Paphiopedilum niveum (Rchb.f.) Stein, an endangered species, has been listed in CITES Appendix I and its germplasm conservation is required. To improve the regeneration of cryopreserved somatic embryos (SEs), adding 0.1 mM ascorbic acid (AsA) at a critical step during cryopreservation was investigated. The reactive oxygen species (ROS) and malondialdehyde (MDA) contents were also assessed during five steps (preconditioning, 1^st preculture, 2^nd preculture, osmoprotection, and dehydration) of a developed V cryo-plate technique as described briefly. Two-month-old SEs were preconditioned on modified Vacin and Went medium (MVW) containing 0.1 M sucrose for seven days. These SEs were precultured on MVW containing 0.2 M sucrose for one day (1^st preculture) before being transferred to the same medium with 0.6 M sucrose for one day (2^nd preculture). Precultured SEs were embedded on a cryo-plate, incubated in loading solution (LS) with 1.2 M sucrose for 30 min at 25°C and dehydrated with plant vitrification solution 2 (PVS2) for 60 min at 25°C. It was found that applying AsA on day 7 after culture (before the 1^st preculture) could reduce total ROS and MDA levels, leading to a high regeneration percentage (39%) of cryopreserved P. niveum SEs.

濒危物种兜兰（Rchb.f.）Stein已列入CITES附录I，必须对其种质进行保护。为了提高冷冻保存的体细胞胚（SEs）的再生，研究了在冷冻保存的关键步骤添加0.1 mM抗坏血酸（AsA）。简要介绍了已开发的V型冷冻板技术的五个步骤（预处理，第^一次预培养，^第二次预培养，渗透保护和脱水），还评估了活性氧（ROS）和丙二醛（MDA）的含量。两个月大的SE在含有0.1 M蔗糖的改良Vacin和Went培养基（MVW）上预处理7天。这些的SE预培养于含有0.2M蔗糖的一天（1 MVW ^ST预培养），然后再转移到含0.6 M蔗糖的同一培养基中一天（^第二次预培养）。将预培养的SE包埋在冷冻板上，在25°C下与1.2 M蔗糖的上样溶液（LS）中孵育30分钟，并在25°C下用植物玻璃化溶液2（PVS2）脱水60分钟。发现在培养后第7天（第^一次预培养之前）施用AsA可以降低总ROS和MDA水平，从而导致冷冻保存的P. niveum SEs的再生百分率高（39％）。