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.

The Influence of Plant Growth Regulators and Light Supply on Bitter Cassava Callus Initiation for Starch Production

“…Next, the explants were soaked in 70% ethanol for 5 min, then bleached with 5.75% sodium hypochlorite with 2-3 drops of TWEEN® 20 for 10 min. After each soaking, the explants were rinsed at least three times with sterile distilled water [9,12]. The sterile explants were cut into small pieces of 5 mm which were inoculated in a media plate (4 explants per plate).…”

“…The exposition period of the explant to ethanol is different for each plant and from different parts of the same plant [17]. As an example, leaf cells have less lignified thin cell walls except the leaf epidermis [12]. The thinness of the leaf cell wall might be one of the reasons why the leaf explant could not withstand our sterilization technique.…”

“…The contradiction of the results obtained could also be due to the cultivar type and explant used. Fletcher et al [12] proposed that different explants and cultivars react differently to different concentrations of PGR. In their study using different cassava cultivars available in Ghana, among the 3 concentrations of 2,4-D used i.e., 8, 12, and 15 mg/L, 2,4-D at 8 mg/L achieved a better callus growth of Afisiafi cultivar for both leaf (75%) and bark (25%).…”

“…In the case of callus growth, the major PGRs that influence its development are auxin and cytokinin. 2,4-dichlorophenoxyacetic acid (2,4-D) has been reported as the most effective auxin for cassava callus formation [8,12]. For cytokinin, thidiazuron (TDZ) induced a higher percentage of callus formation followed by 6-Benzylaminopurine (BAP) and kinetin.…”

“…Moreover, light supply, as another culture parameter, was also investigated. Cassava callus culture can grow in both dark and light conditions, at a temperature of 25-28 °C within 1 month [8][9]12]. Light supply influenced the initiation time of the culture i.e.…”