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Nzaro G Makenzi, Wilton M Mbinda, Richard Oduor Okoth and Mathews Piero Ngugi
Sweetpotato (Ipomoea batata) is an important, nutritionally rich vegetable crop, but severely affected by environmental stresses, pests and diseases which cause massive yield and quality losses. Genetic manipulation is becoming an important method for sweetpotato improvement. In the present study, a reproducible and highly efficient protocol for in vitro plant regeneration of six Kenyan farmer preferred sweetpotato, Enaironi, KEMB 36, KSP36, Mugande, Kalamb nyerere, SPK 013 and SPK004 through direct shoot organogenesis from stem internodes explants was developed. The results revealed that Kalamb nyerere had the highest number of adventitious bud; for light (5.33 and 4.33) and dark (8.00 and 5.00) induction condition for all TDZ hormone level (0.25 mg/l and 0.15 mg/l). When explants incubated in 0.10 mg/l NAA the regeneration frequencies were the highest at 83.33% (Jewel) and 96.67% (Kalamb nyerere) for adventitious buds recovered from light and darkness respectively. This was the optimal auxin concentration which gave the maximum regeneration frequency with adventitious buds recovered from the dark. The best Kenyan sweetpotato genotypes for direct shoot organogenesis were Kalamb nyerere, Kemb 36 and SPK 004. The protocol presented in this work is suitable for improvement of sweetpotato genotypes through tissue culture methods and or genetic transformation.