Somatic embryogenesis and plant regeneration from a 700-year-old Kalopanax septemlobus tree

Abstract

We induced somatic embryogenesis and regenerated plants from the somatic tissues of a 700-year-old Kalopanax septemlobus tree. Embryonic calli were induced from juvenile tissues of grafted plants by pre-treating them with 1 M sucrose solution. Many normal plants were produced. Asexual propagation via somatic embryogenesis supports tree improvement programs. However, the induction of somatic embryogenesis from mature trees is still recalcitrant in many woody species with the exception of a few conifer and oak species. Previously, we developed a somatic embryogenesis protocol for a mature (40 years) Kalopanax septemlobus tree using rejuvenated tissues obtained by serial grafting. In the present study, we performed somatic embryogenesis and plant regeneration using a 700-year-old K. septemlobus tree. Calli were induced from young leaf and petiole explants of grafted plants by pre-treating them with 1 M sucrose solution. The induction rate of the embryogenic calli (EC) was less than 0.5%. However, the EC proliferated well and readily formed somatic embryos (SE), which were then converted to plantlets using routine protocols. The somatic EC did not differ from EC obtained from zygotic embryos with respect to SE formation, germination, and plant conversion. The genetic identities of regenerated plantlets were verified by comparison with the mother tree by chromosome counting, flow cytometry, and inter simple sequence repeat marker analysis.