title: Vitrification-based cryopreservation of protocorm-like bodies of an endangered lady's slipper orchid: Paphiopedilum niveum (Rchb.f.) Stein.
abstract: BACKGROUND
  Paphiopedilum niveum (Rchb.f.) Stein, an endangered lady's slipper orchid, is listed in CITES Appendix I and thus requires conserving.
  
  
  OBJECTIVE
  The study aimed to cryopreserve protocorm-like bodies (PLBs) by a vitrification technique.
  
  
  METHODS
  Four-month-old PLBs were precultured in modified Vacin and Went liquid medium with various sucrose concentrations for 24 h and 5 d with daily increasing sucrose concentrations followed by different exposure times to plant vitrification solution 2 (PVS2).
  
  
  RESULTS
  Precultured PLBs in 0.75 M sucrose for 5 d with stepwise increase of sucrose and PVS2 for 90 min provided the highest viability after drying to low moisture content. The cryopreserved PLBs exhibited fewer dark stained nuclei and accumulated starch grains than those of the control. Cryopreserved PLBs had some shrunken epidermal cells, no change in ploidy level, a survival level of 22 % and the regenerated plantlets grew well.
  
  
  CONCLUSIONS
  This study is the first report evaluating the success of cryopreserved PLBs of P. niveum via a vitrification protocol.
authors.affiliation: Department of Biology, Faculty of Science, Prince of Songkla University, Hat-Yai, Thailand.
authors.forename: Supornchai
authors.initials: S
authors.lastname: Chaireok
authors.affiliation: Department of Plant Science, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Kanchit
authors.initials: K
authors.lastname: Thammasiri
authors.affiliation: Department of Biology, Faculty of Science, Prince of Songkla University, Hat-Yai, Thailand. upatham.m@gmail.com.
authors.forename: Upatham
authors.initials: U
authors.lastname: Meesawat
mesh_terms: D015925:Cryopreservation / Q000379:methods*; D056727:Endangered Species; D029595:Orchidaceae / Q000196:embryology; D013778:Tetrazolium Salts / Q000737:chemistry; D058989:Vitrification
chemical_list: D013778:Tetrazolium Salts; C009591:triphenyltetrazolium