In Vitro Production of Potatoes Bearing Resistance to Fungal Diseases

Abstract

In strict taxonomic terms, Solarium tuberosum L. does not describe a species but summarizes rather a collection of cultivars derived from the South American species S. andigenum and S. tuberosum, which are still grown in Peru. Historically, the initial “seed stock” for the eastern hemisphere (S. tuberosum ssp. tuberosum and S. tuberosum ssp. andigenum) was carried over to Spain and England in the late 16th Century. It does not seem likely that these seed potatoes had been carefully selected from an array of wild species such as S. commersonii, S. maglia, S. vavilovi and others. While these truly wild species possess 24 chromosomes, S. andigenum and S. tuberosum both contain 48 chromosomes, most likely introduced by an early spontaneous mutation. It is probable that the potatoes domesticated in South America were selected primarily for lack of a bitter and toxic principle in the tubers, which has since been identified as a glycoalkaloid fraction. South American natives withstood the high glycoalkaloid contents of wild potato species by the simultaneous consumption of edible clays (Johns 1985). Clearly, potatoes were also screened for their hardiness to the climate as well as for their tuber size.