One-month-old Paphiopedilum delenatii Guillaumin shoots in approximately 1.5–2.0 cm length derived from ex vitro grown plants in a greenhouse (under the natural light no more than 200 lmol m-2 s-1 with sunshade nets, at 16–25 C, and 60–90 % relative humidity) at the Tay Nguyen Institute for Scientific Research were used as initial explant source (Fig. 1a1,a 2).