A regeneration system using cotyledons and cotyledonary node explants of Toona ciliata

We used the cotyledons and cotyledonary nodes of Toona ciliata (Chinese mahogany) as explants to examine callus and adventitious shoot induction when exposed to different ratios of hormones. We also investigated the effects of seedling age, inoculation method, and genotype on the efficient regeneration of T. ciliata. The results showed that different genotypes exhibited significantly different callus induction efficiency. The cotyledons and cotyledonary nodes of 20-day seedlings inoculated onto MS medium with 0.5 mg/L 6-benzylaminopurine (6-BA), 0.5 mg/L kinetin (KT) and 0.05 mg/L 1-naphthylacetic acid (NAA) achieved a greater regeneration rate than did other concentrations of cytokinin and auxin. The numbers of shoots per cotyledon and cotyledonary node explant were 7.33 and 6.67. The optimal inoculation method for cotyledons was that the distal end of the explants was placed in contact with the medium. The optimal adventitious shoot differentiation medium for cotyledon explants was MS medium containing 0.3 mg/L 6-BA and 0.2 mg/L NAA, producing a 3.4 cm height of shoot on average. This study established an efficient regeneration system for T. ciliata with cotyledons and cotyledonary nodes as explants.