In vitro propagation of the orchid Phalaenopsis circus via organogenesis and somatic embryogenesis using protocorm and thin cell layer explants

Orchids of the genus Phalaenopsis have high economic value in the floriculture industry and market and high potential for breeding programs. In vitro propagation makes it possible to clonally mass proliferate and conserve this valuable plant. In the current research, efficient protocols, some reported for the first time, for in vitro propagation of Phalaenopsis circus through organogenesis and somatic embryogenesis (SE) are presented. We used protocorms obtained from seeds and thin cell layers (TCLs) prepared from leaves as explants. Explants were cultured on Murashige and Skoog (MS) basal medium enriched with various concentrations and combinations of plant growth regulators. Protocorms were cultured on media fortified with 2,4-dichlorophenoxyacetic acid (2,4-D) in combination with N-phenyl-N´-1,2,3-thiadiazol-5-yl-urea (TDZ), and α-naphthalene-acetic acid (NAA) in combination with N 6 -furfuryl adenine or kinetin (Kin) for organogenesis, as well 2,4-D in combination with NAA for SE. These protocorms produced either protocorm-like bodies (PLBs) or somatic embryos. Results showed that the highest number of PLBs (75.0) was obtained on medium enriched with 1.0 mg l –1 2,4-D. Maximum number of somatic embryos (12.3/explant) was obtained on medium containing 0.5 mg l –1 2,4-D together with 2.0 mg l –1 NAA. The use of transversal TCLs with 2–3 cell layers as explants cultured on medium supplemented with 0.5 mg l –1 IBA combined with 1.0 mg l –1 TDZ produced the highest number of plantlets. Plantlets were transferred to pots and acclimatized in ambient greenhouse conditions with 100% survival rate.