Fig 7. Schematic representation of evolution of cpDNA types in potato.

The W-type is the primitive type of potato plastome from which other types were derived. A 241 bp deletion in the W-type gave rise to the T-type cpDNA [11]. The W2 (W”) is derived from W due to a single nucleotide change. Similarly, the C-type is derived from the W-type by a single nucleotide change which further formed the S- and A-type plastomes. The A-type derived from the C-type due to the formation of a second restriction site by an SNP, while a 48 bp deletion in the C-type led to the S-type.