Interspecific hybridization between Hibiscus syriacus L. and Hibiscus paramutabilis Bailey

Different Hibiscus syriacus L. cultivars (diploid 'Melwhite' and 'Oiseau Bleu' and tetraploid 'Red Heart cv' and 'Purple cv') were used in a breeding program with Hibiscus paramutabilis Bailey. Compared to Hibiscus syriacus, a well-known winter hardy ornamental shrub, Hibiscus paramutabilis grows more vigorously, with larger leaves and flowers. When used as a seed parent, H, paramutabilis failed to set fruits. However, when pollinated by H. paramutabilis, H.s. 'Oiseau Bleu' and H.s. 'Red Heart cv' reacted by fruit setting. Fruits containing swollen (=fertilized) ovules were not observed on H.s. 'Melwhite' or H.s. 'Purple cv'. After putting the isolated embryos in vitro 5 H.s. 'Red Heart cv' x H. paramutabilis embryos and 7 H.s. 'Oiseau Bleu' x H, paramutabilis embryos could be converted. Respectively 1 and 6 plants were acclimatized and put in soil; they grew vigorously and leaves of all showed strong morphological similarities with H. paramutabilis. Ploidy analysis of these potential hybrids revealed that the H.s. 'Red Heart cv' offspring was triploid, as was expected. AFLP analysis confirmed the hybrid character of all tested seedlings.