La Trobe University scientist, Dr Rachel Mann, has developed a new diagnostic

test for the major horticulture disease fire blight. Fire blight is not currently

present in Australia, but has proved devastating to pear and apple industries overseas.

Fire Blight is a disease that is caused by bacteria that affects apples and pears

and what is does it gets into the plant usually through the blossoms or through any

natural openings and it moves through the tissue and kills the tissue as it goes

through and you end up getting dead blackened leaves, and shoots and limbs from the

tree and it looks as though it has been scorched by fire, and that's why its called

fire blight.

Fire blight is one of Australia's major biosecurity threats and Dr Mann's

research is set to revolutionise screening procedures across the world.

The research in this project was based on improving diagnostic tests for fire

blight. This was done with my supervisors, Dr Kim Plummer and Dr Brendan Rodoni.

The aim was really to improve testing at the border to make sure that the tests were

not missing bacteria where plant material was being imported into the country.

Additionally, we want to use these tests for surveillance to prove we don't have

the disease in our apple and pear growing regions, or in the country as a whole.

The genetic makeup of fire blight was largely unknown prior to Dr Mann's work, so

the first step in developing a diagnostic test involves sequencing the DNA of the bacteria.

So what we have done to develop the test is we've sequenced the genomes or genetic

maps of lots of different strains of the fire blight causing bacteria and we've

compared those genomes to genomes of closely related bacteria and a whole array of

other bacteria. What we've done we have identified unique DNA signatures that are

only found in the fire blight bacteria. We take a small piece of plant tissue, and we

extract all the DNA from that sample and then we put in specific probes that are

looking for those unique signatures that are only found in the bacteria, so if the

plant sample has the bacteria, we get a positive result.

Dr Mann is one of ninety La Trobe University researchers working in the new Centre

for AgriBioscience. AgriBio was officially opened in April 2013, and is a joint

collaboration between La Trobe University and the Victorian Department of

Environment and Primary Industries.

It's about protecting agriculture production from disease, but also about

making sure we increase productivity to meet the demands of an expanding global population.

The research underway at AgriBio is not only important for Australian

agriculture, but will have international significance.

So we're hoping that these diagnostic tests will become an international

standard for testing of fire blight, and this will help prevent the movement of

fire blight globally. It's also important for Australia to maintain its fire

blight free status because having this disease would affect our markets into

certain countries.

Dr Mann will now turn her attention to developing diagnostic tools for a range of

other diseases threatening the horticultural sector.

The methods that we used to develop the test for fire blight are currently being

used in a new project with CRC for Plant Biosecurity, to develop tests for other

plant pathogenic bacteria of high biosecurity risk to Australian plant industries.

Dr Mann's research won the prestigious Nancy Millis Post Graduate Thesis Award in

2013, it's an example of the collaborative work being undertaken at AgriBio

between the Department of Environment and Primary Industries and La Trobe University.