Department of Agriculture, University of Helsinki, PO Box 27, FI-00014, Helsinki, Finland.
Chromosome Res. 2012 Apr;20(3):353-61. doi: 10.1007/s10577-012-9280-5. Epub 2012 Apr 3.
In spring turnip rape (Brassica rapa L. spp. oleifera), the most promising F1 hybrid system would be the Ogu-INRA CMS/Rf system. A Kosena fertility restorer gene Rfk1, homolog of the Ogura restorer gene Rfo, was successfully transferred from oilseed rape into turnip rape and that restored the fertility in female lines carrying Ogura cms. The trait was, however, unstable in subsequent generations. The physical localization of the radish chromosomal region carrying the Rfk1 gene was investigated using genomic in situ hybridization (GISH) and bacterial artificial chromosome-fluorescence in situ hybridization (BAC-FISH) methods. The metaphase chromosomes were hybridized using radish DNA as the genomic probe and BAC64 probe, which is linked with Rfo gene. Both probes showed a signal in the chromosome spreads of the restorer line 4021-2 Rfk of turnip rape but not in the negative control line 4021B. The GISH analyses clearly showed that the turnip rape restorer plants were either monosomic (2n=2x=20+1R) or disomic (2n=2x=20+2R) addition lines with one or two copies of a single alien chromosome region originating from radish. In the BAC-FISH analysis, double dot signals were detected in subterminal parts of the radish chromosome arms showing that the fertility restorer gene Rfk1 was located in this additional radish chromosome. Detected disomic addition lines were found to be unstable for turnip rape hybrid production. Using the BAC-FISH analysis, weak signals were sometimes visible in two chromosomes of turnip rape and a homologous region of Rfk1 in chromosome 9 of the B. rapa A genome was verified with BLAST analysis. In the future, this homologous area in A genome could be substituted with radish chromosome area carrying the Rfk1 gene.
在春油菜（芸薹属甘蓝型亚种）中，最有前途的 F1 杂种系统将是 Ogu-INRA CMS/Rf 系统。Kosena 育性恢复基因 Rfk1，Ogura 恢复基因 Rfo 的同源物，已成功从油菜转移到油菜中，并恢复了携带 Ogura CMS 的雌性系的育性。然而，该性状在随后的几代中不稳定。使用基因组原位杂交（GISH）和细菌人工染色体-荧光原位杂交（BAC-FISH）方法研究了携带 Rfk1 基因的萝卜染色体区域的物理定位。使用萝卜 DNA 作为基因组探针和与 Rfo 基因相连的 BAC64 探针对中期染色体进行杂交。两个探针都在油菜恢复系 4021-2 Rfk 的染色体分散体中显示信号，但在阴性对照系 4021B 中没有显示信号。GISH 分析清楚地表明，油菜恢复系植物要么是单倍体（2n=2x=20+1R），要么是二倍体（2n=2x=20+2R）添加系，带有一个或两个来自萝卜的单个外源染色体区域的拷贝。在 BAC-FISH 分析中，在萝卜染色体臂的末端部分检测到双点信号，表明育性恢复基因 Rfk1 位于该附加萝卜染色体上。检测到的二倍体添加系在油菜杂种生产中不稳定。使用 BAC-FISH 分析，有时在油菜的两条染色体和 B. rapa A 基因组第 9 号染色体的 Rfk1 同源区域中可以看到弱信号，并通过 BLAST 分析验证了 B. rapa A 基因组中的同源区域。在未来，A 基因组中的这个同源区域可以用携带 Rfk1 基因的萝卜染色体区域取代。
