Comparative analysis on the effect of trimethoprim and bavistin on direct shoot regeneration in Brahmi (Bacopa monniera) in growth regulator free MS medium

Leaf, node and internode explants of Brahmi (Bacopa monniera L. were cultured on growth regulators free (GR free) MS basal medium to assess the effect of an antibiotic (Trimethoprim-TMP) and an antifungal agent (Bavistin-BVN). Direct shoot regeneration without callus formation was induced by culturing different explants on GR free MS medium at lower concentration of TMP. TMP (antibiotic agent) at 50 mg l^sup -1^ was found optimum for shoot regeneration from leaf explants, while higher concentration of TMP did not show any improvement on more than 50 mg l^sup -1^ for shoot regeneration in node explants. BVN (antifungal agent) at 100 mg l^sup -1^ had the optimum effect on regeneration from inter-node and leaf explants, but node explants showed better regeneration on 150 mg l^sup -1^ BVN. The adventitious shoot regenerated from vertically placed nodes on medium containing 150 mg l^sup -1^ BVN and horizontally placed node segments showed regeneration at 100 mg l^sup -1^. Increasing upto 200 mg l^sup -1^ TMP concentration significantly promoted adventitious shoot bud regeneration in inter-modal explants. The combination of TMP and BVN significantly suppressed root regeneration at higher concentration in internodes and leaf explants, whileTMPat lower concentration showed better root regeneration as compared to culture grown on GR-free MS-medium. Trimethoprim and Bavistin exhibited cytokinin-like activity as they promoted axillary shoots from node and adventitious shoot buds regeneration on the surface of all explants.