Establishment of an In Vitro Regeneration System Using Shoot Tips of Iris setosa

Iris setosa is a characteristic perennial wild herbaceous flower in the Changbai Mountain region of China, boasting significant ornamental and medicinal values. Given the increasing scarcity of its wild resources, this study developed an efficient in vitro regeneration system using shoot tips as explants via the direct organogenesis pathway. The optimal surface sterilization protocol was achieved with a treatment of 0.1% HgCl₂ for 8 min, resulting in an explant survival rate of 57.78%. The highest multiple shoot induction rate (88.89%) of shoot tips was achieved on MS medium supplemented with 2.0 mg·L⁻¹ 6-benzylaminopurine (6-BA), 0.5 mg·L⁻¹ naphthalene acetic acid (NAA), and 1.0 mg·L⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D). The optimal shoot differentiation and proliferation medium was MS + 2.0 mg·L⁻¹ 6-BA + 0.3 mg·L⁻¹ NAA, achieving a proliferation coefficient of 3.37. The optimal medium for rooting was confirmed to be 1/2 MS + 0.5 mg·L⁻¹ indole-3-butyric acid (IBA), exhibiting a high rooting rate reached 98.33%. During transplantation, plantlets exhibited high survival rates (over 90%) and vigorous growth across all three tested substrates, with no significant differences in survival rates among substrates. The key advance of this study lies in the development of a highly efficient and stable regeneration protocol for I. setosa derived from shoot tip explants, providing critical technical backing for the conservation and sustainable exploitation of its wild-type germplasm.