Analysis of regeneration protocols for micropropagation of Pterocarpus santalinus

A micropropagation is a powerful tool in the era of the biotechnology revolution. It has a broad range of potentiality as compared to conventional vegetative propagation attracting researchers, industrialists, governmental and nongovernmental organizations at the national and international level. The potential methods of organogenesis and somatic embryogenesis, primarily through callogenesis, allow the production of genotypically identical and pharmacologically conserved disease-free healthy stocks in shorter times. Pterocarpus santalinus, the pride of Andhra Pradesh, has become endangered due to medicinal and commercial overexploitation. The micropropagation of P. santalinus poses many cultural challenges due to limited regeneration potential through callogenesis, organogenesis, and somatic embryogenesis. The lack of proper explant treatment and the effect of plant growth regulators limit the application of published protocols to reproduce the results. The challenge, such as heavy contamination of mature explants with endophytic fungi, forced us to explore the potential of immature tissues for regeneration through induction of somatic embryogenesis. We observed that immature tissues (zygotic embryo, petal, ovary, and anther) are better responsive than mature tissues with the scantiest contamination and phenolic release. The present study analyzed, evaluated, and interpreted the different parameters applied in the micropropagation of P. santalinus. The aim is to solve the discrepancies of existing protocols to present complete insight for future needs in the successful regeneration of the species. The review also compared various treatments to overcome dormancy and promote germination. It also discussed the possibilities of induction of somatic embryogenesis for future research.