Australia
December 20, 2011
Research by local and international researchers has given plant breeders another tool to fight the fungal wheat disease commonly known as septoria, which causes annual losses exceeding $100 million in Western Australia.
A protein called 'Tox1' produced by Stagonospora nodorum, which causes Stagonospora (also known as septoria) nodorum blotch, has been cloned so it can be used by wheat breeders to help screen new breeding lines for their susceptibility to the disease, and produce varieties with better resistance.
The cloning was achieved by scientists at the Grains Research and Development Corporation (GRDC) supported Australian Centre for Necrotrophic Fungal Pathogens (ACNFP), based at WA’s Curtin University, and colleagues at the Australian National University and in the United States.
ACNFP director Richard Oliver (photo) said the cloning of Tox1 could help produce a septoria-resistant replacement for the WA noodle wheat variety Calingiri, which is moderately susceptible to the disease due to its sensitivity to Tox1.
Professor Oliver said the cloning of Tox1 was the latest in a series of achievements made in septoria research in recent years.
“Progress in combating septoria has really taken off in the six years since the GRDC began funding research into the genome sequence associated with the disease,” he said.
“The research achievements have significantly reduced the time it takes breeders to select disease resistant lines, and has allowed them to concentrate more resources on other desirable traits.
“Already in 2011, WA growers’ productivity has increased by $20 million due to their adoption of new wheat varieties insensitive to protein toxins produced by septoria.”
Professor Oliver said Tox1 was one of a small number of proteins, called effectors, secreted by septoria.
“Our research has shown that septoria causes disease on wheat by producing effectors, which interact with specific wheat proteins present in some varieties and not in others,” he said.
“If a particular type of wheat protein is present in the variety, the effector causes ‘necrosis’ – the premature death of cells in the plant tissue – which enables the septoria fungus to enter the plant and cause disease.
“The amount of disease is roughly proportional to the number of effectors the fungus has, for which the cultivar has the specific receptors.
“The task of the plant breeder is to remove those wheat genes which cause sensitivity to the effectors.”
Professor Oliver said about 100,000 doses of two effectors – known as ToxA and Tox3 – had already been delivered to Australian wheat breeders in recent years, for use in testing the susceptibility of new wheat lines to septoria.
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