Rust Resistance Mechanisms - Plant Management Network
Rust Resistance Mechanisms - Plant Management Network
Rust Resistance Mechanisms - Plant Management Network
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<strong>Rust</strong> <strong>Resistance</strong> <strong>Mechanisms</strong>;<br />
Posthaustorial and Prehaustorial<br />
Robert Brueggeman<br />
Barley Pathologist<br />
North Dakota State University
Outline<br />
• Flax rust<br />
• Barley stem rust resistance<br />
• Rpg1<br />
• rpg4/Rpg5<br />
• Conclusions and future<br />
research
Malampsora lini<br />
• model rust pathogen<br />
• Posthaustorial resistace<br />
Puccinia graminis<br />
• wheat stem rust<br />
• three formae speciales<br />
• Many pathogenic races
Flax rust<br />
• Model ‘gene-for-gene’ system<br />
• Molecular data supports a posthaustorial<br />
resistance mechanism
Posthaustorial
Haustorial expressed avirulence<br />
factors
How does the flax model compare<br />
to stem rust resistance in cereals?<br />
• Two cloned barley stem rust resistance genes<br />
• Molecular mechanisms are being elucidated<br />
for both systems<br />
• Different picture materializing for these<br />
resistance mechanisms
Genetic resistance<br />
• A single gene in barley, Rpg1<br />
• Rpg1 deployed in 1942<br />
• Rpg1 has conferred durable resistance
Rpg1 Cloning and Validation<br />
Morex<br />
TMD<br />
Pkinase1<br />
Pkinase2<br />
Rpg1<br />
Golden Promise<br />
Transformant<br />
Brueggeman et al. (2002) PNAS<br />
Horvath et al., (2003) PNAS
Rapid Rpg1 phosphorylation response<br />
specific to avirulent isolates<br />
Nirmala et al. (2010) PNAS
Avirulence spore effector proteins<br />
identified<br />
Nirmala et al. (2011) PNAS
Rpg1 model
Virulence on Rpg1<br />
QCCJ
Route A<br />
Route B<br />
Emergence of Pgt Race TTKSK (Ug99)<br />
Iran<br />
2008<br />
Uganda<br />
1999<br />
Yemen<br />
2007<br />
Pakistan<br />
?<br />
Kenya<br />
2001<br />
Ethiopia<br />
2003<br />
Migration route for race<br />
TTKSK (Ug99)<br />
http://www.ars.usda.gov/Main/docs.htm
pg4 mediated resistance<br />
Barley line Q21861 is the best source of QCCJ resistance<br />
F1 progeny susceptible<br />
F2 segregate 1R:3S<br />
Jin et. al., (1994) Phytopathology
QCCJ and TTKSK resistance mapping<br />
• Q21861 highly resistant to TTKSK<br />
• <strong>Resistance</strong> mapped in Q21861xSm89010<br />
Chr. 5H<br />
DAK133<br />
MWG920.1A<br />
Q21861<br />
Sm89010<br />
ABG705A<br />
ABG395<br />
Ltp1<br />
WG530<br />
ABC324<br />
TTKSK (rpg4)<br />
QCCJ (rpg4)<br />
92-MN-90 (Rpg5)<br />
ABC302A<br />
BCD926<br />
ABG473<br />
MWG514B<br />
WG908<br />
ABG496<br />
rpg4/Rpg5<br />
ABG390<br />
Tel7L<br />
Steffenson et al., (2009) Phytopathology<br />
Borovkova et al., (1995) Phytopathology
pg4/Rpg5 stem rust resistance locus<br />
Brueggeman et al. (2008) PNAS
BSMV-VIGS<br />
Rpg5 VIGS construct<br />
Rpg5<br />
Brueggeman et al. (2008) PNAS
Rpg5 gene<br />
Novel NBS-LRR-STPK structure<br />
BSMV-VIGS<br />
no virus no virus asRpg5 asRpg1 pBluescript<br />
Steptoe<br />
Q21861<br />
Pgs isolate 92-MN-90 (rye stem rust)<br />
Brueggeman et al. (2008) PNAS
pg4 identification
pg4/Rpg5 locus<br />
• genes at Rpg5 locus required for rpg4-mediated<br />
resistance
BSMV-VIGS<br />
VIGS constructs<br />
Pgt race QCCJ inoculation
Two NBS-LRR genes and Adf required
PP2C is putative dominant susceptibility factor
Conclusions<br />
• rpg4-mediated resistance is the interaction of at least<br />
four genes at the rpg4/Rpg5 locus<br />
• Two dominant NBS-LRR containing R-genes are<br />
required for resistance<br />
• Cytoskeleton rearrangement via an actin<br />
depolymerization factor may play a role in resistance<br />
• A PP2C may act as a dominant susceptibility factor
Acknowledgements<br />
NDSU<br />
Barley Pathology<br />
Deepika Arora<br />
Pat Gross<br />
Thomas Gross<br />
Kasia Kinzer<br />
Jon Richards<br />
Prabin Tamang<br />
Xue Wang<br />
Andris Kleinhofs<br />
Brian Steffenson
Questions?
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