| Research Abstract |
To study the molecular basis of cytoplasmic male sterility (CMS) in sugarbeet, we have conducted a detailed comparison of the mitochondrial genomes of two sugarbeet lines, one containing a fertile (N) cytoplasm and the other a male sterile one. The two genomes have approximately 330kb of common sequences but there is considerable variation in sequence organization which can be accounted for by genome rearrangements.
Transcripts for known mitochondrial genes and regions of the two sugarbeet genomes known to be rearranged relative to one another were compared among male-fertile, CMS and nuclear-restored sugarbeet genotypes. In most instances, identical transcript patterns were observed for all three, mtRNAs (prepared from leaves or flower buds), indicating that rearrangement events did not occur within transcriptional units. Altered transcript patterns were, however, identified for six genes, coxI,coxII,atpA,rps3, orf324, and orf1.
Interestingly, the coxI transcripts were found to be significantly affected by nuclear background, whereas unclear background has no effect on the transcripts of other five genes.
The results suggest that nuclear-restorer gene (s) have an effect on coxI transcript patterns and implicate coxI in sugarbeet male sterility.
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