CBN-V Video Archives - S7-35
Transfer and Expression of an Artificial Storage Protein (ASP1) Gene in Cassava (Manihot esculenta Crantz): Towards Improving Nutritive Value of Storage Roots

Zhang P.¹, J.M. Jaynes², I. Potrykus¹, W. Gruissem¹ and J. Puonti-Kaerlas¹

1. Institute for Plant Sciences, ETH-Zentrum/LFW E 17, CH-8092 Zürich, Switzerland zhang.peng@ipw.biol.ethz.ch
2. Demgen Inc. 1051 Brinton Rd, Pittsburgh, PA 15221 USA

        The storage roots of cassava contain starch up to 85% of their dry weight, but are deficient in protein. In order to increase the protein content of cassava storage roots, a 284 bp synthetic gene asp1 coding for a storage protein rich in essential amino acids (80%) was introduced into embryogenic suspensions of cassava by Agrobacterium tumefaciens-mediated gene transfer. Hygromycin-resistant friable embryogenic callus lines were either used directly for embryo formation and plant regeneration or to establish transgenic suspension lines. Molecular analysis showed the stable integration of asp1 in cassava genome and its expression at RNA level in transformed suspension lines. PCR and Southern analysis proved the stable integration of the transgene in 7 regenerated plant lines, the number of integration sites of asp1 varying from 1 to 6. The expression of asp1 at RNA level was demonstrated by RT-PCR amplification of the asp1. The ASP1 tetramer could be detected in leaves as well as in primary roots of cultured transgenic plants by Western blots. These results indicate that the nutritional improvement of cassava storage roots may be achieved by constitutive expression of asp1 in transgenic plants.

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