Based on historical data, Australia and New Zealand (NZ) form a single epidemiological unit for cereal rusts. Until 2001, pathotype analysis of cereal rust pathogens for NZ was conducted at the University of Sydney, Plant Breeding Institute. The first year of pathotype analysis in New Zealand provided evidence for pathotype exchange in both directions across the Tasman. The second year of pathotype analysis has provided more detail on the evolution of rust pathotypes within New Zealand. From these results a fuller picture of the pathotype diversity of New Zealand cereal rusts is emerging with important consequences for the cereal industry in both New Zealand and Australia.

1. biosecurity built on science
Reconstructing history: insights into Australasian
cereal rust evolution and dispersal since 2001
Will Cuddy
Plant pathologist, NSW Department of
Primary Industries
Plant Biosecurity Cooperative Research Centre

2. biosecurity built on science
 Robert Park, Plant Breeding Institute, the University of Sydney
 Soonie Chng, The New Zealand Institute for Plant and Food Research
Limited
 Rachael Warren, The New Zealand Institute for Plant and Food Research
Limited
The team

3. biosecurity built on science
The history
 Historically, the pathotype analysis of New Zealand cereal rusts was
conducted at the Plant Breeding Institute, Cobbitty (University of
Sydney)
 Stopped in 2001 due to changes in quarantine laws
Puccinia triticina (Pt)Puccinia striiformis
f. sp. tritici (Pst)
Puccinia hordei (Ph)

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How do we determine pathotypes?
 Samples of cereal rusts from the paddock are inoculated onto a series of
seedlings.
2002
134 E16 A+
2006
134 E16 A+17+
Resistant Susceptible

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How do we determine pathotypes?
 Samples of cereal rusts from the paddock are inoculated onto a series of
seedlings.
 http://sydney.edu.au/agriculture/plant_breeding_institute/cereal_rust/
reports_forms.shtml

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 Pst
Where we were up to in 2015
134 E16 A+
134 E16 A+ J+
+YrJ+Yr10
150 E16 A+
134 E16 A+ J+ 27+
Australia
+YrT +Yr27
150 E16 A+ J+
+Yr10
134 E16 A+ J+ T+
134 E16 A+ J+
New Zealand
Puccinia striiformis
f. sp. tritici (Pst)

7. biosecurity built on science
 Pst in New Zealand is facing different selection pressure to Pst in
Australia
What new knowledge do we have in 2016?

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 Pt
Where we were up to in 2015
Puccinia triticina (Pt)
Australia New Zealand
76-3,5,7,9,10 +Lr37
76-3,5,7,9,10,12 +Lr37
+Lr17b
76-3,5,7,9,10,12,13 +Lr37
+Lr24
76-1,3,5,7,9,10,12,13 +Lr37
+Lr20
76-3,5,7,9,10,12,13 +Lr37
76-1,3,5,7,9,10,12,13 +Lr37

9. biosecurity built on science
 Pt
Where we were up to in 2015
Puccinia triticina (Pt)
Australia New Zealand
104-1,3,4,6,7,9,10,12 +Lr37
104-1,3,4,6,7,8,9,10,12 +Lr37
+Lr28
104-1,3,4,6,7,8,9,10,12 +Lr37

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 Ph
- 1995: Cromey and Viljanen-Rollinson (Virulence of
Puccinia hordei on barley in New Zealand from 1990
to 1993 New Zealand Journal of Crop and
Horticultural Science 23: 115-119) reported a survey
of pathotypic diversity in P. hordei in New Zealand
based on isolates collected between 1990-1993.
- Four pathotypes were reported.
Where we were up to in 2015
Puccinia hordei (Ph)

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 Ph
- 5457 P- and 5457 P+
- Phenotypically similar to pathotypes in Australia but different genotypes.
- The situation in Australia is different with a sexually-recombining population in
South Australia.
What new knowledge do we have in 2016?

12. biosecurity built on science
“Being aware of the nature of these [pathotype] changes allows
pathologists and breeders to examine how other cultivars being
bred or selected for New Zealand might behave. When
pathotypes change or there are new introductions, cultivars that
were previously resistant can be rendered susceptible.”
Rob Craigie, FAR New Zealand
End-User Advocate statement

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 Keep filling in the gaps for the past 15 years.
 Develop stocks of pure isolates to better
understand New Zealand varieties and lines:
- How resistant are they to the different cereal rusts?
- What resistance genes do they contain? Is there a
diverse or narrow range of resistance genes in New
Zealand germplasm?
Future – What are the next steps?

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 For more information, please email
will.cuddy@dpi.nsw.gov.au
 As well as the PBCRC, funding was also provided by: