African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12217

Full Length Research Paper

Explant type and hormone regime influences somatic embryogenesis and regeneration of cassava

Easter D. SYOMBUA
  • Easter D. SYOMBUA
  • Plant Transformation Laboratory, Department of Biochemistry and Biotechnology, Kenyatta University, P. O. Box 43844-00100, Nairobi, Kenya.
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Christine N. WANYONYI
  • Christine N. WANYONYI
  • Plant Transformation Laboratory, Department of Biochemistry and Biotechnology, Kenyatta University, P. O. Box 43844-00100, Nairobi, Kenya.
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Mark O. ADERO
  • Mark O. ADERO
  • Plant Transformation Laboratory, Department of Biochemistry and Biotechnology, Kenyatta University, P. O. Box 43844-00100, Nairobi, Kenya.
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Wilton M. MBINDA
  • Wilton M. MBINDA
  • Department of Biochemistry and Biotechnology, School of Pure and Applied Science, Pwani University, P. O. Box 195-80108, Kilifi, Kenya.
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Mathew P. NGUGI
  • Mathew P. NGUGI
  • Plant Transformation Laboratory, Department of Biochemistry and Biotechnology, Kenyatta University, P. O. Box 43844-00100, Nairobi, Kenya.
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Amos E. ALAKONYA
  • Amos E. ALAKONYA
  • Institute for Biotechnology Research, Jomo Kenyatta University of Agriculture and Technology, P. O. Box 62000-00200, Nairobi, Kenya.
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Richard O. ODUOR
  • Richard O. ODUOR
  • Plant Transformation Laboratory, Department of Biochemistry and Biotechnology, Kenyatta University, P. O. Box 43844-00100, Nairobi, Kenya.
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  •  Received: 09 May 2019
  •  Accepted: 12 June 2019
  •  Published: 19 June 2019

Abstract

Cassava (Manihot esculenta Crantz) is a tropical root crop that serves as a food staple and a vital income source to resource deprived farmers in the tropics. Despite its importance, cassava production and consumption is faced by a myriad of biotic/abiotic constraints. Genetic transformation which can be applied to mitigate these challenges however has as a prerequisite the availability of robust regeneration systems. This study evaluated the effect of explant type and hormone regime on somatic embryogenesis and regeneration of Kenyan cassava cultivars. The embryogenic competence of immature leaf lobe and stem explants of three cassava cultivars was determined by culturing them in MS medium supplemented with picloram (4, 6, 8 and 10 mg/l).  The optimum media composition for embryo maturation, germination and plant recovery was assessed by culturing embryos in media supplemented with varying concentrations of 6-Benzylaminopurine (BAP), α–Naphthalene acetic acid (NAA) and Gibberellic acid (GA3). Somatic embryo formation frequencies in leaf explants were significantly higher (P≤0.05) than in stem explants. Embryo formation rates were found to increase with increasing concentrations of picloram. Cultivar 08/080 gave the least response to embryogenesis while embryogenesis rates for cultivar 08/274 were similar to the control cultivar TMS 60444. Maturation and plant recovery rates differed significantly with regard to the ratios of BAP, NAA and GA3 in the maturation media. The optimal medium for embryo germination and plant recovery was supplemented with 1 mg/l BAP, 0.02 mg/l NAA and 1.5 mg/l GA3. This optimized regeneration protocol can be coupled with mutation breeding or genetic transformation to improve the cassava germplasm.

 

Key words: Cassava, explant, regeneration, somatic embryogenesis, plant growth regulator.