Can wheat be genetically engineered to become durably resistant to mildew?Individual resistance genes to mildew protect wheat plants against some, but not all, variants of this pathogen. A series of field trials will be carried out to test various means of genetically engineering wheat to enhance its resistance. The combination of several genes will play a central role in this project.BackgroundWheat has various genes that are responsible for resistance to mildew. One of these genes has seven variants, known as alleles. Individually, these alleles make wheat resistant to some, but not all, variants of the mildew fungus. There are in fact varieties of conventional wheat that have a certain degree of resistance to mildew. However, this resistance is often lost within a short time-frame. To overcome this shortcoming, genetic engineering will be used to combine the alleles. Field trials are the only way to find out whether long-term resistance can be achieved by this means.ObjectivesVarious transgenic wheat lines will undergo comprehensive testing in a field trial (cf. Keller project I). The aim is first to establish whether the individual lines do indeed have better resistance to mildew. The second aim is to investigate how the additional gene affects the performance of the plant - in terms of yield, for example. The project also aims to analyse the effect of the environment on the plants’ resistance properties.MethodsTransgenic wheat lines - each containing one of the seven resistance alleles - will be developed and tested over three years for properties including seed maturation, yield and resistance following artificial and natural infection with mildew. Some of these lines will also be cultivated as a seed mixture. At the same time, wheat lines will be produced which combine the different alleles in the same plant. Both trials will test whether and to what extent mildew develops less frequently.SignificanceThis is the first time that a field trial of this size will be carried out with transgenic plants in Switzerland. The project will not only elicit a major response from the general public, it will also provide new facts about the possible benefits of genetically modified plants.