CBN-V Video Archives - S7-13
Regeneration and Transformation of African Cassava (Manihot esculenta Crantz) Germplasm

Hankoua, B.B. ¹, S.Y.G. Ng ¹, J. Puonti-Kaerlas², I. Fawole¹, A.G.D. Dixon¹ and M. Pillai¹

1. International Institute of Tropical Agriculture, (IITA), Oyo Road, Ibadan, Nigeria B.HANKOUA@CGIAR.ORG
2. European Patent Office, D-80298 Munich, C102, Germany

        Twenty cassava genotypes selected from a range of African landraces and improved germplasm were assessed for their ability to undergo somatic embryogenesis and organogenesis. Embryo induction medium supplemented with picloram (12 mg/l) gave a higher frequency of embryo induction than when supplemented with 2,4-D (4 mg/l). No significant difference in somatic embryogenesis between apical meristems and immature leaf lobes was observed. Secondary and cyclic embryogenesis was established in 13 cassava genotypes. Shoot organogenesis was achieved from cotyledon pieces of maturing somatic embryos of 12 cassava genotypes at a frequency of 5% to 78% depending on the genotype. An average of 0.1 to 12 plantelets was recovered from each responding explant. Regenerated plantlets were successfully established in the field. Preliminary analysis of the ploidy level of the regenerants by flow cytometric and chromosome count found no abnormalities. The frequency of organogenesis and the number of plantlets regenerated were further improved by adding silver nitrate and a higher concentration of agar in the medium. Compatibility screening was conducted of four Agrobacterium strains with four cassava genotypes; the best combinations were identified based on transient GUS assays. Transformation studies are underway at IITA using the two best combinations.

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