From lab to field: Breeding-out Australia’s ‘most costly’ wheat disease
‘Deleting’ a crucial gene in the yellow leaf (or tan) spot pathogen which causes wheat plant cell death has led to significant cost-savings and increased wheat yields throughout Australia over the last five years, according to Dr Caroline Moffat from Australia’s Curtain University.
“Yellow spot disease is arguably the most costly disease to Australian wheat growers in terms of yield loss,” she told Milling & Grains.
Yellow leaf spot (or Pyrenophora tritici-repent) attacks wheat crops at an early stage in development and manifests as tan spots on the leaf surface, eating away at the plant cells. It is one of the most damaging wheat crop pathogens in Australia, and particularly in Western Australia and northern cropping regions, she said.
“Annual losses to yellow spot have been reported at AUS$212 million, plus control costs of $46m per annum. Western Australia is worst affected with annual losses of $140m.”
Moffat’s research team has managed to ‘delete’ the main host-selective ToxA toxin (or effector) in yellow spot fungus which is helping breeders develop resistant wheat strains. The research has also enabled scientists to identify other harmful molecules.
"Deleting a gene is a research technique that serves as a powerful tool to help researchers determine the biological role of a particular gene of interest, but this is the first recorded gene deletion in the yellow spot pathogen," she said.
As a result, adoption of ‘effector-assisted breeding’ has been rapidly expanding in Australia, she added.
The areas sown with ToxA-sensitive varieties has declined and productivity increased with knock-on ‘multi-million dollars’-worth of savings, she said.
“Through identifying and deleting the ToxA gene from the fungus, we have removed subsequent induced cell death (or necrosis). It has also enabled us to see what other host-selective toxins the fungus produces, which were previously masked.
“This is a great example of research moving out of the laboratory and into the field, where it is impacting industry.”
Host-selective toxins only damage wheat varieties that possess the corresponding sensitivity gene and by identifying new toxins, breeders can ensure future wheat lines are not vulnerable to these other ‘pathogen effectors’ using traditional breeding techniques, said Moffat.
“There are at least two other host-selective toxins, but we believe additional unidentified ones exist.”
Moffat’s research has the potential to be applied to other yellow leaf spot pathogen hot-spots around the world, including North and South America, Europe, Asia, the Middle East and parts of Africa.