Overcoming cross-incompatibility among some Mexican diploid species of Solanum

Abstract

Species of Solanum belonging to the section Tuberarium and occurring in Mexico have long been of interest to potato breeders, as several of them possess resistance to the late-blight caused by Phytophthora infestans de Bary. Like the tuberbearing species of Solanum found in South America, the Mexican species also form a polyploid series comprising diploids (2n=24), triploids (2n=36), tetra-ploids (2n=48), pentaploids (2n=60) and hexa-ploids (2n=72). These species have been classified in eight distinct taxonomic series, and our information concerning the cytogenetic affinities among them is still very fragmentary. As a preliminary towards gathering such data, a systematic survey of ability to cross among the diploid species occurring in Mexico was undertaken by me, during the summer of 1953, at the Inter-regional Potato Introduction Station, Sturgeon Bay, Wisconsin.