Development of transgenic sweet potato varieties (ipomoea hatatas l. lam) expressing bt proteins active against sweet potato weevils
Sweet potato is grown in Sub-Saharan Africa (SSA) as a staple food for the urban and rural poor. This notwithstanding, relatively high production losses are incurred due to viral diseases, responsible for up to 50% and weevils (Cylas spp.) constituting between 60-100%. Conventional methods have previously been applied to solve the weevil problem but with little or no success. Instead, host plant resistance is the ideal strategy to control weevils through genetic engineering since there is no resistance in the crop's natural gene pool. The main objective of this study is therefore to develop genetically modified sweet potato with resistance against coleopteran pests by expression of multiple Bacillus thuringiensis (Bt) toxins (Cry7 Aa1 and ET33-34). The toxins were selected for plant expression because of their high toxicity against C. puncticollis and C. brunneus and they had low sequence identity, important for the potential of cross-resistance. Regeneration and transformation by organogenesis of sweetpotatoes will be conducted using a two-step protocol including 2,4-D for step 1 followed by thidiazuron, zeatin or kinetin for step 2. Statistical analysis will be carried out using Genstat statistical package version 10 by logistic regression. This study seeks to develop weevil resistant sweet potatoes to reduce and deal with production losses caused weevil infestation on storage roots therefore addressing food security for the rural poor.