Abstract

Our project aims to improve the starch composition in sweet potatoes through genetic editing, increasing the proportion of amylose to provide a wider variety of food options for those with blood sugar management needs. In pursuit of our project goals, we designed and constructed several components. Among these, we thoroughly characterized the composite part BBa_K5399007. We constructed BBa_K5399007 based on BBa_K5399008 and successfully obtained the SBEI and SBEII gene knockout strain (named Cas-SBE) of sweet potato (Ipomoea batatas). The SBE genes encode starch branching enzymes. The Cas-SBE strain exhibited normal growth, with stem diameters nearly doubling and internode lengths reduced to 25% of the wild type (WT), resulting in a shorter and sturdier overall phenotype. Testing revealed that knocking out the SBE genes significantly boosted amylose content, with the best strain achieving a 104% increase. Additionally, the analysis of resistant starch content showed that the Cas-SBE plants had an increase of 121%-133%. Foods with high resistant starch content can provide anti-glycemic effects.