Improved Floral Characteristics of Tetraploid Stephanotis

The stephanotis plant, Marsdenia floribunda (Brongn.), is an evergreen climber native to Madagascar that is cultivated in tropical and subtropical regions for its white fragrant flowers.  In Hawaii, M. floribunda flowers are strung as lei lengthwise, requiring about 25 flowers, or they are pierced through the side of the corolla, utilizing up to 700 flowers, depending on style. A cultivar possessing larger flowers, such as a tetraploid form, would be beneficial to the lei industry, since fewer flowers would be required to produce a lei.  The objective of this experiment was to create a tetraploid M. floribunda by treating seeds with colchicine. Seeds were treated in a 0.0%, 0.05%, 0.1%, 0.2%, or 0.4% colchicine solution for 24 or 36 hours before sowing in moist peat–perlite media. Based on visual inspection, suspected tetraploid seedlings were selected for screening using stomatal guard cell measurements, since guard cells of polyploid plants are usually larger than those of diploid plants of the same species. Four plants were identified as possible polyploid plants based on guard cell measurements. Flow cytometric analysis was used to confirm the ploidy status of the 4 candidates, with 1 being diploid, 2 mixoploid and 1 tetraploid. The tetraploid plant has produced flowers about 33% wider, and with the corolla tube about 50% longer than the diploid control.