Transgenic aspens: Testing the reliability of male sterility systems

Approximately two hundred transgenic aspens from a precursor project which have been cultivated in the greenhouse will be investigated. They are equipped with seven different gene constructs which use four different cytotoxin genes and four different promoters. Since poplars normally flower only after eight years, some of these strains also contain an ‘early-flowering’ gene.

Molecular-biological investigations

First the sites in the plant genome where a gene construct has been inserted will be investigated using PCR and Southern Blot .

Tests will also be carried out to determine whether the newly inserted cytotoxin genes are expressed only in the anthers, as intended, or in other tissues as well. This will involve a special type of PCR that measures the number of copies of specific RNA sequences, a procedure which enables conclusions to be drawn about whether and how strongly a gene is expressed.

Microscopic examinations and germination tests

Flower formation in the transgenic poplars will be studied throughout the year. Each flower will be bagged before pollen formation to prevent the spread of any fertile pollen. The presence of pollen will be investigated and quantified by dying the flowers and examining them under a microscope.

The germination capacity of the harvested pollen will be tested either by direct crossing with female stigma or by applying the pollen to agar-coated slides. Any seedlings obtained as a result of the crossing will then undergo molecular analysis.