Abstract
Genetic transformation is considered as one of the most promising options for improvement of crop traits. Current transformation methods for sweetpotato depend on plant regeneration through organogenesis or somatic embryogenesis. Somatic embryogenesis and plant regeneration at a high frequency has been restricted to a few sweetpotato varieties. Three auxins namely: 2,4-dichlorophenoxyacetic acid (2,4-D), 4-fluoroamphetamine (4-FA) and 4,5-trichlorophenoxyacetic acid (2,4,5-T)were investigated in this study for enhancing somatic embryogenesis from various plant organs of recalcitrant African sweetpotato cultivars. 2,4-D was found to be the best (p ≤ 0.05) for induction of embryogenic callus. Cultivar Bwanjule had the highest (20.2%) embryogenic callus frequency among the five African cultivars tested. The highest number of plants in this study was regenerated from the non-African cultivar variety Jonathan on media supplemented with 0.2 mg Zeatin. The emergence of roots from callus of recalcitrant Ugandan cultivars and the comparable high embryogenic responses in this work demonstrate the potential for regenerating plants from African cultivars that have not been regenerated before. The regeneration of roots in this work could be useful for the initiation of root cultures. The most important application of this work is in genetic transformation of sweet potato, particularly for improvement of resistance to weevils. Key words: Embryogenesis, plant growth regulators, plant regeneration, Ipomoea batatas
Highlights
Sweetpotato (Ipomoea batatas Lam.) is a member of the family Convolvulaceae, genus Ipomoea, and section batatas
Cultivar Bwanjule had the highest frequency (51.3%) of callus while Semanda had the lowest (40.3%) frequency (Figure 2). Both the Plant growth regulator (PGR) and plant organ were found to have a significant effect on total callus induced when investigated within cultivars
The present study was initiated with the aim of developing a protocol for induction of embryogenic callus from recalcitrant African cultivars
Summary
Sweetpotato (Ipomoea batatas Lam.) is a member of the family Convolvulaceae, genus Ipomoea, and section batatas. It is the only hexaploid (6x = 90) species in the batatas section. Sweetpotato is cultivated in tropical and sub-tropical areas of the world because of its edible. Tuberous roots, which are high in starch and vitamin A (Woolfe, 1991). Young leaves and vine tips are eaten and they are an excellent source of vitamins A, C, and B2 (Hill et al, 1992). China produces more than 80% of the world’s sweetpotato followed by Nigeria and Uganda. Sweetpotato has high economic value in developing countries, its productivity is constrained by various biotic and abiotic factors
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