Enhancement in production of baicalein through transformation in Oroxylum indicum (L.) Vent by Rhizobium rhizogenes

Oroxylumindicum (L) Vent (O.indicum), a significant endangered medicinal plant, was transformed by the Rhizobiumrhizogenes (R.rhizogenes) mediated transformation method using the bacterial strain MTCC 532. For a successful transformation, factors such as explant selection, Co-cultivation time, temperature for induced root development, transformation technique, and antibiotic concentration were optimized. Various methods were employed for enhancing the rate of transformation. A drastic increase in transformation frequency was observed when CaCl2 was used in concentration of 10 mM and 15 mM along with ultrasonication during Co-cultivation. Total phenolic and flavonoid content was determined in various extracts of O.indicum by using Folin–Ciocalteau reagent and Aluminium chloride colorimetric method respectively. Moreover, the antioxidant potential of different extracts of O.indicum were assessed with the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method. Using specific rolA primers, molecular analysis was performed, revealing T-DNA integration in the hairy roots and confirming the expression of hairy root inducible genes. Murashige and Skoog (MS) medium with 3% sucrose was shown to have the maximum induction rate of hairy roots after 28 days of Co-cultivation. TLC as well as spectroscopic methods (UV–VIS and FTIR) were performed to compare the specific flavonoid (baicalein) in transformed roots as well as several non-transformed extracts. Comparing hairy roots to non-transformed roots, the total phenolic, flavonoid contents, and antioxidant activities were greater in hairy roots. The findings indicate that O.indicum hairy root cultures have a greater capacity for producing beneficial chemicals and researching their biological activities. The transformation of O.indicum by R.rhizogenes (MTCC 532) has been reported for the first time. © The Author(s) under exclusive licence to Society for Plant Research 2023.