PLANT REGENERATION AND CRYOPRESERVATION OF LILIUM

Abstract

Lilium is globally one of the most economically important ornamental crops used for flowers, medicine and food. Availability of efficient plant regeneration is necessary for micropropagation, genetic transformation, cryopreservation and production of virus-free plant material of Lilium. In this study, wide-spectrum protocols of plant regeneration via somatic embryogenesis from bulblet transverse thin cell layers (tTCLs) and via organogenesis from leaf segments were successfully established in Lilium. For somatic embryogenesis, 85.0, 75.3, 67.6, 27.8 and 25.0% of embryogenic callus induction frequencies (ECIFs) were obtained in five genotypes including L. longiflorum, L. longiflorum × Oriental 'Triumphator', L. Oriental hybrid 'Siberia', L. Asiatic hybrid 'Elite' and L. davidii var. unicolor, respectively. For organogenesis, similarly high shoot regeneration frequencies (SRFs) at 92-100% and a high number (4.7-7.0) of shoots per segment were obtained in 6 genotypes including L. Oriental hybrid 'Siberia', L. davidii var. unicolor, L. × formolongi, L. Asiatic hybrids 'Elite' and 'Pollyanna' and L. longiflorum × Oriental 'Triumphator'. Shoot tips of adventitious shoots derived from leaf segments of these Lilium genotypes were cryopreserved by droplet-vitrification. Shoot regrowth and somatic embryogenesis could be obtained in cryopreserved shoot tips, depending on post-culture conditions. Assessments of genetic integrity in regenerants from somatic embryogenesis, organogenesis and cryopreserved shoot tips by ISSR revealed that they were genetically stable. Data reported here have potential applications to genetic transformation, cryopreservation and production of virus-free plant material of Lilium by cryotherapy.