An example of microsatellite length variation in the mitochondrial genome of conifers

In the present study, the intergenic region between the mitochondrial genes encoding subunit 3 of NADH dehydrogenase (nad3) and ribosomal protein S12 (rps12) was shown to contain a G(n) mononucleotide microsatellite repeat. T his region was analysed in 15 species belonging to the genus Pinus and inte rspecific variation was detected in the form of repeat length polymorphism. Sequence analysis of a 576-bp region containing the microsatellite confirm ed that the variability was due to expansion and contraction of the repeat motif and that no point mutations were present in the coding regions of the two genes. This is the first report of the occurrence of a microsatellite polymorphism in plant mitochondria.