Characterization of rice blast races present in Australia

AgriFutures Australia - Vincent Lanoiselet

Type: Research Paper
Knowledge level: Advanced

Farm Table says:

This report provides the first knowledge about races of rice blast occurring in northern Australia, and highlights a high level of virulence variability among Australian rice blast isolates

What is the problem?

Rice blast caused by the fungal pathogen Magnaporthe oryzae is the most serious disease threat to rice
production worldwide. In Australia, to date rice blast occurs in northern Australia, including northern
Queensland, Northern Territory, and northern Western Australia, but remains exotic to south-eastern
Australia where most of the Australian rice is produced. There is the potential for rice blast to threaten
the rice industry in south-eastern Australia; in addition, rice industry in Australia is considering the
establishment of new production areas in northern Australia, which makes rice blast a big concern to
rice research and development in Australia, especially the recent outbreaks of rice blast across northern
Australia.

This project investigated the race’s status of rice blast isolates from northern Australia as well as their distributions and phylogenetic.

What did the research involve?

A set of International Rice Blast Monogenic Lines (IRBL) with 25 targeted resistance genes were
imported from the International Rice Research Institute (IRRI), including the Pi40 gene that has shown
broad-spectrum resistance to rice blast in other Asian counties and Africa. The disease reactions of the
monogenic rice lines to different races of rice blast in Australia were investigated under controlled
environmental conditions at the glasshouse of the University of Western Australia.

The representative Australian and international rice varieties with origin from different countries were
determined for their disease responses to different races of rice blast in Australia under controlled
environmental conditions at the glasshouse of the University of Western Australia.

A field survey for rice blast and other fungal diseases in wild rice and cultivated rice was conducted at
a number of locations in the Cairns and Mareeba regions of northern Queensland in 2014, and the
fungal isolates were identified by morphological examinations and molecular sequencing.

The host ranges of rice blast isolates on cereal crops as well as grass weeds were determined under
controlled environmental conditions.

Different carrier materials were used to determine the maximum period of viability for spores of rice
blast.

What were the key findings?

  • The rice blast isolates collected across northern Australia were characterized by five races
  • All the rice blast isolates collected from northern Australia clustered into a clade along with all
    reference rice blast isolates from other counties.

Among the monogenic rice lines with 25 targeted resistance genes

  • genes Pi40, Piz-t, Pi5(t), Pi9 and
  • Pi12(t) exhibited resistance to all rice blast races
  • in particular, gene Pi9 showed complete resistance to all isolates of races IA-1, IA-3, IA-63 and IB-3.
  • Another three genes Pi7(t), Pik-m and Pita2 showed resistance to all isolates of races IA-1, IA-3, IB-3 and IB-59
  • in particular, gene Pita2 had complete resistance to the three races IA-3, IB-3 and IB-59.
  • Genes Piz, Pit, Pi1, Pi3 and Pita only exhibited completed resistance to race IA-3.

Across the rice varieties,

  • SHZ-2 exhibited a resistant disease reaction to all isolates of the five rice blast races.
  • Another five varieties, NTR 587, BR-IRGA-409, Ceysvoni, Rikuto Norin 20 and Kyeema,
    exhibited a resistant reaction to at least three of the five races,
  • where NTR587 was resistant to races IA-3, IA-63, IB-3 and IB-59, and with a moderate resistance to race IA-1; BRIRGA409, Ceysvoni and
  • Rikuto Norin 20 also showed a resistant reaction to races IA-3, IA-63, IB-3 and IB-59;
  • there was a resistant reaction of Kyeema to races IA-3, IB-3 and IB-59
  • and a moderate resistance to race IA-63.
  • In general, Quest and Yunlu 29 were the most susceptible varieties to the rice blast races.

The field survey in northern Queensland revealed a diverse range of fungal species, including important pathogens of cultivated rice. Apart from the isolate of M. oryzae obtained from wild rice, Bipolaris oryzae (causal agent of brown spot) was the predominant pathogen detected under North
Queensland conditions.

Other pathogens detected on wild rice included Rhizoctonia oryzae-sativae (causal agent of aggregate sheath spot on rice), Curvularia lunata, Cochliobolus intermedius, Cochliobolus geniculatus, and Fusarium equiseti. In addition, it was demonstrated that B. oryzae isolated from wild rice in Australia can infect cultivated rice and cause severe brown spot disease.

Under experimental conditions, other cereal crops such as wheat, barley and maize can serve as the hosts of rice blast pathogen, especially barley. The rice blast pathogen can also infect grass weeds, including wild oat, ryegrass and Phalaris.

Fabric was the best carrier material for the spread of M. oryzae spores across all the carrier materials and temperatures tested.

Final comment

The findings of rice varieties with resistance to specific and/or multiple races of rice blast in Australia will enable rice growers to choose the varieties they can deploy to minimise losses caused by rice blast. In addition, the resistance sources will allow breeding programs to develop rice varieties with resistance to specific and/or multiple races of rice blast in Australia.

2016 - Australia - AgriFutures Australia - Vincent Lanoiselet
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About the Organisation

Name: AgriFutures Australia
Email: belinda.allitt@agrifutures.com.au

AgriFutures Australia is a new beginning for the Rural Industries Research and Development Corporation. We are an organisation that proudly focuses on the future of Australian agriculture. We live and work in the regions and represent the interests and aspirations of farmers and rural communities.

Our vision is to grow the long-term prosperity of Australian rural industries. In practical terms, this means:

Initiatives that attract capable people into careers in agriculture, build the capability of future rural leaders, and support change makers and thought leaders.
Research and analysis to understand and address important issues on the horizon for Australian agriculture.
Research and development for established industries that do not have their own Research & Development Corporation (RDC), including the Rice, Chicken Meat, Honey Bee and Pollination, Thoroughbred Horse, Pasture Seeds, Export Fodder, Ginger and Tea Tree Oil industries.
Research and development to accelerate the establishment and expansion of new rural industries, such as Deer, Buffalo, Kangaroo and Camel Milk.

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