Evolution

Maintaining a massive mitochondrial genome

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Science  05 Jun 2015:
Vol. 348, Issue 6239, pp. 1103-1104
DOI: 10.1126/science.348.6239.1103-c

Silene noctiflora plants have an unusually large mitochondrial genome

PHOTO: © FLORALIMAGES/ALAMY

Even within the same species, flowering plants exhibit extreme differences in genome size, composition, and organization of their mitochondrial genomes. The coding sequence, however, is a different story. Wu et al. sequenced the mitochondrial genome of the plant Silene noctiflora and found that the genome consisted of 54 genes mapping to 59 circular chromosomes of varying size, many of which lacked genes. When compared with an individual from another population, both mitochondrial genomes contained the same number and organization of genes. However, variation was observed in total chromosome number (59 versus 63), suggesting that noncoding sequence had both been lost and gained between the populations but that selection maintains genetic information in the mitochondria.

Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1421397112 (2015).

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