养生长阶段是稳定的，但在减数分裂期间被消除。由于其潜在的生物技术价值，这个转基因品系通过嫁接进行微繁殖，并对营养体拷贝进行了两年多的研究。在此期间获得了300多株后代植株，表明消除现象持续重复出现，为详细研究转基因消除提供了机会，包括整合位点的表征。在转基因品系中进行了转基因位点的克隆和测序、与未转化植株的正反交、基因组DNA印迹分析和GUS检测。基于分子和遗传特征，转基因消除可能涉及的机制包括染色体内重组、组织培养操作导致的遗传不稳定性以及由基因组防御过程引发的转基因共消除。
