Abstract

S3-07

Transformation of African Cassava for Increased Starch Production.

Ihemere U.E.¹, D.I. Arias-Garzon² and R.T. Sayre^{1, 2}

1. Departments of Horticulture and Crop Science

Cassava is a good candidate for starch production studies because it has a high photosynthetic rate, an ability to grow on poor soils and it is protected from many pests and herbivores due to the presence of cyanogens.  The objective of this study is to increase the root starch production potential of cassava by introducing into the plant a modified E. coli glgC gene, which is driven by the tuber-specific patatin promoter and is also expressed in cassava roots.  The choice of the E. coli glgC gene, which encodes ADP-glucose pyrophosphorylase (AGPase), over the plant’s genes was because the glgC gene encodes a homodimeric AGPase while the plant’s AGPase is a heterotetrameric enzyme, that makes cloning difficult.  In addition, the modified E.coli gene encodes an enzyme with higher activity than the plant enzymes.  Twenty three putative transformed plants were obtained of which seven have been proven to carry the transgene by PCR and RT-PCR analysis.  Enzyme assays and Southern blotting are being carried out to confirm the transformation of the plants.  It is proposed that enhanced conversion of sugars to substrates for starch synthesis in roots will generate plants with higher starch yields and faster root maturation.