New genetic resources will aid ongoing fight against yellow spot

CCDM researchers Caroline Moffat, left, and Paula Moolhuijzen worked jointly on a project that has resulted in the development of a high-quality reference genome that will be used to discover fungal toxins and other genes important in yellow spot disease. Photo by CCDM

Researchers at the Centre for Crop and Disease Management (CCDM) have developed new genetic resources with the aim of better understanding the damaging yellow spot fungal pathogen in Australian wheat crops.

Using yellow spot samples from Australia and overseas, they have sequenced the genomes – or complete DNA sets – of new fungal isolates, which is set to help researchers make new discoveries into the cause and impact of yellow spot disease (caused by the fungus Pyrenophora tritici-repentis), also known as tan spot.

Researchers at the Perth-based CCDM – a national research centre co-supported by Curtin University and the Grains Research and Development Corporation (GRDC) – sequenced DNA from yellow spot samples from Australia, the US and Canada, with the aim of improving the scientific resources available for studying this globally significant wheat pathogen.

According to CCDM yellow spot program leader Caroline Moffat, the research resulted in the development of a high-quality reference genome that has greater relevance to the work of Australian researchers.

“Genome sequences are powerful research tools, enabling us to understand how particular pathogens cause disease,” Dr Moffat said.

“The CCDM team have uncovered genetic features that have not been seen before, and this will go a long way in helping us to discover fungal toxins and other genes important in yellow spot.

“This pathogen has many weapons and the genome sequence is the key to finding and thwarting its effects through the release of yellow spot resistant wheat varieties.”

To date, Australian researchers have used an American reference genome to study yellow spot. But with isolates in Australia differing to those found overseas, this new high-quality Australian genome will provide a much better understanding of the genetic make-up and influence of the damaging disease.

“This will allow researchers to be more effective in their ability to understand and tackle yellow spot,” Dr Moffat said.

“While dry conditions experienced in autumn across many of Australia’s cropping areas mean 2018 may not be a high risk year for the disease, it is one of the country’s most significant wheat diseases with average annual yield losses worth more than $200 million.”

In the genome study, CCDM researcher Paula Moolhuijzen used advanced DNA sequencing techniques and data analytical tools (bioinformatics) to generate and assemble the genome for eight yellow spot isolates, including a new race or ‘group’.

One isolate, collected from Meckering in Western Australia’s grainbelt, was then optically mapped and genetic material was ordered into chromosomes, enabling her to identify important DNA features that had not been seen before.

“This new genome revealed a number of differences to those previously available from America and is a positive step in the genetic study of yellow spot, not only in Australia but globally as well,” Dr Moffat said.

“This work brings to the table a new high quality reference genome and we look forward to researchers being able to utilise this resource to accelerate their work, and pinpoint the cause of losses from this fungal disease.”

A research paper, outlining the CCDM finding, called Comparative genomics of the wheat fungal pathogen Pyrenophora tritici-repentis reveals chromosomal variations and genome plasticity, has been published in the BMC Genomics scientific journal.

Source: CCDM

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