Hemidesmus indicus L. Br.: critical assessment of in vitro biotechnological advancements and perspectives.

Hemidesmus indicus (L.) R. Br. ex Schult., commonly known as Indian sarsaparilla or Anantamul, is an ethnopharmacologically important medicinal plant from the family Apocynaceae. Biosynthesis of an array of bioactive compounds such as methoxybenzaldehydes and their derivatives has been accountable for its intensive medicinal attributes. Low seed setting, over-exploitation from natural habitat and a need for selection and preservation of elite germplasms yielding higher levels of bioactive compounds have led researchers to enquire the standardization of micropropagation techniques and quantitative estimation of phytochemicals from H. indicus. The present work aims to have a comprehensive account on micropropagation in H. indicus, a comparative estimation of biotic and abiotic factors, viz. elicitors and precursors playing a crucial role in H. indicus tissue culture, a critical appraisal of applied protocols to nullify embellished claims and a discussion on future perspectives. The review also highlights the comparative effect of different plant growth regulators as well as their combined role in rhizogenesis, callogenesis, base callus formation, callusing and somatic embryo-mediated indirect organogenesis, outcome of explant selection, contribution of abiotic (temperature, photoperiod, moisture, inorganic molecules) factors, role of carbon source, application of sterilization techniques and associated success rates, role of factors essential for acclimatization and secondary metabolite production, synthetic seed production and genetic transformation techniques. The compiled information along with individual study details, respective outcome and variability of reports will aid in proper assessment of cited standardized tissue culture protocols in H. indicus especially in relation to secondary metabolite production. Moreover, the assessment of applicability of different methodologies in this aspect will aid in the selection of high-yielding germplasms or chemotypes which is not only profitable for industrial application but also important for basic and applied preclinical and clinical research studies. KEY POINTS: • Critical and updated assessment on in vitro biotechnology in Hemidesmus indicus. • Biotechnological advancement via Agrobacterium-mediated transformation. • Key shortcomings and future research directions Graphical abstract Effect of biotic and abiotic factors on Micropropagation and secondary metabolite synthesis in Hemidesmus indicus.