Efficient Plant Regeneration of Selected Kenyan Sweetpotato (Ipomoea batatas (L.) Lam.) Cultivars through Somatic Embryogenesis

Abstract

Sweetpotato is an important food crop in the world as well as in Kenya. Various fungal and viral diseases are major constraints in its production and are currently threatening the sweetpotato production in sub-Saharan Africa. Genetic engineering offers significant potential for the crop’s genetic improvement. However, this is limited by the low efficiency and strong genotype dependency in tissue culture. This study aimed to establish an efficient somatic embryogenesis and plant regeneration system using shoot apical meristem explants of sweetpotato. Three sweetpotato cultivars that are widely grown in Kenya; KSP36, Kemb36 and Mweu mutheke along with an exotic model cultivar Jewel were evaluated. The maximum somatic embryogenic induction, at 96.72%, was obtained from explants cultured on Linsmaier and Skoog salts and vitamins medium supplemented with 0.5 mg/l dichlorophenoxyacetic acid and 0.2 mg/l zeatin riboside. The highest number of shoot induction (33) was observed after transfer of embryonic callus to embryo maturation medium supplemented with 2 mg/l abscisic acid. Significant differences were observed between cultivars for somatic embryogenesis and plant regeneration. Jewel showed the best response, while Mweu mutheke was the least responsive under the culture conditions tested in this study. Regenerated plants were successfully rooted and grown to maturity after hardening in soil in the greenhouse. Such a robust, successful and efficient system possesses the potential to become an important tool for crop improvement and functional studies of genes in sweetpotato