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The holy grail for disease resistant barley

It’s just like that Hunters and Collectors song…. “Yeah we razed four corners of the globe …..for the holy grail…..”

Our barley powdery mildew team has literally searched four corners of the globe for powdery mildew resistant barley and were successful at finding an exceptional resistance within an Ethiopian barley line that provides immunity to all forms of barley powdery mildew.

Furthermore, and unlike related resistance in barley, this one doesn’t cause tissue damage, which means no yield penalty – the first significant breakthrough in barley powdery mildew resistance in over 40 years. “We were full of beans” (but thankfully we weren’t “dying like flies”).

Cynthia and Simon
Cynthia Ge and Simon Ellwood with the Ethiopian barley landrace

Barley powdery mildew researcher Simon Ellwood said this discovery will be very advantageous to Australian barley growers, with powdery mildew resistant barley cultivars now in the pipeline.

“For many years barley powdery mildew has been a headache for growers, particularly because of a lack of durable resistance that doesn’t break down and varieties favourable to malting companies, such as Baudin, being susceptible,” Simon said.

“Add to that the development of fungicide resistance first discovered in 2009 in WA and more recent discoveries in other states by my colleagues.

“For some time we have been screening exotic barley lines from other countries – Uzbekistan, China, Turkey and so on – trying to find genes with durable resistance that could be introduced to Australian barley lines, and at last, we found a promising resistance within an Ethiopian barley line.”


Introducing Eth295 – a barley gene from Ethiopia

Resistance to powdery mildew has always been a tough one for breeders. When introducing a resistance gene into barley, it’s often not long before the pathogen mutates to overcome the resistance, and is able to infect the plant again.

Some 40 years ago there was the discovery of the mlo-11 mutation, which to this day holds the best genetic resistance to barley powdery mildew. It has been widely deployed in Europe and the US and was recently introduced into Australian barley varieties such as Grange and Westminster.

“However, while successful at preventing powdery mildew, mlo-11 has been shown to reduce yields by causing necrosis (cell death). Breeders need to combine mlo-11 with other genes to help reduce tissue damage,” Simon said.

“Our Eth295 is a variant of mlo-11. This variant is structurally different and does not possess known deleterious effects of all mlo alleles and, therefore, does not affect yield.

“Eth295 is the first naturally occurring variant of mlo-11 discovered to date with advantageous characteristics – and we’re pretty excited to introduce the gene into Australian barley germplasm.”

holy grail


So what will this mean for barley growers?

In the next few years, barley growers will soon have varieties that are very similar to the popular Baudin in every other way, but with far more resistance to barley powdery mildew.

Simon said his team are now bulking up seed of lines containing the new resistance for breeding companies, to ensure the gene is included in their up-and-coming barley lines.


At a time when fungicide resistance emerges in the east

This resistance gene could not come sooner, especially as resistant populations of powdery mildew in barley begin to emerge in the eastern states, with cases recently detected in NSW, Victoria and Tasmania from last season’s samples.

Meanwhile, WA growers continue to battle with control of the disease, with the massive outbreak of tebuconazole resistance in 2009 limiting their control options.

“From last season’s samples, we are seeing high levels of resistance against DMI fungicides such as tebuconazole from across the country, which means growing resistant varieties is now more important than ever for improving growers’ returns,” Simon said.

Where barley powdery mildew resistance to DMI fungicides has set in
Where barley powdery mildew resistance to DMI fungicides has set in

Mildew Mania! How kids help us to do our job better

Mildew Mania is a citizen science project that gives WA students an opportunity to engage in CCDM research. Students are shown how to sample powdery mildew on different varieties of barley and send us the samples.

It allows us to receive samples from all over WA, providing a cross-section of what’s actually out there. Consequently we are able to keep better track of the disease and watch for the development of new pathotypes, as well as monitoring resistant barley varieties that retain their resistance.

Mildew mania2


The paper

This research was recently published in Nature Scientific Reports, and can be found here: www.nature.com/articles/srep29558

About SimonSimon Ellwood

Simon joined Curtin University in 2010 and has always had an interest in improving genetic resistance to plant fungal pathogens.

His research has focused on improving both cropping and pasture yields for the agricultural industry. He now focuses all of his time on the two major diseases of barley; powdery mildew and net-type net blotch.

 

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