Effect of plant growth regulators on callus induction in dennettia tripetala bak. F. shoot explant

Abstract

Dennettia tripetala high consumption pattern and variety of uses, combined with its low germination and slow seedling growth, pose a serious threat to the extinction of this vital tree crop. Therefore, this experiment was undertaken to optimize a reproducible protocol for callus induction on shoot explants of Dennettia tripetala using different concentrations of plant growth regulators (PGRs). Shoot segments served as explants and cultured on Murashige and Skoog (MS) medium supplemented with different concentrations of Auxins, Indo-3-Acetic Acid (IAA) (0, 0.5, 1.0, 1.5. 2.0 and 2.5 mg/l) and cytokinins, Kinetin and 6-Benzyl amino purine (BAP) (0, 0.1 and 1.0 mg/l) alone and in combinations for callus induction. Among the MS media supplemented with either IAA/BAP or Kinetin, it was observed that the media supplemented with BAP did not produce callus. The callus induced in media supplemented with combinations of Plant Growth Regulators (PGRs) at varied concentrations varied in weight of callus, days of callus formation, colour and nature of callus. In combining PGRs in MS media, maximum callus of 0.63 g was produced in a media supplemented with IAA at 2.5 mg/l and kinetin at 0.1 mg/l 21 while media containing IAA at 2.5 mg/l with BAP at 1.0 mg/l generated maximum callus weight of 0.48 g. First day of callus formation for IAA with kinetin combinations and IAA with BAP combinations was 21 and 27 days respectively. MS media supplemented with 0.5 mg/l IAA+ 0.1 mg/l kinetin, 2.5 mg/l IAA+ 0.1 mg/l kinetin, 1.5 mg/l IAA + 1.0 mg/l kinetin and 1.5 mg/l IAA + 0.1 mg/l BAP gave early callogenesis at 21 and 27 days respectively. The result showed in this study indicated that high level of auxins (IAA) and moderate to high level of cytokinins was required for inducing optimum callus weight on cultured shoot of D. tripetala. Also, for inducing early callogenesis, IAA at 2.5 mg/l with kinetin at 0.5 mg/l is recommended.