Effect of bavistin on in vitro plant conversion from encapsulated uninodal microcuttings of micropropagated Bacopa monnieri (L.)--an Ayurvedic herb.

A reliable and reproducible protocol for contamination free plant recovery system from alginated encapsulated uninodal microcuttings of micropropagated Bacopa monnieri L. have been developed after storage at 18 degrees C for 45 days. Node segments excised from freshly micropropagated plants were encapsulated as single explant beads with 3.0% sodium alginate and 80 mM CaCl2 2 H2O. To find out the optimal concentration of fungicide bavistin for efficient plant recovery different concentrations of bavistin (1.0 - 15 mg l(-1)) were incorporated in to the encapsulation medium. 3.0mg l(-1) bavistin showed no reduction in plant conversion and generated maximum number of shoots (45.6 +/- 1.69) at high frequency with out any contamination after storage up to 45 days at 18 degrees C. At high concentrations (13 and 15 mg l(-1)), rupturing of calcium alginate coats after 8 - 9 days and gradual decline in the number of shoots indicates the toxic effect of bavistin on plant conversion. Encapsulated node cuttings stored up to 45 days regenerated shoots (5.2) and multiple shoots (45.6) in MS basal and hormone medium respectively. Maximum shoot length (8.2 +/- 0.37 cm) was observed from encapsulsted node cuttings incorporated with 3.0 mg l(-1) bavistin on MS basal medium. 90% of the recovered plantlets were hardened off and successfully established in soil.