Electrified insects key to wheat production
Research by CSIRO scientists aims to breed legumes
resistant to fungus and aphids, which will help boost
Australian wheat yields.
Image: iStockphoto

Crop rotation is vital to wheat farming. By alternating their wheat planting with legumes, farmers are able to fix and replenish nitrogen in the soil, resulting in greater wheat yields the following year.

As an added benefit, legumes are mostly unaffected by the diseases and fungi that attack wheat and cereals. They are however, still susceptible to losses from their own types of diseases and pests.

Many growers have lately been losing confidence in legumes due to increasing losses from aphids and fungus.

“Rather than looking at all of the different legumes and all of the different diseases, we decided we’d focus our resources on the Medicago Truncatula legume,” says Dr Anderson.

Medicago Truncatula is the ‘fruit fly’ of legume biology.

It grows to maturity quickly, its genome has been completely sequenced, and it shares common factors with other legumes from all around the world.

Dr Anderson was able to locate a gene on the Medicago genome that confers a high level of resistance to pea aphids.

“We analysed aphids feeding on resistant plants to find where the resistance mechanisms were,” he says.

“We tested this by gluing a fine gold wire onto the back of the aphid and putting the other end in the ground.

“When the aphid puts its mouthparts in the plant, that completes the electrical circuit, and we can analyse the resistance to see what the aphid is doing.”

Dr Anderson is now researching the genetic pathways to find out how the plant’s anti-aphid response works.

Dr Anderson has also been looking into resistance to the fungus Rhizoctonia Solani, a potent disease that can survive in soil for years.

There are no crops that are completely resistant to Rhizoctonia, and it affects both cereals and legumes.

“We found that some types of Medicago have a moderate resistance, and some others have severe sensitivity,” says Dr Anderson.

Looking at the difference between these strains, Dr Anderson has found a particular family of genes that appear responsible for defence against this fungus.

A breeding program is underway in South Australia to create a resistant strain of Medicago.

Resistant strains of legumes will mean more nitrogen in the soil, less aphids surviving year to year, and fewer fungal spores to attack wheat crops. 

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