In Vitro Organogenesis of a Slipper Orchid, Paphiopedilum ‘Alma Gavaert’

The aim of the present study was to improve the regeneration efficiency of callus lines in a slipper orchid, Paphiopedilum ‘Alma Gavaert’. Three kinds of vegetative tissues, root, stem and leaf segments, were used as explants to induce callogenesis; out of these, only root explants formed callus and was subcultured in the presence of 5 mg/L dicamba and 5 mg/L 2,4-D combined with 1 or 2 mg/L TDZ. The resulting four callus lines, assigned as 5Di1T, 5Di2T, 5D1T and 5D2T, respectively, were used to test the effect of NAA to BA ratios on re-differentiation, wherein the highest number of shoots (approximately 2 shoots/0.1 g callus clump) were obtained in callus line 5D2T at ratios of 0.001 and 0.002. A largely improvement of shoot regeneration efficiency was obtained by continuous selection of callus lines which derived from different explant positions. Eventually, six callus lines, including 5D2T-T6-G5 to 5D2T-T6-G10, were able to produce approximately 10 times of shoots per callus clump when compared with the parental callus line 5D2T.