Callus Induction and Plant Regeneration from Dehusked Mature Seeds of Three Accessions of African Rice (Oryza glaberrima Steud.)

Three accessions of African rice (Oryza glaberrima Steud.), Guame, N/4 and SARI 1 were assessed for their callus induction and plant regeneration ability from mature dehusked seeds on Murashige and Skoog (MS), (1962) basal medium supplemented with varying concentrations of plant growth regulators. Mature dehusked seeds were inoculated onto callus induction medium consisting of MS supplemented with varying concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) in the range 0.0-6.0mg/l. All tested accessions exhibited highest callus induction at 4.0 mg/l 2,4-D. Callus induction frequency was significantly (p≤0.05) different among the accessions, as well as among the 2,4-D levels tested. Calli obtained were also sub-cultured on MS medium, further supplemented with varying concentrations (0.0-2.5 mg/l) of 6-benzylaminopurine (BAP). The highest regeneration frequency was obtained on medium containing 2.0 mg/1 BAP. However, callus induced on 3.0 mg/l 2,4-D and further sub-cultured on 2.0 mg/l BAP gave the best response in terms of shoot proliferation, shoot growth and root development; therefore, considered to be the optimum concentrations for callus induction and plant regeneration respectively. Plantlet regeneration was achieved only in the accession N/4 while Guame and SARI 1 exhibited poor regeneration response. Among the three African rice accessions evaluated, N/4 was the most promising in terms of callus induction frequency and regeneration ability. Keywords: Oryza glaberrima, callus induction, plantlet regeneration, shoot proliferation, 2, 4-dichlorophenoxyacetic acid, 6-benzylaminopurine