Western Australian research to bolster yellow spot resistance of wheat varieties

Western Australian researchers have identified new genetic material which wheat breeders can use in coming years to strengthen the resistance of new varieties against yellow spot disease.

Department of Agriculture and Food WA (DAFWA) scientists have identified the material in collaboration with researchers from The University of Adelaide and Victoria’s Department of Primary Industries under a Grains Research and Development Corporation (GRDC) funded project.

Yellow spot, also known as tan spot, is a damaging foliar disease in wheat and can cause yield losses greater than 50 per cent in seasons when conditions are favourable for disease development.

In WA, yellow spot causes average crop losses of $140 million annually, and the cost of controlling the disease in the State is $209 million annually.

DAFWA senior plant pathologist Manisha Shankar said yellow spot had been widespread in the WA grainbelt in 2011.

She said relatively few yellow spot resistance genes had previously been identified and mapped in Australian germplasm, and only one gene – tsn1 located on the 5BL chromosome – was in general use in Australian wheat breeding programs.

"Since starting work on this GRDC funded ‘pre-breeding’ project in 2010, our research team has found five ‘chromosomal regions’ – or genes other than tsn1 – which confer resistance to yellow spot,” Dr Shankar said.

"Some of these genes appear to be novel (previously not reported).

"We are now working to ‘stack’ two or more of these genes in combination with tsn1 to develop higher levels of resistance that can be deployed into future varieties.”

Dr Shankar said the research had also identified novel yellow spot resistant germplasm among lines imported from the International Centre for Agricultural Research in Dry Areas (ICARDA) and the International Maize and Wheat Improvement Centre (CIMMYT), through the CIMMYT-Australia-ICARDA Germplasm Evaluation (CAIGE) project.

"These ICARDA and CIMMYT lines will help us identify additional resistance genes to further enhance resistance,” she said.

"Also, if genes ‘stacked up’ in breeding lines are from diverse material, the yellow spot pathogen may take longer to evolve against them and break down the genes.”

Dr Shankar said researchers at DAFWA and Queensland’s Department of Employment, Economic Development and Innovation (DEEDI) were also developing new technology which would speed up screening processes used by plant breeders to identify yellow spot resistance levels in adult plants.

"Currently, this screening is carried out in the field and takes place when the wheat plant reaches maturity,” she said.

"By exposing plants to continuous light in the glasshouse, plants are reaching maturity much more quickly, and under these controlled conditions plants have produced flag leaves within four to six weeks.

"The levels of yellow spot resistance in adult plants grown under these conditions can be easily distinguished much earlier, and these methods will greatly improve the efficiency of breeding for adult plant resistance to the disease.”