Australian researchers have developed a new way to breed disease-resistant wheat, and say there appears to be no downside to the technique.

A team from John Curtin University and independent research provider Kalyx Australia says it has a possible solution for the large-scale damage caused by Yellow Spot fungus.

The group has demonstrated that by taking away disease-sensitivity genes from the wheat germplasm, pathogens find it difficult to latch onto wheat and cause damage.

“Our finding will help breeders produce crops in which disease losses are 60 to 80 per cent lower, and would be a real win for farmers – they will often be able to avoid using foliar fungicides,” said Professor Richard Oliver, Director of the Australian Centre for Necrotrophic Fungal Pathogens (ACNFP) at Curtin.

“Before now, breeding for resistance to Yellow (Tan) Spot and Septoria Nodorum Blotch was very time-consuming – no molecular markers were in use. The key has been to supply breeders with specific proteins (we call them effectors) that the fungi use to cause disease.

“For the first time, our technology allows for a steady and sustained improvement in disease resistance without affecting the farmer’s pocket,” he said.

According to researchers’ estimates; farmers can lose more than 0.35 tonnes per hectare in wheat yields to Yellow Spot, even after applying fungicide. On a farm of 4000 hectares, it could mean $500,000 is lost to disease per year – or about $212 million worth of damage to the wider industry.

Investigations began with comparisons of existing wheat cultivars, looking at yield loss when subjected to natural disease and stress pressures. They indentified particular disease-sensitivity genes and showed than when these were lacking, there was no yield loss. In some instances, yields even increased in the presence of disease.

From this, the team were able to conclude if a sensitivity gene was eliminated, there would be minimal associated risks and it would be a safe and straightforward strategy for improving disease resistance.

“Previously geneticists would infect plants that were progeny of crosses between relatively resistant and relatively susceptible parents before doing the QTL (quantitative disease-resistance gene) mapping. But as disease resistance is multifactorial due to the several effector reactions, the QTL mapping was always a bit fuzzy and was therefore never passed on,” Professor Oliver said.

“Our research looks directly at the loci that recognise the pathogens, which can be readily identified using a process we developed earlier, thereby bypassing the need for QTL mapping.”

More details can be found in the full report, available here.