Biological Research Centre, Hungarian Academy of Sciences, P.O. Box 521, H-6701, Szeged, Hungary.
Theor Appl Genet. 1992 Sep;84(7-8):866-73. doi: 10.1007/BF00227398.
Vegetative segregation of a mixed plastid population in protoplast fusion-derived cell lines can be directed by a selection favouring the multiplication of one of the parental plastid types. This report defines some of the critical conditions leading to a homogeneous plastid population in cybrid plants generated by protoplast fusion between Nicotiana plumbaginifolia and an albino and streptomycin-resistant N. tabacum plastid mutant. Light (1,500 lx) conferred a strong selective advantage to chloroplasts versus albino plastids, while the lack of this effect in dim light (300 lx) indicated that a sufficient light intensity is essential to the phenomenon. Selection on streptomycin-containing medium in the dark, however, led to the preferential multiplication of resistant plastids. Streptomycin selection of resistant chloroplasts in the light, consequently, results in a plastid selection of doubled stringency. In another experiment a definite, but leaky, selection for chloroplast recombination (selection for greening on streptomycin-containing medium in dim light) was used to reveal various recombination products. Protoplast fusion in fact resulted in cybrid plants showing only simple chimeric segregation of unchanged parental plastids. These results demonstrate the essential requirement for stringent plastid selection, as defined by cell culture conditions, to precede the formation of shoots expected to possess the desired plastid genetic composition.
质体杂种中混合质体群体的营养分离可通过有利于双亲质体类型之一增殖的选择来定向。本文报道了在通过原生质体融合产生的烟草原生质体和白化及链霉素抗性烟草质体突变体杂种中，获得均一质体群体所必需的一些关键条件。强光（1500 lx）赋予叶绿体相对于白化质体的强烈选择优势，而在弱光（300 lx）下无此效应，表明此现象需要足够的光强。然而，在黑暗中用含链霉素的培养基选择，则导致抗性质体的优先增殖。因此，在光下用链霉素选择抗性叶绿体，导致质体选择的严格性加倍。在另一个实验中，用明确但有渗漏的叶绿体重组选择（在弱光下用含链霉素的培养基选择绿苗）来揭示各种重组产物。原生质体融合实际上导致杂种植物仅表现未改变的亲本质体的简单嵌合分离。这些结果表明，在形成预期具有所需质体遗传组成的芽之前，需要严格的质体选择，正如细胞培养条件所定义的那样。
