In vitro regeneration via indirect organogenesis from aseptic seedling-derived explants of the rare Tibetan medicinal shrub Sibiraea angustata

To conserve the germplasm resources of S. angustata and support its subsequent molecular biological research, this study aimed to establish efficient artificial propagation protocol. Using seeds of S. angustata as experimental materials, we investigated the effects of different medium formulations on seed germination, and further explored the impacts of various hormone ratios on its tissue culture via a complete factorial experimental design. The results showed that 1/4 MS was the optimal medium for both seed germination and seedling growth. Stem segments were more suitable as tissue culture explants than leaves. The optimal medium for stem segment callus induction was 1/4 MS + 1.0 mg·L⁻¹ 6-BA + 1.0 mg·L⁻¹ NAA (induction rate: 76.67%), for adventitious bud induction was 1/2 MS + 1.0 mg·L⁻¹ 6-BA + 0.1 mg·L⁻¹ NAA (induction rate: 83.33%), and for rooting induction was 1/4 MS + 1.0 mg·L⁻¹ IBA (average rooting rate: 80%; average root number: 6.83). This study successfully established a complete tissue culture and rapid propagation system for S. angustata , solving its rooting difficulty and providing technical support for the sustainable utilization, industrial seedling breeding, and introduction and domestication of this precious Tibetan medicinal plant.