Hybridisation of Tarenaya
The spider flower, Tarenaya hassleriana (syn. Cleome hassleriana), belonging to the family Cleomaceae, originates from South America and is used as an ornamental plant. Cultivars like the 'Señorita' series show low genetic variation. Interspecific hybridisation should create new genetic variability. Therefore, tetraploid plants of the cultivar 'Señorita Blanca'® were open pollinated with Tarenaya hassleriana. In a second step, the hybrid T 8015 from this cross was open pollinated with Tarenaya boliviensis (syn. C. boliviensis). Forty-seven seedlings that arose from 100 seeds of mature capsules were cultivated directly under greenhouse conditions and showed intermediary morphological traits. To overcome insufficient seed development in the hybridisation process, in vitro cultivation of immature seeds was tested. Thus, 14 immature capsules were collected and surface sterilised by a diluted sodium hypochlorite solution (3% active chlorine) followed by threefold rinsing with autoclaved distilled water. Seeds were dissected under sterile conditions. Blind seeds were clearly discriminated and discarded. Remaining 74 seeds were cultivated on Murashige/Skoog medium supplemented with 5 g L⁻¹ polyvinyl pyrrolidone 10 in Petri dishes at 24°C and in dark conditions. After one week, a light exposure of 16 h alternated by 8 h darkness per day was applied. Seed germination started two weeks after sowing obtaining 30 seedlings. Twenty-two seedlings grew well and could be established as in vitro clone, four seedlings still remained in the callus phase and four seedlings died. Interspecific hybridisation was verified by RAPD analysis for the progeny in the greenhouse and in vitro culture. Flow cytometric analysis was applied to determine the ploidy level of the genotypes. Diploid and tetraploid genotypes were detected as well as genotypes with 2C values between diploid and tetraploid.