African Journal of Biotechnology Vol. 5 (16), pp. 1435-1440, 17 August 2006   

ISSN 1684–5315 © 2006 Academic Journals        

Full Length Research Paper

Genotypic variability in callus induction and plant regeneration through somatic embryogenesis of five deepwater rice (Oryza sativa L.) cultivars of Bangladesh

L. Khaleda and M. Al-Forkan*

Department of Genetic Engineering, University of Chittagong, Chittagong-4331, Bangladesh.

*Corresponding authors E-mail: alforkancu@hotmail.com. Tel: 88031-726311-4, Ext. 4414. Fax: 88031-726310.

Abbreviations: 2,4-D=2,4-dichlorophenoxy acetic acid; CH = Casein hydrolysate; NAA=1-napthalene acetic acid; BAP=6-benzyl amino purine; MSS=Mature Seed Scutellum; Kn=Kinetin

Accepted 23 June, 2006

Experiments were carried out to induce embryogenic callus and plant regeneration from five different deepwater rice cultivars. Using mature embryos as explant, all the cultivars demonstrated high callus induction and plant regeneration frequencies. When coleoptile and root segments used as explants, they had low frequencies of embryogenesis. Depending on different genotypes, the best plant regeneration was obtained on LS (Linsmaier and Skoog, 1965) based medium supplemented with 2 mg l^-1 BAP + 1.5 mg l^-1 2,4-D. Large variabilities in callus growth and plant regeneration potential were revealed among the cultivars tested. Cultivar HA-8 formed a high frequency (78%) of callus than that of other cultivars. In contrast cv. HA-1 produced the highest percentage (72%) of plant regeneration. The callus growth potential was not correlated with the plant regeneration potential. Coleoptiles and root segments produced calli, which did not develop any shoot bud in regeneration media. Moreover, the calli turned blackish, watery and translucent after 25-28 days of culture. It is clear that mature seed scutellum (MSS) is the best explant for callus induction and plant regeneration.

Key words: Callus, regeneration, embryogenesis, genotypic variability, deepwater rice.