Author/Authors :
MARIGI, E. N. Kenyatta University - Department of Biochemistry and Biotechnology, Plant Transformation Laboratory, Kenya , MASANGA, J. O. Jomo Kenyatta University of Agriculture and Technology - Institute for Biotechnology Research, Kenya , MUNGA, T. L. Kenya Agricultural and Livestock Research Organization, Kenya , KARANJA, L. S. Kenya Agricultural and Livestock Research Organization, Kenya , NGUGI, M. P. Kenyatta University - Department of Biochemistry and Biotechnology, Plant Transformation Laboratory, Kenya , THAGANA, W. M. Kenyatta University - Department of Agricultural Science and Technology, Kenya , KIRUBI, D. Kenyatta University - Department of Agricultural Science and Technology, Kenya , MWANGI, M. Kenyatta University - Department of Agricultural Science and Technology, Kenya , GITHUNGURI, C. M. Kenyatta University - Department of Agricultural Science and Technology, Kenya , MUIRU, W. M. University of Nairobi - Department of Plant Science and Crop Protection, Kenya , MIANO, D. W. University of Nairobi - Department of Plant Science and Crop Protection, Kenya , ALAKONYA, A. E. Jomo Kenyatta University of Agriculture and Technology - Institute for Biotechnology Research, Kenya , ODUOR, R. O. Kenyatta University - Department of Biochemistry and Biotechnology, Plant Transformation Laboratory, Kenya
Abstract :
Cassava (Manihot esculenta Crantz) is a major food crop in developing countries, and holds potential for industrial use. It is, however, affected by various biotic and abiotic stresses that greatly affect its production. The existing regeneration and transformation protocols are not compatible with all cassava cultivars, thus efficient and robust transformation and regeneration protocols for farmer-preferred cultivars need to be optimised for ease of transfer of novel genes. The objective of this study was to develop an efficient transformation and regeneration protocol for a farmer-preferred Kenyan cassava cultivar. We cultured immature leaf lobe and stem explants on Murashige and Skoog (MS) medium, supplemented with varying concentrations of 2,4- dichlorophenoxyacetic acid (2,4-D), Picloram and á-naphthalene acetic acid (NAA). Plants were recovered on media with 6- Benzylaminopurine (BAP) and GA3 under a 16 hour light/8 hour darkness photoperiod regime. Results showed high regeneration and transformation frequencies for both cultivars. High frequencies of callus induction ( 98%) for both cultivars, were obtained when 2,4-D and Picloram were used. Similarly, both auxins initiated somatic embryogenesis, with Picloram producing the highest frequency of somatic embryos ( 92%) in TMS 60444, using stem explants. Gus assays revealed high frequencies of transformation of 77% (TMS 60444) and 60% (Kibanda meno mkubwa). This protocol offers promising perspectives for rapid improvement of these cultivars and, therefore, provides a platform for cleaning planting materials, as well as cassava genetic improvement programmes such as control of viral diseases.
