Queensland Department of Primary Industries researchers have found a way of using DNA tags to combat a rapidly evolving sunflower disease.

DPI sunflower plant pathologist Gary Kong and biotechnologist Wendy Lawson are using DNA tags to build gene pyramids that provide sunflower plants with better resistance to rust than previous methods.

Through prolonging the productive lives of sunflower hybrids, the technology will financially benefit seed companies, growers and consumers.

Dr Kong said the research in which he and Dr Lawson were involved was a result of a potential worsening sunflower rust situation in Australia.

"It has become very complex with the rapid appearance of new infective rust races.

"This has resulted in the systematic loss of resistance in commercial hybrids as new races appear," he said.

Dr Kong said although there had not been widespread epidemics of rust due to many years of drought, the rust pathogen was evolving on wild and volunteer sunflower plants in remote areas of Australia.

"Any return to favourable seasons and large plantings of sunflower will lead to the kind of severe rust problems we experienced in the 1980s."

With support from the Grains Research and Development Corporation and the CRC for Tropical Plant Pathology, he and Dr Lawson had systematically studied the patterns of changes in the rust population and developed a strategy of combining specific resistance genes in sunflower that could potentially "block" the rust, he said.

"The strategy is commonly known as gene pyramiding, and involves combining two or more key resistance genes into a single line.

"The process ranges from extremely difficult to impossible using traditional breeding techniques.

"However, by developing DNA tags for specific resistance genes, we can track the genes as they are incorporated into the same line."

Dr Kong said if a range of different gene pyramids was incorporated into commercial cultivars, the prospect of new races evolving would be greatly diminished.

"It's like an investment portfolio and not putting all your eggs in one basket, but we're only investing in blue-chip resistance genes."

Because the technology allowed complex gene pyramids to be assembled more quickly than was previously possible, there is also a greater capacity to respond should new races appear, he said.

"To follow the share analogy, if there is a market crash, we will be ready."

Dr Kong said they were now ready to apply this technology through direct collaboration with seed companies, resulting in more-robust and longer lasting resistance in commercial hybrids.