'Why is it so' drives search for gene defences

Photo of Dr Peter East

[Photo by Brad Collis: Dr Peter East: a fascnination with genetics led him to current research]

Helen Olsen reports on GRDC-supported research to discover "bargaining chip" technology aimed at ensuring the Australian grains industry has access to the latest advances in crop science

A desire to "find out what makes things tick", combined with the latest in gene technology, has led CSIRO entomologist Dr Peter East and his team to discover a previously unknown - and potentially valuable - diversity in insect-plant interactions.

Dr East leads the joint GRDC-CSIRO Grain Protection Genes (GPG) program, which is looking to develop and patent Australian biotechnology to use as a bargaining chip with multinational companies who have other technologies that Australian agriculture needs.

Dr East says that genetics, and the profound effects that genes have on organisms, inspired him to find answers to questions such as why some insect species are successful crop pests, and how plants can defend themselves against them. "I"ve always had an analytical mind, which led me into science, and my fascination with genetics has led me to the research that I am doing now," he explains.

Genetics, specifically plant and insect genetics, is at the heart of the research in the GPG program. The genetic defences of plants against insect pests, and the genes that allow insects to overcome these defences and extract maximum nutrition from crop plants, are the program"s two central themes.

Tools that can "read" the genome (complete genetic makeup) of insects, and DNA micro-arrays, which show what genes are making proteins under different conditions, enable Dr East and his colleagues to explore insect-plant interactions at a more fundamental level than was previously possible. "These tools allow us to explore questions at a much higher level of complexity, and to find answers to such questions as why certain insect species become crop pests while other closely related insects don"t become pests."

An example is the research into the success of pest species of Helicoverpa caterpillars (budworms) on host cereal and legume crops. The research group has identified 3500 different genes that are expressed in the gut of the pest budworms.

"This large collection of genes has revealed a surprising diversity in the types of digestive enzymes in the gut," Dr East says. This diversity might be part of the reason why these insects feed so effectively on a wide variety of crop plants, as well as emabing them to overcome the natural plant defences. Dr East says that with the increased understanding of what"s inside the Helicoverpa gut, there is now a real possibility of finding "a chink in the armour".

Other research in the GPG program includes identifying genes that could be used to provide better protection of crops against insects, weeds and diseases. Research in this area includes the discovery and testing of genes that produce toxins that either kill insects or inhibit their growth. Other projects have identified genes in the insects themselves that may be used to provide broadspectrum protection against fungal diseases of grains crops.

The GPG team is also developing methods for removing the mycotoxins produced as a result of fungal spoilage that reduces the economic value of stored grains.

In a joint project with the International Crops Research Institute for the Semi Arid Tropics (ICRISAT), resistance genes to Helicoverpa in wild relatives of commercial chickpea species are being investigated. Molecular markers to indicate the presence of these chickpea resistance genes are being developed to assist with breeding.

The group is also studying natural plant resistance to Russian Wheat Aphid, which is not yet in Australia but, according to Dr East, will inevitably arrive. Quarantine restrictions mean this research is being done in the CSIRO Montpellier laboratories in France, where researchers are testing the effectiveness of the known plant resistance genes against all the known biotypes (strains) of the aphid. With this knowledge, the researchers will be able to advise on the best resistance genes to include in breeding programs.

Alongside the pest insect-plant relationship, the program"s commercial aim is to develop Australian intellectual property that has been tested and found appropriate for the Australian environment but is also valuable to other industries around the world.

"If we develop a product that overseas industries need, and that a global company is keen to acquire it, then we have some leverage with which to buy other technologies that we need," says Dr East.

Towards this end, the group has patented a set of insect antifungal genes, which may be of particular use in areas of the world that are cooler and wetter than Australia and have greater problems with fungus. The group is also in the final stages of testing antifungal genes, and genes that inhibit pest insect growth that have been transferred into plants grown in controlled laboratory conditions.

The program is in the third year of a five-year plan, and includes commercial and legal expertise to ensure that the research outcomes are jointly owned by CSIRO and GRDC.

GRDC Research Code CSE193
For more information: www.ento.csiro.au