Homoploid hybridization in the origin and evolution of wild diploid potato species

Abstract

The potatoes, Solanum L. section Petota Dumortier, are a group of species that possess a very broad range of biological diversity, and a wide geographical distribution in the Americas. These species constitute euploid series with somatic chromosome numbers ranging from 2n = 2x = 24 to 2n = 6x = 72. Although special attention has been given to the origin of polyploid potato species, principally the cultivated forms, that are major food crops, and hybridization has been accepted as an important evolutionary force in the section, the mechanisms involved in the origin and evolution of the diploid species have not been elucidated. Herein, we propose that homoploid hybridization is the main mechanism involved in the origin and evolution of the diploid potato species, and discuss the evidences that support our proposal.