Effect of 2,4-D, explants type and cultivar on the callogenesis expression of cassava (Manihot esculenta Crantz) in Ghana

Abstract

Modern biotechnological applications in breeding programmes for economically-important crops like cassava begins with successful establishment of stable and active callus cultures for somatic embryos which can be genetically manipulated and induced into planting materials. We have investigated the effects of explants (leaves, stem petiole and axillary buds), auxin (2, 4-D) concentrations (8, 12 and 15 mg/l) and cultivar in the induction of callus cultures from local cassava varieties in Ghana - Tuaka, Afisiafi, Afebankye and Doku. Callus formation was successfully induced in all explants (leaf, petiole and auxiliary buds) from the four cassava cultivars. Generally, there were no significant differences in callogenesis of the different explants at the three different 2,4-D concentrations (p < 0.05) producing 75% callus for explants. The stem petiole or stem bark produced the least percentage of callus per cultivar at all the auxin concentrations. However, the leaf explants were superior in callus formation in all the cassava varieties. Although, statistically insignificant, the 8 mg/l 2,4-D concentration was visually the best in callus formation from explants both within and across the cassava cultivars. This study had shown that different cassava explants respond differently to tissue culture conditions established for callus culture formation.

Key words: Auxin, callogenesis, callus induction media, cassava Manihot esculenta Crantz, 2,4- dichlorophenoxyacetic acid (2,4-D), somatic embryogenesis.