[The patterns and influences of insertions, deletions and nucleotide substitutions in Solanaceae chloroplast genome]

Nucleotide substitution and indels (insertions and deletions) events are the major evolutionary driving forces. Comparisons of the indels and nucleotide substitution patterns were made in the chloroplast genomes between Solanum lycopersicum L. and Solanum bulbocastanum L., Nicotiana tomentosiformis L. and Nicotiana tabacum L. in Solanaceae. The influence of mutation on genome composition was analyzed. The indels and substitutions were not randomly distributed throughout the chloroplast genomes. The indels were in AT-rich regions. One base pair indels accounted for above 30% of the total indels. Most of the indels were short of 10 bp. The nucleotide substitutions showed Ts/Tv bias, but transversion frequency of T-->G and A-->C was increased significantly. Ts/Tv rates were lineage-specific. The Ts/Tv rate between S. lycopersicum and S. bulbocastanum was lower than that between N. tomentosiformis and N. tabacum. (A+T)/(G+C) rates varied in different lineages, which had an influence on (G+C)% of genomes. The changes in the (A+T)/(G+C) rates might correlate with the life histories of different species.