Direct regeneration and Genetic transformation studies in Hemidesmus indicus (L.) R. Br. (Indian Sarasaprilla)

Abstract Since ages, plants continue to provide new remedies to mankind. Hemidesmus indicus L. R. Br. is one such plant belonging to family Apocynaceae, showing potent medicinal properties known through traditional knowledge. Hemidesmus is also explored for the presence of flavoring compound namely 2-hydroxy-4-methoxybenzaldehyde (HMB) which is used in pharmaceutical and nutraceutical industries. Due to anthropogenic activities, the plant has been exploited till the ridge for its ethnobotanical properties for mankind. Biotechnological intervention to conserve this endangered sps through in vitro plant cultures, micropropogation and genetic transformation studies is the pre-requite to maintain it from extinction. The objective of the study is to improve the regeneration potential and optimize the genetic transformation in Hemidesmus indicus. The direct regeneration of Hemidesmus indicus through leaf explants, nodal explants with subsequent plant regeneration using Murashige and Skoog (MS) medium supplemented with various plant growth regulators (auxins, cytokinins, and gibberellic acid), adenine sulphate, TRIA. The Agrobacterium tumefaciens mediated genetic transformation studies in Hemidesmus indicus was carried out in callus cultures using the plant expression vector pCAMBIA 1301. The caulogenic response of 78.8%, 73.3% and 71.4% was observed when the leaf explant was inoculated on MS media containing 2.3 mgL− 1 BAP + 0.2 mgL− 1 2,4-D, 0.02 mgL− 1 TRIA + 2 mgL− 1 BAP, 1 mgL− 1 KIN + 1 mgL− 1 NAA respectively with creamish yellow nodular friable callus by the 4 weeks. The initiation of shoot bud was observed within three days after inoculation of nodal explant on media supplemented with 1 mgL− 1 BAP + 0.1 mgL− 1 NAA, 1 mgL− 1 BAP + 0.1 mgL− 1 NAA + 40 mgL− 1 AgNO3, 1 mgL− 1 BAP + 0.1 mgL− 1 NAA + 40 mgL− 1 AgNO3 + 40 mgL− 1 adenine sulphate respectively and incubated in the dark for 2 weeks. Shoot regeneration from the leaf explants was also observed within 4 weeks after inoculation in MS medium with 1 mgL− 1 BAP + 0.1 mgL− 1 NAA. Agrobacterium mediated genetic transformation was carried out successfully in callus cultures of H. indicus. The transformation efficiency was found to be 26%. The efficient shoot regeneration was observed within 4 weeks and transformation study can be further applied for over expression of biosynthetic genes to enhance the bioactive components that have immense significance in pharmaceutical, nutraceutical and cosmetic industries.