Micropropagation and Assessment of Genetic Homogeneity in Dendrobium chryseum

Abstract

Dendrobium chryseum, an epiphytic orchid has high horticultural and medicinal value. The present study was carried out to develop the efficient propagation technique of D. chryseum, from in vitro culture microshoots and to evaluate the genetic homogeneity between in vitro regenerated plantlets using a molecular markers system i.e., RAPD and ISSR. In present investigation, in vitro raised micro shoots were used as explants (approximately 0.5-1 cm) induced from protocorm on half strength MS media fortified with 2 mg/L of Kn and 10% CW. Different strength of agar solidified MS medium with or without fungal elicitors [Coniochaeta africana (R3) and Coniochaeta dendrobiicola (R7)], adenine sulphate, coconut water, and hormones like BAP (6-Benzyl Amino Purine), NAA (α-Naphthalene Acetic Acid), IAA (Indole-3-Acetic Acid), Kn (Knetin) and IBA (Indole-3-Butyric Acid) were used for induction of shoots and roots. Young, healthy leaves derived from wild plants (same plant capsule was used for in vitro culture) and in vitro raised plantlets were used as explants for DNA isolation. Among the tested medium, the best condition for D. chryseum for shoot number was on full strength MS medium fortified with 15% CW (6.25 ± 0.50) per microshoot which is followed by half strength MS medium fortified with fungal elicitor 0.5% R3 (5.75 ± 0.50) per microshoot. Similarly the most suitable medium for D. chryseum for root number was on full strength MS medium fortified with 15% CW (9.75 ± 0.50) per shoot which is followed by half strength MS medium fortified with fungal elicitor 0.5% R3 (8.25 ± 0.50) per shoot. The most appropriate medium for shoot length of for D. chryseum was on full strength MS medium fortified with 15% CW (6.7 ± 0.14 cm) which is followed by full strength MS medium fortified with fungal elicitor 1% R3 (5.37 ± 0.15cm). Similarly the most appropriate medium for root length of for D. chryseum was on full strength MS medium fortified with 15% CW (6.3 ± 0.11cm) which is followed by full strength MS medium fortified with fungal elicitor 1% R3 (5.55 ± 0.20cm). Similarly high degree genetic homogeneity was found among and within the mother and in vitro regenerated plantlets of D. chryseum analyzed by using RAPD and ISSR markers. Hence, the present research showed no genomic alternation in regenerated plantlets supporting the efficiency of the protocol for obtaining clonally stable true-to-type plantlets and conservation of a threatened medicinal orchid.