Renanthera imschootiana Rolfe is an endangered tropical epiphytic orchid that is threatened with extinction due to overcollection and the loss of suitable habitats. In vitro propagation is a useful way to mass produce plants for re-establishment in the wild and for commercial propagation. Seeds collected 150 days after pollination (DAP) were the optimum stage for in vitro culture. Seed germination reached 93.1% on quarter-strength MS (i.e., MS containing a quarter of macro- and micronutrients) medium containing 0.5 mg l -1 α-naphthaleneacetic acid (NAA), 20% coconut water (CW), 1.0 g l -1 peptone, 10 g l -1 sucrose and 1.0 g l -1 activated charcoal (AC). Quarter-strength MS medium supplemented with 1.0 mg l -1 BA, 0.5 mg l -1 NAA, 1.0 g l -1 peptone, 10 g l -1 sucrose and 20% CW was suitable for the sub-culture of protocorm-like bodies (PLBs) in which the PLB proliferation ratio was 2.88. Quarter-strength MS medium containing 1.0 mg l -1 NAA, 1.0 g l -1 peptone, 100 g l -1 banana homogenate (BH), and 1.0 g l -1 AC was suitable for plantlet formation and 95.67% of plantlets developed from PLBs within 60 days of culture. Hyponex N016 medium supplemented with 0.5 mg l -1 NAA, 1.0 g l -1 peptone, 20 g l -1 sucrose, 150 g l -1 BH, and 1.0 g l -1 AC was suitable for the in vitro growth of plantlets about 2-cm in height. Plantlets 3-cm in height or taller were t ransplanted to Chilean sphagnum moss, and 95% of plantlets survived after 60 days in a greenhouse. Three hundred transplanted of seedlings 360-days old were reintroduced into three natural habitats. Highest percentage survival (79.67%) was observed in Yuanjiang Nature Reserve two years after reintroduction, followed by Huolu Mountain forest park (71.33%). This protocol is an efficient means for the large-scale propagation and in vitro and in vivo germplasm conservation of R. imschootiana.
Wu, K., Zeng, S., Lin, D., Da Silva, J. A. T., Bu, Z., Zhang, J., & Duan, J. (2014). In vitro propagation and reintroduction of the endangered renanthera imschootiana rolfe. PLoS ONE, 9(10). https://doi.org/10.1371/journal.pone.0110033