2001 Volume 51 Issue 2 Pages 137-142
Tissue culture and histological studies were done to ascertain the effects of benzyladenine (BA)-preconditioning on direct shoot regeneration from cotyledonary node explants of mungbean. The highest direct shoot regeneration (93.3%), double-sided shoot initiation (65.0%) and average number of shoots per explant (2.7 shoots) were obtained when Pag-asa 7 explants are excised from seedlings germinated in basal medium (BM) consisting of MS salts and B5 vitamins with 1.0mgl-1 BA, and subsequently cultured in fresh medium of the same composition. Histological inspection of sections from germinating seeds in BM and BM+1.0mgl-1 BA sampled at 1 to 4 days from germination revealed bigger and developmentally more advanced axillary shoots in BA-preconditioned seedlings, a built-in advantage which could attest to the improved regenerability in BA-treated seedling explants over the control (BM only). During shoot initiation from explants, two treatments namely doubling of the concentration BA to 2.0mgl-1 and the addition of a non-ionic surfactant, Pluronic F-68 did not further increase the responses, but gave results comparable with those obtained using BM+1.0mgl-1 BA alone. Conversely, a BA-thidiazuron (TDZ) combination (each at 1.0mgl-1) when added to BM significantly reduced shoot induction to only 48.3% possibly due to increased callusing at the nodes in 55% of the explants. The importance and applicability of the regeneration system in tissue culture and/or genetic manipulations of mungbean and other Asiatic Vigna species is discussed.
