Vol.:(0123456789) 1 3 Vegetos https://doi.org/10.1007/s42535-023-00602-8 RESEARCH ARTICLES Enhancement in production of baicalein through transformation in Oroxylum indicum (L.) Vent by Rhizobium rhizogenes Rumana Faraz 1  · Mamta Gokhale 2  · Ragini Gothalwal 3 Received: 17 March 2022 / Revised: 15 February 2023 / Accepted: 25 February 2023 © The Author(s) under exclusive licence to Society for Plant Research 2023 Abstract Oroxylum indicum (L) Vent (O. indicum), a signifcant endangered medicinal plant, was transformed by the Rhizobium rhizo- genes (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 CaCl 2 was used in concentration of 10 mM and 15 mM along with ultrasonication during Co-cultivation. Total phenolic and favonoid 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 diferent extracts of O. indicum were assessed with the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method. Using specifc rolA primers, molecular analysis was performed, revealing T-DNA integration in the hairy roots and confrming 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 specifc favonoid (baicalein) in transformed roots as well as several non-transformed extracts. Comparing hairy roots to non-transformed roots, the total phenolic, favonoid contents, and antioxidant activities were greater in hairy roots. The fndings indicate that O. indicum hairy root cultures have a greater capacity for producing benefcial chemicals and researching their biological activities. The transformation of O. indicum by R. rhizogenes (MTCC 532) has been reported for the frst time. Keywords Rhizobium rhizogenes · Hairy roots · Oroxylum indicum · Flavonoid · UV–VIS spectroscopy · FTIR Introduction Oroxylum indicum (L) Vent of family Bignoniaceae, is a medicinally important plant bearing vital secondary metabolites. It is an endangered medicinal tree species, which possesses several antimicrobial, antiarthritic, anti- hepatic qualities in its various parts (Laupattarakasem et al. 2003; Begum et al. 2019). Parts of the tree are often used to cure infammation, dropsy, bronchitis, jaundice, piles, smallpox, leucoderma, scabies, enlarged spleen, hel- minthiasis, gastropathy, hemorrhoids, cholera and rheuma- toid arthritis (Bansal and Gokhale 2012). Root of the tree has long been used in Ayurveda for preparation of Amar- tarista, Awalwha, Brahmarasayana, Chyawanaprasha, Dantyadarishta, Dhanawantaraghrita, Mulayadikwath, Narayanataila, Shyonaka patpak, Bruhatpanchamulaya dikwath and Dashmularisht (Singh 2015). O. indicum is characterized by brown bark and large pinnate leaves. Oroxylum is a genus of medium sized, deciduous trees, distributed in India, Sri Lanka, Malaysia, China, Thailand, Philippines and Indonesia. In India, the tree is indigenous to Eastern and Western Ghats and is also found in North- East regions (Ahad et al. 2012). O. indicum is commonly known as “Indian Trumpet tree” due to its resemblance to trumpet. The plant is known for its high commercial and * Rumana Faraz rfaraz82@gmail.com 1 Department of Biotechnology, St. Aloysius (Autonomous) College, Sadar Cantt, Jabalpur, Madhya Pradesh 482001, India 2 Department of Botany and Microbiology, St. Aloysius (Autonomous) College, Sadar Cantt, Jabalpur, Madhya Pradesh 482001, India 3 Department of Biotechnology, Barkatullah University, Hoshangabad Road, Bhopal, Madhya Pradesh 462026, India