Direct regeneration, microshoot recovery and assessment of genetic fidelity in Helicteres isora L., a medicinally important tree

Abstract

Abstract Helicteres isora L., is an endangered valuable medicinal tree species. Direct shoot regeneration was initiated from cotyledonary node (CN) and axillary nodal explants (AN) of in vitro raised seedlings using the plant growth regulators (PGRs) and organic additives. A combination of 4.92 μM N6- (2- isopentenyl) adenine (2iP), 9.08 μM thidiazuron (TDZ) and 2.69 μM naphthaleneacetic acid (NAA) in Murashige and Skoog (MS) medium resulted with 16.1 and 11.4 shoots from CN and AN explants respectively. Maximum shoot numbers (CN: 21.3; AN: 16.9) were recorded by addition of 342.1 μM glutamine with 4.92 μM 2iP, 9.08 μM TDZ and 2.69 μM NAA combination. Basal callus associated shoot regeneration problems were successfully overcome through altering sucrose concentration (20 g l−1) in culturing media. Pre-treated microshoots were elongated (10.9 and 9.8 cm) when cultured on half-strength MS medium fortified with a combination of 4.92 μM 2iP and 1.44 μM gibberellic acid (GA3). Elongated shoots were best rooted (12.9 per shoot), in half-strength MS medium containing 4.90 μM indole-3-butyric acid (IBA). Plantlets were successfully acclimatised (71.4%) in poly tunnel chamber. Genetic homogeneity was successfully confirmed by SCoT and ISSR marker systems. In both techniques 63 and 27 monomorphic bands were resolved from SCoT and ISSR primers respectively. Developed micropropagation protocol could be a reliable method for clonal propagation of H. isora.