Aug 4, 2005

Research Projects

Send

Optimisation of the use of marker-gene-free transformation methods in potatoes; Part 2 (microinjection)

(2001 – 2004) BIOPLANT Biotechnologisches Forschungslabor GmbH, Ebstorf

Topic

The aim of the project is to test and refine microinjection as a new method for the direct transfer of genes. Plant tissues are to be tested to see whether they are suitable for microinjection. In addition, regeneration of the transformed cells is to be optimised.

In addition, genes of economic interest which control starch composition in potatoes are to be made available for microinjection.

Two different types of starch occur in the starch grains of potatoes: amylose (20-30%) and amylopectin (70-80%). There is an interest in producing genetically modified potatoes that produce only amylose-free starch. The genes for a certain enzyme (GBSS - granular binding starch synthase), which controls the formation of amylose starch, were therefore identified. The idea is to “switch off” this gene so that the metabolic route to amylose formation is broken.

Experiment description

• Firstly, plant lines are identified that are suitable for microinjection. The idea is to find optimum conditions for the formation of microcalli and for their regeneration.
• Following microinjection, the microcalli are regenerated into complete plants. The plants are planted out in the greenhouse and observed.
• Genes that modify starch composition in potatoes are isolated and cloned.

Results

Suitable plant material for microinjection was delivered to the University of Giessen.

A gene (GBSSI) was cloned that controls starch composition in potatoes. Expression cassettes (composite DNA sequences that are transferred to plant cells during transformation) were engineered to effectively silence the expression of the target gene GBSSI in transformed potato plants.