Sequence of a mitochondrial plasmid of sunflower (Helianthus annuus) and its relationship to other mitochondrial plasmids

A circular plasmid called plT is found in mitochondria of sunflower (Helianthus annuus). Its nucleotide sequence has been determined and analyzed in order to understand its possible role and origin. The nucleotide sequence exhibits a 159 base pair region with highly organized repeats. The sequence of plT shows no major homology with other plasmids of higher plants although organized patterns are present in the circular plasmids. We also report the existence of two related mitochondrial plasmids in a line of H. annuus and in the H. petiolaris fallax species. In addition, plT plasmid has been detected in total cellular DNA of male-sterile sunflower with a copy number of a hundred times lower than in the male-fertile one.