Breeding resistance to Russian wheat aphid
Russian wheat aphid (RWA) is one of the most serious grain pests and has devastated crops in every major grain-growing region of the world outside of Australia. While Australia has so far managed to keep the pest from its shores, the GRDC has made a major investment in a pre-emptive breeding program as part of a ‘preparedness’ strategy against a potential incursion.
Associate Professor Mehmet Cakir, of Murdoch University in Western Australia, is leading a team of scientists that has helped identify key genes offering broad resistance to RWA and integrate these into some of Australia’s most popular wheat and barley varieties. These include Wyalkatchem, EGA Gregory and Correll wheat and the barley varieties Vlamingh and Hindmarsh.
Associate Professor Cakir says unlike most aphids that need to swell to large numbers before they affect production, the effects of RWA would be seen almost immediately in the event of an incursion.
“The aphid injects a toxic saliva into host plants, causing chlorosis, leaf rolling, reduced biomass, deformed flag leaves and trapped heads. It would take only a small population of this devastating insect to inflict significant damage in Australia.”
RWA is estimated to have caused more than US$800 million (A$782 million) of direct and indirect losses in the US in the first seven years following its arrival in 1986.
Associate Professor Cakir leads a team of researchers from CSIRO and the Queensland Department of Agriculture, Fisheries and Forestry and international collaborators from the US, France, Argentina, South Africa, Kenya, Ethiopia, Turkey and the International Center for Agricultural Research in the Dry Areas (ICARDA).
While all Australian wheats and barleys have proven susceptible to the disease, some international lines have shown resistance to the effects of the aphid’s toxins. The GRDC has funded Associate Professor Cakir’s research to better understand the genetic basis of this resistance and use the findings to develop RWA-resistant varieties suited to Australian conditions.
Resistant varieties have been sourced from the US, Kenya and South Africa, as well as from international seed collections at the International Maize and Wheat Improvement Center in Mexico and ICARDA in Syria.
Associate Professor Cakir has characterised as many as 100 resistant wheat and barley lines in the past few years to identify lines with broad resistance. The process has been complicated by the discovery of multiple biotypes of the aphid during the past decade. This has meant testing resistance against RWA insects from a range of countries including the US, Mexico, France, South Africa, Kenya, Turkey, Syria and Hungary to make sure the Australian varieties are fully protected.
“We have been looking for lines with broad resistance to multiple strains of RWA because we can’t predict which strain may establish in Australia. Since RWA is not in Australia, our ongoing collaboration with other countries is essential to the testing process.”
Molecular markers for resistance genes have also been identified and these have been made available to Australian breeding companies for marker-assisted breeding.
Associate Professor Cakir said results of the pre-emptive breeding program offered hope that the Australian grains industry would be protected from the worst effects of a RWA incursion in the future.
Similar research is now being planned for other grains biosecurity threats such as Sunn pest, hessian fly, green bug and Karnal bunt, which have been identified as high-risk threats to Australian grains.
Associate Professor Mehmet Cakir
08 9360 6640
GRDC Project Code NPB00008
Region National, Overseas, North, South, West