Influence of culture medium and in vitro conditions on shoot regeneration in Solanum phureja monoploids and fertility of regenerated doubled monoploids

Incorporation of monoploids in practical breeding requires an efficient method of producing homozygous diploids. This study investigated factors for efficient regeneration of doubled monoploid (DM) potato, crossability of DMs and their field performance. Incorporation of silver thiosulphate (STS) in propagation medium for in vitro monoploid plantlets of Solanum phureja did not affect the frequency of cells with diploid(2 x ) nuclei but increased those with monoploid (1 x ) and decreased those with 4x nuclei. Higher shoot regeneration was obtained from leaf explants compared with stem explants. Induction of shoots from calluswas affected neither by light during incubation nor by overnight treatment with a benzyl adenine pulse. Female fertility based on seed set after pollination of DMs with heterozygous diploid clones varied among DMs but encouraged their utilization in practical breeding.