An efficient micropropagation protocol for Monochasma savatieri Franch. ex Maxim through seed germination and direct shoot regeneration

Abstract

Monochasma savatieri Franch. ex Maxim is a valuable medicinal plant that is currently threatened due to human over excavation. Therefore, an efficient plant micropropagation protocol for M. savatieri through seed germination and direct shoot regeneration is described. The effects of different seed germination treatments, explant source on shoot induction, plant growth regulators on shoot multiplication, and survival rate of regenerated plants were examined. The highest M. savatieri seed germination rate was over 90% on Murashige and Skoog (MS) medium supplemented with 0.1 mg L−1 6-benzylaminopurine (6-BA) and 0.01 mg L−1 α-naphthaleneacetic acid (NAA), with the survival rate reaching 86.0% one-mo after transplanting to soil. Direct shoot proliferation was achieved with two explant types, but the use of nodal stem explants gave best results in comparison to shoot tip explants regarding shoot multiplication frequency and average number of shoots obtained per explant. For nodal segments, medium supplemented with 0.5 mg L−1 6-BA and 0.2 mg L−1 NAA gave the highest multiplication frequency of 90.0%. Among the various treatments tested for shoot multiplication, the best response occurred on MS medium containing 0.5 mg L−1 6-BA and 0.5 mg L−1 gibberellin (GA), with the number of shoots per explant reaching 27.6 and the average height of 4.25 cm. To obtain thick, elongated, and good quality buds, 6-BA at 0.1 and 0.5 mg L−1 along with 0.4 mg L−1 GA should be used interchangeably. Four-mo after transplantation, the survival rates were significantly affected by the types and concentrations of plant growth regulators used during plant tissue culture. The most effective combination of plant growth regulators 0.2 mg L−1 was 6-BA and 0.5 g L−1 ABT (mixture composed of 20% α-naphthaleneacetic acid content and 30% indole-3-acetic acid as active ingredients) with a survival rate of 85.5%. The in vitro propagation protocol for M. savatieri reported here will be useful for the rapid and large-scale propagation of this species.