Morphology and [14C]Gibberellin A12 Metabolism in WildType and Dwarf Solanum tuberosum ssp. Andigena Grown under Long and Short Photoperiods

Abstract

Potato tuberization is promoted by short days and inhibited by applications of gibberellin (GA). Wildtype Solanum tuberosum ssp. andigena required short days for tuberization, whereas their dwarf siblings tuberized under long days. Nevertheless, shortening the photoperiod also enhanced tuberization of dwarf plants and caused an increase in leaf angle and a reduction in internode length of both genotypes. The potential role of GA metabolism in tuberization as influenced by dwarfing and photoperiod was investigated by studying the metabolism of [14C]GA12 in shoots of wild-type and dwarf potato plants. Measurement of metabolite levels was by radiocounting after HPLC. The data indicated a reduced conversion of GA12 to GA53 in dwarf plants, a difference which may be responsible for the dwarf morphology, although other explanations cannot be ruled out. Dwarf plants contained much less GA1, as measured by GC-MS. We did not detect differences in [14C]GA12 metabolism between plants grown under 10-h versus 16-h photoperiods, in either wild-type or dwarf plants, even though other wild-type plants contained less GA1, under short photoperiods than under long photoperiods.