An efficient, highly reproducible protocol for multiple shoot induction and plant regeneration of Pongamia pinnata has been successfully developed using cotyledonary node explants. This study also demonstrates that preconditioning of explant stimulates production of multiple shoots from cotyledonary nodes of P. pinnata. The highest direct shoot regeneration (90%) with an average of 18.4 ± 3.1 shoots/explant were obtained when cotyledonary node explants were excised from seedlings germinated on Murashige and Skoog (MS) media supplemented with benzyladenine (BA) 1 mg l -1 , and subsequently cultured on MS media with 1 mgl -1 thidiazuron (TDZ). Scanning electron microscope observations of cotyledonary node (CN) explants excised from pre-conditioned and normal seedlings, revealed larger buds with rapid development in BA-preconditioned CN explants. The addition of adenine sulphate significantly increased the average number of shoots per explant. The highest direct shoot regeneration (93%) with an average of 32.2 ± 0.93 shoots/explant was obtained from BApreconditioned CN when cultured on MS media supplemented with 1 mg l -1 TDZ and 200 mg l -1 adenine sulphate (ADS). Repeated shoot proliferation was observed from BA preconditioned CN explants up to 3 cycles with an average of 15 shoots/explant/cycle when cultured on MS media supplemented with 1 mgl -1 TDZ and 150 mg l -1 L-glutamine, thus producing 45 shoots/CN explant. Shoots were elongated on hormone free MS media and rooted on ½ MS media supplemented with 1 mg l -1 of IBA. Rooted shoots were successfully acclimatized and established in soil with 80% success. The highly regenerative system developed in this investigation for this important tree could be a useful tool for genetic transformation.

Flavonoids have aroused considerable interest because of their potential beneficial effect on human health. Quercetin is one of the most abundant natural flavonoids present in medicinal plants. In the present study, a comparative phytochemical analysis of bioactive compounds from leaf and leaf derived callus of Abutilon indicum L. was carried out. Thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) analysis of methanolic extract of Abutilon leaf revealed the presence of quercetin. To test the effect of precursor in enhancing flavonoid content, in vitro studies were conducted by supplementing phenylalanine to actively growing callus cultures of Abutilon. More than threefold increase in quercetin content was obtained in elicitor induced callus compared to control.