Protecting crops

Cabbage and cauliflower and their close relatives like bok choi, broccoli and Brussels sprouts are the most important dietary leafy vegetables in China, India and much of Asia, and make up a significant share of rural food budget incomes.

Most cabbage and cauliflower crops in Asia are sprayed with toxic insecticides at least six times before they reach the market, but awareness of the risks of pesticide residues on vegetable crops is growing rapidly.

As an alternative to traditional insecticides, caterpillar control in genetically modified crops such as cotton and maize has demonstrated massive financial, environmental and human health benefits globally. However while this approach has been highly successful against caterpillars, sap-sucking aphids and allied insects remain a major hurdle in the production of many food crops.

Drought, exacerbated by global warming, enhances the impact of insect pests and that of the numerous viruses they transmit, while resistance to conventional insecticides is increasing rapidly.

The new collaborative research project titled ‘Crop Plants Which Remove Their Own Major Biotic Constraints’ aims to produce plants that control pests (biotic constraints) themselves, without the need for pesticides. The team will use a novel approach to provide commercially important crop plants with the ability to express non-toxic molecules capable of suppressing aphids as well as the improved capacity to control caterpillar pests.

The approach involves identifying genes in aphids which code for proteins necessary for vital life functions in aphids only. These genes (DNA) produce molecules called RNA which carry the DNA instructions out of the nucleus and to the cell’s protein-making machinery. The project will synthesise artificial RNA which will bind to the aphid RNA molecule and inactivate it, thus preventing the vital proteins from being made, and so killing the aphids. These aphid controlling genetic sequences will be combined with the known genes which control caterpillars and the whole genetic construct will be inserted into the crop plants. The resulting insect resistant plants will then be provided to the seed industries in India for use in cabbage and cauliflower, and in Australia for canola.

The Australian research team is led by the University of Melbourne’s Professor Prem Bhalla, from the Melbourne School of Land and Environment and will be complemented by CSIRO and the University of Queensland.

The project has received $3 million from the Federal Government in Australia with a matching sum from the Department of Science and Technology in India and will be managed by adjunct Associate Professor Derek Russell from the Department of Genetics and the Bio21 Institute.

Australian researchers will work closely with an Indian team from the International Centre for Genetic Engineering and Biotechnology, the National Research Centre for Plant Biotechnology and the Indian Agricultural Research Institute.

“India is the world’s largest grower and consumer of cauliflower and cabbage (64 million tonnes a year) and cauliflower in particular is a major dietary item for a billion people,” says Dr Russell.

“About a third of the national crop is lost to insect pests despite about 30 per cent of the total costs of producing the crop being spent on buying and applying insecticides,” he explains.

“This technology has the capacity to remove all that expenditure and human and environmental health impact and greatly reduce the price of these key foods in this significantly vegetarian country.

“For Australia, one of the world’s major canola growers and exporters, insect control in canola is a key element in the costs of production, but insect attacks are sporadic and unpredictable, so this technology can remove the need for costly monitoring and control of the key pests and reduce the environmental footprint of the crop.”

We tend to think of grains such as rice, wheat and maize, and legumes such as peas and beans when we think of global food security, but the World Health Organisation is heavily promoting vegetables and their oils as important in healthy diets across the planet.

The Genetics Department at the University of Melbourne will take the lead in developing and testing the genetic constructs which will provide novel resistance to aphids and the Department of Food and Agriculture Systems will then introduce the genes into canola and test them against key pests.

If successful the intention would be to transfer this knowledge for use in wheat and other crops. This could be a paradigm changer for aphid control worldwide.

www.land-environment.unimelb.edu.au