Callus Induction and Somatic Embryogenesis in Five Cacao (Theobronta cacao L.) Genotypes in Ghana

Different concentrations of Thidiazuron (TDZ) were evaluated for their effect on the induction of somatic embryos in five cacao genotypes. Immature flower buds were surface sterilized by immersion in 70% ethanol for 1 min, 30 sec, followed by 20 min in 2.5% sodium hypochlorite containing 0.1% tween...

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Bibliographic Details
Published in:Biotechnology (Faisalābād, Pakistan) Pakistan), 2010-09, Vol.9 (3), p.355-361
Main Author: Buah, J N
Format: Article
Language:English
Subjects:
2,4-D
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Summary:Different concentrations of Thidiazuron (TDZ) were evaluated for their effect on the induction of somatic embryos in five cacao genotypes. Immature flower buds were surface sterilized by immersion in 70% ethanol for 1 min, 30 sec, followed by 20 min in 2.5% sodium hypochlorite containing 0.1% tween 20. They were then rinsed five times in sterilized distilled water. Explants were prepared and placed on Primary Callus Growth (PCG) medium. Cultures were in darkness and at 25 degree C. Rapidly growing calli were induced by culturing staminode explants on a DKW salts-based Primary Callus Growth (PCG) medium supplemented with 20 g sucrose L super(-1), 9 mu M L super(-1) 2,4-D and thidiazuron at different concentrations. Calli were sub cultured unto a Secondary callus growth medium composed of low salts McCown's woody plant salts supplemented with 20 g sucrose L super(-1), 9 mu M 2,4-D L super(-1) and 1.4 mu M kinetin L super(-1). Somatic embryos were formed from embryogenic calli following their transfer to a hormone-free DKW salts-based embryo development medium. The rate of callus growth was significantly affected by Thidiazuron (TDZ) concentration in the PCG medium. This trend was also observed for the frequency of embryogenesis and number of somatic embryos produced from each responsive explant. TDZ concentration of 25.6 nM L super(-1) was found to be the optimal concentration for the induction of somatic embryogenesis in cacao. Somatic embryos formed from all the five cacao genotypes. Genotypes however, showed differences in their ability to produce somatic embryos, with Tei3 and IMC23 giving the highest frequency of somatic embryos (100 and 98%), respectively. In terms of number of somatic embryos, IMC23 and Atila7 were the best with 101 and 98 somatic embryos formed, respectively. Percentage responsive staminodes was high on medium with TDZ but this did not reflect in subsequent somatic embryogenesis compared to medium with high TDZ concentrations.
ISSN:1682-296X