Assessing the Regenerability of Selected Kenyan Cassava Genotypes via Somatic Embryogenesis

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Date
2017
Authors
Wanyonyi, Christine Nakhumicha
yombua, Easter David S
Ngugi, Piero Matthew
Thagana, Wilson
Okoth, Richard Odour
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Abstract
: Cassava is a valuable source of calories in countries where malnutrition is widely spread. Despite its many uses as food, feed and in industries, it’s constrained by biotic and abiotic stresses. Attempts to overcome challenges in cassava production by conventional breeding are limited. The application of genetic transformation to introduce agronomically useful traits would greatly compliment classical breeding approaches. The objective of this study was to determine the regenerability of selected Kenya cassava genotypes for use in genetic transformation studies. Three genotypes (Ex-ndolo, Karibuni and Shibe) were collected from coastal and eastern agro ecological zone based on their traits which were high yielding, early maturity and mealiness and maintained at the Kenyatta University Plant Transformation Laboratory glasshouse. Stokes were established in vitro and maintained on media containing Murashige and Skoog salts with vitamins, 30g/l sucrose and 3.0g/l gelrite and used as source of sterile explants. Picloram and 2, 4-dichlorophenoxyacetic acid were used to induce somatic embryos using leaf and stem explants under light and dark photo regimes. The differences in frequencies of somatic embryogenesis ranged between 31.95-81.48% for leaf explants and 19.65- 42.83% for stem explants for all four concentrations under study while varying the photoperiod. Embryogenic calli was matured on media supplemented with different concentrations of 6-Benzylaminopurine, αnaphthaleneacetic acid and gibberellic acid before being transferred to regeneration media. Shoot development from somatic embryos had significant differences between genotypes. Ex-Ndolo was highly responsive to the maturation media and formed shoots when the embryos originated from leaf explants for both 2, 4- dichlorophenoxyacetic acid and picloram were matured. Root induction from shoots was relatively low, ranging between 10±2.82-26±1.41. Overall picloram emerged as the best auxin for somatic embryo induction while leaf explant was superior to stem in terms of embryogenic ability.
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Keywords
explant, auxin, photo regimes, somatic embryo
Citation
Wanyonyi, C. N., Syombua, E. D., Ngugi, P. M., Thagana, W., & Okoth, R. O. Accessing the regenerability of selected Kenyan cassava genotypes via somatic embryogenesis.