Determination of the regeneration potential of selected farmer- prefered sweet potato genotypes in Kenya via somatic embrogenesis
Sweet potato is one of the world's highest yielding crops in terms of production per unit area, exceeding that of major cereals. It is the seventh most important food crop and ranks third after potato and cassava in the world production of root and tuber crops. Sweet potato is an important crop in developing countries, which accounts for 95% of the total world production. In Kenya, sweet potato is an important food security crop grown mainly by women for household consumption and as a source of family cash income. Although sweet potato is considered to be a food security crop, its production is constrained by virus disease, insect pests among others. Controlling this has not been promising. Biotechnological interventions such as tissue culture and genetic engineering can offer alternative strategies to alleviate these constraints. Development of a reliable in vitro plant regeneration procedure for sweet potato is a pre-requisite for its improvement by genetic transformation. The objective of this study was to determine the regeneration potential of selected farmer-preferred sweet potato genotypes via somatic embryogenesis. In this study, 10 popular sweet potato genotypes (Enaironi, Kemb 10, Kemb 23, Kemb 36, KSP 36, Mugande, SPK 004, SPK 013, Ex-shimba hills, and Zapallo) of different origin were tested for their potential to produce plantlets via somatic embryogenesis. Leaf and stem explants of each variety were cultured in the dark in a solid MS based medium supplemented with 2,4-D at 0, 0.5, 1.0, 2.0, and 5.0 mg/L to determine optimal levels to initiate callus induction. Callus induction and embryogenic calli were obtained from both explants in all the sweet potato genotypes at optimal 2,4-D concentrations of 0.5 mg/L and 2.0 mg/L. Of the 10 genotypes tested, plantlet regeneration and tuber formation was achieved in 7 and 4 genotypes. Results from these studies show that the genotype and 2,4-D concentration, influenced the ability of plantlet regeneration. Both leaf and stem explants were found to be effective in their potential to regenerate plantlets. These results will avail efficient regeneration protocols across different sweet potato genotypes in order to facilitate genetic transformation work of sweet potatoes in other laboratories in the region.