Abstract:

Previous studies verified NCa CMS was a novel CMS and would be rather important for improving cytoplasm monotony in rapeseed hybrid utilization, but the transcriptional pattern of NCa CMS was not investigated yet. So in this paper, northern blot analysis was conducted with mitochondrial RNA from floral buds of NCa CMS, maintainer line and fertile F₁ using 10 mitochondrial genes as probes. Transcripts of seven probes of atp6, atp1, cox1, cox2, cob, rrn5S, rrn26S, showed no diversity among floral buds of these three materials, which indicated that the expression of these probes has no relationship with NCa sterility. However, differences in transcriptional patterns were observed when using orf222, orf139 and atp9 as probes. Three transcripts of orf222 were detected in the floral buds of NCa CMS and fertile F₁ while no transcript was detected in floral buds of the maintainer line. The transcription of orf139 was similar to that of orf222 but only two transcripts of 0.8 and 0.6 kb. The atp9 probe detected a single transcript of 0.6 kb in NCa CMS and maintainer line but an additional transcript of 1.2 kb in fertile F₁. The results suggested that the expression of orf222, orf139 and atp9 might be associated with NCa sterility. And how the restorer gene regulates the expression of these candidate sterility-related mitochondrial genes and then causes fertility restoration in fertile F₁ is not clear and detailed research about the regulation mechanism is underway.

Key words: Brassica napus L., Cytoplasmic male sterility (CMS), Mitochondrial gene expression, Fertility restorer gene, Transcriptional regulation