In an article entitled, “Mitochondrial Gene Diversity Associated with the atp9 Stop Codon in Natural Populations of Wild Carrot (Daucus carota ssp. carota) published in the current issue of J. Heredity, Jennifer R. Mandel et al. at the Department of Plant Biology, University of Georgia studied the mitochondrial gene atp9 in mitochondrial genome of wild carrot. The material consisted of 24 populations of D. carota collected from 24 populations in the eastern United States. In more than half of the surveyed 128 individuals, they found a CAA or AAA, rather than TAA to function as an atp9 stop codon. They found single nucleotide polymorphism associated with male-sterile and male-fertile phenotypic variants. The authors didn’t find any evidence for mitochondrial RNA editing of cytosine to uridine of the CAA stop codon in either floral or leaf tissue
They also found no evidence for mitochondrial RNA editing (cytosine to uridine) of the CAA stop codon in either floral or leaf tissue. The data presented by the authors suggest intragenic recombination, rather than the more common intergenic recombination. The data presented in the paper suggest that the mitochondrial genetic diversity was only modestly structured among populations with an FST of 0.34.*
*FST (F = Fixation) is a measure of the diversity of randomly chosen alleles within the same sub-population relative to that found in the entire population.