Microclonal propagation of the orchid Vanda (Orchidaceae Vanda)

Biotechnological methods of propagation of Vanda orchids represent an effective approach for obtaining large quantities of genetically uniform and disease-free plant material. This study aimed to investigate the specific features of microclonal propagation of Vanda orchids. To obtain planting material of different Vanda genotypes, namely ‘Vanda coerulea’ and ‘Vanda sanderiana’, direct and indirect morphogenesis, as well as in vitro rhizogenesis followed by adaptation to in vivo conditions, were applied. A stepwise method for obtaining aseptic material was developed, involving treatment with 70% ethyl alcohol for 1 minute followed by the application of the main sterilising agent, 2.5% NaClO, for 5-10 minutes. This protocol made it possible to obtain 70%-80% sterile and viable explants while reducing the level of fungal and bacterial contamination. The results of direct and indirect morphogenesis, callus formation, and rhizogenesis in in vitro cultures of Vanda explants are presented. No significant differences in callus formation were observed between the studied cultivars. The frequency of callusogenesis for both genotypes reached 100%, indicating a high capacity for callus tissue formation. The best results in growth and shoot formation were achieved on Murashige and Skoog (MS) nutrient medium supplemented with 0.5 mg/L 6-benzylaminopurine (6-BAP). For rooting, the most effective medium was MS with half‑strength macro- and microelements supplemented with 0.5 mg/L α-naphthaleneacetic acid (NAA). This medium is recommended for the induction of rhizogenesis in regenerated plants of different Vanda cultivars. For the adaptation of regenerated plants, a substrate composed of sphagnum moss, peat, crushed beech leaves, and pine bark in a ratio of 1:1:1:1 was used. The survival rate of ‘Vanda coerulea’ plants under in vivo conditions reached 87.5%, whereas under the same conditions, the survival rate of ‘Vanda sanderiana’ plants was 83%. The obtained results may serve as a basis for the development of propagation protocols for Vanda orchids, ensuring a high level of control at all stages of cultivation. The implementation of such protocols is important for breeding programmes, the conservation of rare cultivars, and the improvement of plant material quality for commercial floriculture