Optimization of in vitro propagation protocol of Dendrobium heterocarpum Wall. ex. Lindl. and clonal genetic fidelity assessment of the regenerates: An orchid of horticultural and medicinal importance
2022
Longchar, Temjennokcha B. | Deb, Chitta Ranjan
Dendrobium heterocarpum Wall. ex Lindl. (Orchidaceae) is an orchid having medicinal as well as ornamental values. The natural population of the species is downsized due to different anthropogenic activities. The present study was undertaken to standardize in vitro propagation technique of the species through immature embryo culture and optimizing different factors. Further, the study demonstrates the use of low cost substrata for hardening of in vitro regenerates. Immature embryos of 5–8 months after pollination (MAP) were cultured on three different media enriched with different organic carbon sources and four plant growth regulators at varied concentrations. The embryos of 8 MAP registered ∼95% germination on MS medium fortified with sucrose (3%, w/v), kinetin (3 μM/L). The resultant PLBs differentiated to young plantlets on the same initiation medium. Subsequently, the young plantlets proliferated and as many as ∼18 shoots were produced on MS medium containing sucrose and kinetin and α-naphthalene acetic acid (3 + 12 μmol/L) in combination. The regenerates were primary hardened by culturing on low cost substrata (coconut husk + wood bark at 1:1 ratio) fortified with 1/4th MS salt solution for one wk, subsequently maintaining to normal room temperature under 75% diffused light for ∼3–4 wk before transferring to potting mix. About 87% transplants survived post transfer. Clonal fidelity of the regenerants was also evaluated using RAPD, DAMD and SCoT markers. High degree of monomorphic percentage (96.89%) and low polymorphism (3.11%) was recorded between the mother plant and in vitro regenerates; thus, showing genetic homogeneity of the in vitro raised plants.
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