Baldev A, Gaikwad K, Kirti P B, Mohapatra T, Prakash S, Chopra V L
National Research Centre for Plant Biotechnology, Indian Agricultural Research Institute, New Delhi.
Mol Gen Genet. 1998 Nov;260(4):357-61. doi: 10.1007/s004380050904.
We document here the presence of a recombinant plastome in a cytoplasmic male sterile (CMS) line of Brassica juncea developed from the somatic hybrid Trachystoma ballii + B. juncea. Restriction endonuclease digestion of the chloroplast (cp) DNA has revealed that the recombinant plastome gives rise to novel fragments in addition to the parent-specific fragments. Analysis of the 16S rRNA region by Southern hybridization shows no variation between B. juncea, T. ballii and the CMS line. The rbcL gene region of the recombinant plastome is identical to that in T. ballii. Analysis with probes for psbA and psbD using single and double DNA digests indicates that the hybridization patterns of the recombinant plastome are identical to those of the parents in digests obtained with some restriction enzymes, while novel bands hybridize to probes in other digests. In the psbA region, a B. juncea-specific PstI site and a T. ballii-specific EcoRI site are found in the recombinant plastome. The pshD region of the recombinant plastome contains a B. juncea-specific HindIII site and T. ballii-specific BamHI and HpaII sites. These results indicate the occurrence of intergenomic recombination between the chloroplasts of T. ballii and B. juncea in the somatic hybrid from which the CMS line was developed. The recombined plastome appears to be a mosaic of fragments specific to both parents and the recombination event has occurred in the single-copy regions. These recombinational events have not caused any imbalance in the recombinant plastome in terms of chloroplast-related functions, which have remained stable over generations.
我们在此记录了在由体细胞杂种Trachystoma ballii + 芥菜型油菜培育出的芥菜型油菜细胞质雄性不育（CMS）系中存在重组质体基因组。对叶绿体（cp）DNA进行限制性内切酶消化后发现，重组质体基因组除了产生亲本特异性片段外，还产生了新的片段。通过Southern杂交分析16S rRNA区域，结果表明芥菜型油菜、Trachystoma ballii和CMS系之间没有差异。重组质体基因组的rbcL基因区域与Trachystoma ballii中的相同。使用单酶切和双酶切，用psbA和psbD探针进行分析表明，在一些限制性酶切获得的消化产物中，重组质体基因组的杂交模式与亲本相同，而在其他消化产物中有新的条带与探针杂交。在psbA区域，重组质体基因组中发现了一个芥菜型油菜特异性的PstI位点和一个Trachystoma ballii特异性的EcoRI位点。重组质体基因组的pshD区域包含一个芥菜型油菜特异性的HindIII位点以及Trachystoma ballii特异性的BamHI和HpaII位点。这些结果表明，在培育CMS系的体细胞杂种中，Trachystoma ballii和芥菜型油菜的叶绿体之间发生了基因组间重组。重组后的质体基因组似乎是双亲特异性片段的镶嵌体，重组事件发生在单拷贝区域。这些重组事件在叶绿体相关功能方面未导致重组质体基因组出现任何失衡，这些功能在多代中一直保持稳定。
