DNA replication directions

In addition, we observed that Type I mutants have all of their psbA gene copies mutated (99.9% probability) while no heteroplasmicity was found in Sp. plants (19). This indicates that a mechanism other than a high mutation rate must work to allow the release of individual plants that have their entire chloroplast population mutated. This could be due to the control of chloroplast DNA replication directed by mitochondrial or nuclear genomes. Indeed, a sequence homology has been found between mitochondrial DNA and part of the chloroplast psbA gene. Moreover, this homologous sequence is expressed as an RNA transcript in atrazine resistant C. album only and not in the susceptible plants (30). 

Hand, R., and Tamm, I., 1973, DNA replication Direction and rate of chain growth in mammalian cells, /. Cell Biol. 58 410. 

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See also in sourсe #XX -- [ ]

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