Gene expression of beta carotene genes in transgenic biofortified cassava

Cassava is an important food for millions of people around the world. However, cassava is deficient in protein, iron, zinc, pro-vitamin A and vitamin E. Cassava biofortified with pro-vitamin A can help reduce Vitamin A Deficiency among the undernourished communities that rely upon it for sustenance. BioCassava Plus project has developed transgenic cassava that expresses beta carotene in roots using root specific patatin promoter. This study aimed at confirming expression of nptII, crtB and DXS genes. Leaf and roots samples were obtained from confined field trial at KARI Alupe at 12 months after planting. RNA was isolated from cassava roots and leaves using a modified Dellaporta protocol, analyzed for expression of DXS, crtB and the selectable marker, nptII using the one step RT-PCR kit (Qiagen) and analyzed through gel electrophoresis. DXS, crtB and nptII genes were expressed in the roots as anticipated. On the contrary, DXS and crtB genes were also expressed in the leaves of the transgenic cassava despite the use of root specific patatin promoter. This finding indicates that the promoter confers expression in leaves too. Intensive molecular screening of the biofortified transgenic cassava is important for risk assessment that informs on integrity of the promoter gene and confirms expression of the beta carotene genes.