Fungi are responsible for causing many plant diseases. Genetic engineering is being used to create fungus resistant crops.

For some plant species (potatoes, maize, cereals, grapes) fungal infestations - e.g. blight, grey mould, or  Phytophthora - can lead to significant yield losses.

Fungal diseases are usually combatted with chemical fungicides or heavy metal compounds (e.g. copper vitriol). For some crops, fungus resistant cultivars have been developed using conventional breeding methods.

Intensive work is underway to develop transgenic plants with acquired fungal resistance. So far, none of these efforts have resulted in commercially viable varieties.

Several approaches are under investigation:

• Transfering bacterial genes encoding anti-fungal enzymes, e.g. chitinase or glucanase.
• Transferring genes for anti-fungal substances already produced by some plants.
• Augmenting the hypersensitive reaction: Many plants cause individual, infected plant cells to die at the site of fungal infection, effectively stopping the infection in its tracks. This mechanism can be recruitred or enhanced by genetic engineering.