낙엽송 성숙목의 액아배양을 통한 식물체 재분화

Plant regeneration from axillary buds of mature Larix kaempferi trees

Using multiple-shoot induction and shoot elongation, this study established an in vitro propagation method for mature Larix kaempferi. Axillary bud explants were cultured on Schenk and Hildebrandt (SH), Litvay (LM) and Quoirin and Lepoivre (LP) media supplemented with various concentrations of 6-benzylaminopurine (BA) (0, 0.2, 0.5, 2.0, and 5.0 mg L-1) to evaluate multiple-shoot induction. The highest number of shoots per explant (2.9 ± 0.2) was obtained for an SH medium containing 0.5 mg L-1 of BA. Contrastingly, a hormone-free SH medium promoted the greatest shoot elongation (23.0 ± 1.1 mm) after six weeks of culture. The effect of gibberellic acid (GA3) on shoot elongation was also examined. GA3 treatment significantly increased shoot length, with the maximum elongation (15.0 ± 0.1 mm) observed at a GA3 concentration of 0.5 mg L-1 after three weeks of culture. However, a higher concentration (2.0 mg L-1) resulted in abnormal shoot morphology, with an abnormality rate of 33.3 ± 10.9%, and was associated with reductions in the contents of chlorophyll-a and chlorophyll-b. Root induction achieved using various auxins indole-3-butyric acid (IBA), indole-3-acetic acid (IAA) and 1-naphthaleneacetic acid (NAA) was largely unsuccessful owing to excessive callus formation and shoot necrosis. In addition, limited rooting was achieved by a half-strength SH medium containing 2.0 mg L-1 of IBA (6.6 ± 3.3%). Overall, the findings indicate that 0.5 mg L-1 BA is optimal for multiple-shoot induction, while 0.5 mg L-1 GA3 enhances shoot elongation. Although rooting efficiency remained low, the partial root induction demonstrated the potential applicability of this method for the clonal propagation of elite L. kaempferi genotypes.