Mar 4, 2009

Research Projects

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Survival ability of cyanophycin-producing potatoes

(2008 – 2011) University of Rostock, Institute for Land Use (ILN)

Topic

The aim of this project is to investigate whether genetically modified potato tubers that produce cyanophycin overwinter better than conventional tubers and might therefore emerge in later crops. Cyanophycin is a biopolymer that is used for various industrial applications.

Since accumulation of the cyanophycin protein interferes severely with the carbohydrate metabolism of the potatoes – the storing of proteins comes at the expense of carbohydrate storage – the tubers of the genetically modified potato plants might contain more short-chain sugars than the wild type. This might lower the freezing point and therefore increase the frost resistance of the genetically modified potatoes. Self-sown potatoes might then survive the winter better and continue to reproduce the following year.

If the frost resistance of the genetically modified potatoes is the same, tests need to be carried out to determine whether the rotting process of self-sown potatoes takes place without harming the arable soil, since cyanophycin is not a substance that occurs naturally in the soil.

This project will examine the following questions:

• Which of the available transformed potato plants that produce cyanophycin are best suited for release?
• Does the modification of the plant substances in the transgenic potatoes lead to better frost resistance?
• Does the change in the plant substances of the transgenic potatoes lead to changes in the rotting processes that might harm the arable soil (e.g. through a change in the pH level)?

Experiment description

Identification and characterisation of suitable potato plants

The release experiment requires potato plants that have as few copies as possible of the foreign gene at a single integration site. The available plants will be examined using the Southern Blot method and two of them will be selected.

The selected plants will be grown in the greenhouse over two generations to compare their characteristics with those of the isogenic variety and to check their trait stability. The growth habit of the potato plants and the phenotype, size and weight of the tubers will be recorded and the cyanophycin and starch content of the tubers will be measured.

In addition, the PCR method will be used to analyse the level of RNA for the new gene – the cyanophycin synthetase gene. The level of RNA provides an indication of gene activity.

Genetically modified potatoes on the trial field

In each year of the trial, potatoes will be buried after harvest at two different sites at two different depths (10 cm and 30 cm). During the 6-7-month overwintering period, ten tubers will be dug up from each site at eight different times and examined in the laboratory. Among other things, the tests will measure the water, carbohydrate, protein and cyanophycin content, as well as the freezing point and the pH level of the intercellular fluid.