Huijing Zhou

Camptotheca acuminata produces valuable camptothecin, a potent anticancer agent. To overcome the limitations of wild resources, we developed efficient in vitro regeneration and camptothecin production systems. Key findings include: Optimal sterilization of plant material was achieved using Plant Preservative Mixture (12 min). Axillary shoot induction was most effective on MS medium with 2.5 mg/L 6-BA and 0.25 mg/L NAA, while adventitious shoot regeneration showed a preference for 1 mg/L 6-BA and 0.1 mg/L NAA. Synchronous induction reached its peak at 83.45% using MS medium with 0.5 mg/L 6-BA, 0.05 mg/L NAA, and 0.5 mg/L GA₃. Shoot elongation benefited from 5 mg/L phloroglucinol and 20 mg/L CaCl₂. For biomass production, 2/3 MS macroelements yielded maximum adventitious shoot biomass (50.52 mg). Rooting reached 100% efficiency on 1/2 MS medium containing 1 mg/L IBA, 0.5 mg/L NAA, 5 mg/L phloroglucinol, and 2 g/L AC, averaging 10.50 roots per shoot. The four-stage camptothecin enrichment system produced shoots containing 795.10 µg/g DW camptothecin—fivefold higher than natural leaves. This breakthrough establishes: (1) the first in vitro camptothecin enrichment platform; (2) a sustainable alternative to wild harvesting; (3) a novel circular production model for endangered medicinal plants. The optimized protocols address the challenges of camptothecin supply while demonstrating remarkable productivity enhancements through controlled in vitro culture systems.

Triadica sebifera, an economically and medicinally valuable tree species native to China, was investigated for its in vitro regeneration potential using leaf explants from nodal cuttings of young stems and sprouts. This study evaluated the effects of basal media, plant growth regulators (PGRs), explant sources, and incision methods on adventitious shoot induction, supplemented by histological analysis. The highest shoot regeneration frequency (98.89%) and maximum shoot number (72) were achieved via direct organogenesis using sucker-derived nodal cuttings cultured on MS medium with 2 mg/L 6- benzyladenine (6-BA), 0.3 mg/L kinetin (KT), and 0.2 mg/L α-naphthaleneacetic acid (NAA). Under identical conditions, branch-derived explants showed lower regeneration (84.44%, 64 shoots). Transverse midvein incision proved most effective, with sucker-derived leaves exhibiting superior regeneration. Shoots elongated completely (100%) on Murashige and Skoog (MS) medium containing 0.3 mg/L 6-BA, 0.03 mg/L NAA, and activated charcoal. Rooting was optimal on MS medium with 0.3 mg/L indole-3-butyric acid (IBA), yielding a 98% acclimatization survival rate. Histological analysis revealed de novo meristem formation from parenchyma cells, confirming direct organogenesis without callus intermediation, further validating the enhanced regenerative capacity of sprout-derived explants. This efficient in vitro regeneration system provides a foundation for large-scale propagation and germplasm conservation of T. sebifera, while offering insights for woody plant regeneration studies.

Mango (Mangifera indica L.) is one of the most significant tropical and subtropical fruit species, with high ecological and economic value. However, research on the in vitro culture of mangoes is relatively weak, so establishing an efficient and stable mango plant regeneration system is of great significance. In this study, a preliminary mango regeneration system was established with Mangifera indica L. cv. Keitt from young branches as the starting explants. The results showed that the optimal plant growth regulator (PGR) formula for direct adventitious shoot induction on the branches was 1 mg/L 6-benzylaminopurine (6-BA) + 0.1 mg/L a-naphthaleneacetic acid (NAA), with an adventitious shoot induction rate of 73.63% and an average of 6.76 adventitious shoots. The optimal basal medium for adventitious shoot induction was wood plant medium (WPM), with an adventitious shoot induction rate of 63.87% and an average of 5.21 adventitious shoots. The optimal culture medium for adventitious shoot elongation was WPM + 1 mg/L 6-BA + 0.5 mg/L NAA, with an adventitious shoot elongation rate of 89.33% and an average length of 5.17 cm. The optimal formula for the induction of mango rooting was Douglas fir cotyledon revised medium (DCR) + 3 mg/L indole-3-butyric acid (IBA), with a maximum rooting rate of 66.13% and an average rooting quantity of 6.43. The genetic fidelity of the in vitro-regenerated plants was evaluated using inter-simple sequence repeat (ISSR) molecular markers. There was no difference between the in vitro-regenerated plants and the parent plant. This study provides an efficient and stable propagation system for Mangifera indica L., laying the foundation for its rapid propagation and genetic improvement.