Quick Dips

Transforming Grasses

Grasses are considered to be very difficult to manipulate genetically, but a research group at Massey University has been able to develop a successful new method for introducing foreign genes into grasses.

Professor Barry Scott's team have used a filamentous fungus, Acremonium lolii, to ferry new genes into perennial ryegrass. The fungus is a natural symbiont of the grass and acts as a host for the genes. Two genes have been transferred using this technique. One provides resistance to the antibiotic hygromycin; the other, GUS, acts as an "reporter" of the gene's location and activity. It does this by producing an enzyme that converts a colourless chemical substrate into an insoluble blue product, showing up clearly.

The fungus cells carrying the genes are physically inserted into grass seedlings. As the seedlings grow and develop, the fungus spreads through the intercellular spaces of the leaves, establishing symbiosis with the grass. Acremonium lolii has lost the ability to spread from one grass to another, and so is maintained in the grass population by maternal inheritance through the seed. Scott and his colleagues have tracked the marker genes into the next generation of plants.

Plant pathologists are interested in using the GUS reporter gene system to monitor how fungal pathogens infect and invade plants. The research is part of a larger programme aimed at developing genetic techniques to study and manipulate genes involved in the synthesis of a range of novel compounds produced by the fungus.