Abstract: PPrevious research on the NCa, a cytoplasmic male sterile (CMS) line in Brassica napus, showed that it might hold a new type of sterile cytoplasm. RFLP analysis of the mitochondrial (mt) DNA of the 5 CMS lines, i.e., NCa, pol, nap, ogura and tour CMS, combining 14 probes originated from mt genes with 4 endonuclease, such as EcoR I, BamH I, Hind III and Pst I, was performed and detected that 42 combinations of probe/enzyme out of the total 54 combinations could discover the different bands among the 5 CMS lines and then distinguish some of them from the others. Moreover, 5 combinations of atp1/EcoR I, atp1/Hind III, atp6/EcoR I, atp8/BamH I, and orf139/BamH I, could powerfully distinguish the 5 CMS lines from each other. These 5 combinations of probe/enzyme could be exploited as markers to identify the cytoplasmic type of rapeseed CMS. These results definitely demonstrated the NCa CMS hold a new type of sterile cytoplasm different from pol, nap, ogura and tour CMS. Twenty-two primers were designed according to the Arabidopsis mt genome and the mt regions which controlled the cytoplasmic male sterility of pol, nap, ogura CMS lines, and were used in PCR analysis of mt DNA from the above five CMS lines. The PCR results proved that no one of the 22 primers could distinguish the NCa CMS from the other four.

Key words: Brassica napus, Cytoplasmic male sterility, sterile cytoplasm classification, PCR, RFLP