2002 Volume 19 Issue 1 Pages 57-61
An efficient and simple in vitro regeneration protocol has been successfully developed from three inbred lines of Portulaca sp. cv. ‘Jewel’ that contain a lot of betalain. The present report describes the effect of thidiazuron [N-phenyl-N'(-1, 2, 3-thidiazol-5-yl) urea] (TDZ) on in vitro shoot regeneration from intact hypocotyl explant of seedlings. The optimum level of TDZ supplementation to the culture medium was 5μM for a 3 week-induction period followed by subculture of hypocotyl-derived callus on MS basal medium (MSO). Hypocotyls excised from 7 day-old seedling gave significantly higher number of regenerated shoots than those from 14 or 21 day-old seedling. The efficacy of thidiazuron was compared with N6-benzylaminopurine (BAP) and N6-furfurylaminopurine (KIN) (purine based cytokinins) on in vitro organogenesis. TDZ was found to be more effective than BAP and KIN as an inductive signal of regeneration. TDZ-supplemented medium with indole-3-acetic acid was not effective for the regenerative response. Transfer of the TDZ-stimulated shoots to growth regulator free MSO medium containing 3% sucrose resulted in the rapid and prolific growth of plantlets. In vitro shoots were rooted after culture on half-strength MS medium without growth regulator or in the presence of 2.5 or 5.0μM NAA and successfully acclimatized in greenhouse condition. The procedure developed in this study may be useful toward improvement and development of betalain through genetic manipulation.
