Historical Overview of Stripe Rust Research
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Transcript of Historical Overview of Stripe Rust Research
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ROBERT A. MCINTOSHTHE UNIVERSITY OF SYDNEY PLANT BREEDING INSTITUTE
COBBITTY, NSWAUSTRALIA
Historical Overview of Stripe Rust Research
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TAXONOMY OF THE PATHOGEN
Reviewed and revised by Liu & Hambleton (2010)
- Uredo glumarum Schmidt - before 1819
- P. glumarum Eriks. & Henn. 1894 (until the 1950s)
- Puccinia striaeformis Westend. 1954
- P. striiformis
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SPECIES SPECIALIZATION
Liu & Hambleton (2010) using its & beta-tubulins
-P. striiformis on the triticeae
-P. gansensus on achnatherum inebrians
P. striformoides on Dactylis glomerata
P. pseudostriiformis on Poa. spp.
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f. sp. tritici
f. sp. hordei
f. sp. pseudohordei - PNW21?
Puccinia striiformisformae speciales
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Almost worldwideHistorically considered to favour cooler areasRecent outbreaks defy assumptionsAre there unique aspects of environment that determine distribution?Are current races more adapted to high temperaturesWhat factors determine distribution within regions?
Puccinia striiformis tritici
Distribution
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Up to 50%, but occasionally higher
Stripe rust losses
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DISEASE CYCLEEpidemic Phase – during the cropping
cycleSurvival Phase – during the non-cropping
season
The rust pathogens are obligate parasites and need living plants to survive in the uredinial stages
During non-optimal periods one generation of the fungus may take longer than 1-2 weeks
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LIFE CYCLE OF A RUST PATHOGEN
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EPIDEMIOLOGY
- Role of the sexual hosts- What species of barberry?- Where?- Are they important in relation to Pst on wheat?
- Role of asexual hosts- What grass species?- Where?- Are they important in rust survival?
VOLUNTEER WHEAT IS PROBABLY THE MAIN SOURCE OF INOCULUM
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PATHOGENIC VARIATION IN PST
Differential sets for seedling assaysWhy Have differential sets?Genetics of the differentialsRepeatability of dataNaming races
German, European, North American, Indian, Chinese
Environmental conditions for testing Differentials for field assays???
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GENETICS OF RESISTANCE
Seedling resistances We still do not know the genetic bases of
resistance in differentials Problems in international race variation
Adult plant resistancesRecognized from the 1960s - Zadoks, Stubbs, Sharp, Bingham, Law
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DURABILITY OF RESISTANCE
Resistances/resistance genes effective at the seedling stage have not proven to be durable. There are many genes of this type
At least some resistances/resistance sources for APR have proven durable. There are many genes of this type
BUT not all gene/gene sources for APR are durable
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BREEDING FOR STRIPE RUST RESISTANCE
There is no shortage of resistanceResistance must be in the best varietiesWe must have rust to select for
resistance (even when we have markers!!)
Value of international testingProblems of lack genetic diversity
Megavarieties Copycat breeding
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POST-RELEASE VARIETY MANAGEMENT
Avoid/Remove/Prevent/Discourage highly susceptible varieties – the bushfire effect!!Need to monitor pathogen populations over space and time – using differentials or markers
Need to monitor relative disease responses in relation to variety make-up, changing agronomic practices, climate change,
neighbours. Rust is a social issue At the international level need to build up
a co-operative attitude to information sharing, mutual sharing of risk analysis, and trust
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WHAT MAKES RUST EXCITING