Genetic Engineering Of Sweetpotatoes (Ipomoea Batata (L.) Lam) Using Isopentenyltransferase Gene For Enhanced Drought Tolerance

Drought adversely affects crop production worldwide leading to approximately 70% of yield reduction. Significant yield loss is common among the major cereals such as maize, wheat and barley due to frequent and severe drought as a result of climate change. Therefore, there is a great need for drought tolerant or escaping crops that still yield amidst erratic climatic manifestation. Sweetpotato is capable of producing high yield in a short period of time making it suitable for cultivation in regions with limited or erratic rain water supply where other food crops grow with difficulty. However, it is sensitive to water deficit which adversely affects crop growth and yield. Sweetpotato improvement by conventional hybridization is limited because of its high male sterility, sexual incompatibility and hexaploid nature of its genome. This study therefore aimed at developing sweetpotato varieties with improved tolerance to water-deficit stress for sustainable production under water-limited conditions. Three sweetpotato genotypes: Jewel, Kemb36 and Ksp36 were transformed using isopentenyltransferase gene (IPT) that delays drought-induced senescence via up-regulation of cytokinin biosynthesis, under the control of a water-deficit responsive and maturation specific promoter (PSARK). To evaluate their transformability and regenerability, the PNOV-IPT gene construct was introduced into sweetpotato via Agrobacterium tumefaciens strain EHA101 and the plants subsequently regenerated via somatic embryogenesis. Jewel genotype recorded the highest transformation and regeneration frequency followed by