[email protected]Effects and interactions of wheat leaf rust adult plant resistance genes in Uruguay P. Silva, V. Calvo-Salazar, F. Condón, M. Quincke, C. Pritsch, L. Gutiérrez, A. Castro, S. Herrera-Foessel, J. von Zitzewitz and S. Germán BGRI Workshop 19-22 August 2013 New Delhi, India
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Effects and Interactions of Wheat Leaf Rust Adult Plant Resistance Genes in Uruguay
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Effects and interactions of wheat leaf rust adult plant resistance genes in Uruguay P. Silva, V. Calvo-Salazar, F. Condón, M. Quincke, C. Pritsch, L. Gutiérrez, A. Castro, S. Herrera-Foessel, J. von Zitzewitz and S. Germán
BGRI Workshop 19-22 August 2013 New Delhi , India
§ Introduction
§ Objective
§ Materials and methods
§ Results and Discussion
§ Conclusions
§ Future works
Outline
INTRODUCTION
URUGUAY
Uruguay - South America (34ºS, 55ºW)
Wheat area Regional: 6 million has
Uruguay: 0.5 million has
54 % of S, MS and I cultivars
DIEA, 2013
Leaf rust: most important and
widespread wheat rust
§ High dynamism of the pathogen population § Short duration of resistance § Cultivar replacement
Genetic resistance is the best strategy to control LR Increase use of slow rusting resistance (durable)
Slow rusting genes
For leaf rust:
§ Lr34/Yr18/Pm38/Sr57/Bs: 7DS
§ Lr46/Yr29/Pm39/Sr58: 1BL
§ Lr67/Yr46: 4BL
§ Lr68: 7BL
For stem rust:
§ Sr2/Yr20/Lr27: 3BS
Pleiotropic effect or linkage
Combinations of 4 - 5 of these genes results in near immunity
Most reported to have differential expression at different temperatures
Environmental effect on LR resistance
Principal component analysis of leaf rust severity of Avocet-S x Parula population in South America and Mexico
Germán et al. 2010
PC1:59.8% PC2:13.0%
Differential expression of resistance genes present in Parula under different environments
Mexico Southern Cone
Environmental effect on LR resistance
0
10
20
30
40
50
60
70
80
LR Cluster 1 LR Cluster 2 LR Cluster 3
% disease severity
none
only Lr46
only LrP
only Lr34
Lr46+LrP
Lr46+Lr34
LrP+Lr34
Lr46+LrP+Lr34
0
10
20
30
40
50
60
70
80
LR Cluster 1 LR Cluster 2 LR Cluster 3
% disease severity
none
only Lr46
only LrP
only Lr34
Lr46+LrP
Lr46+Lr34
LrP+Lr34
Lr46+LrP+Lr34
No
gene
s Lr
46
Lr68
Lr
34 Lr46
+Lr6
8 Lr
46+L
r34
Lr68
+Lr3
4 Lr
46+L
r68+
Lr34
MEXICO 1997, 1998
§ Lr46, Lr68: moderate effect
§ Lr34: most effective
Modified from Lillemo et al. 2011
0
10
20
30
40
50
60
70
80
LR Cluster 1 LR Cluster 2 LR Cluster 3
% disease severity
none
only Lr46
only LrP
only Lr34
Lr46+LrP
Lr46+Lr34
LrP+Lr34
Lr46+LrP+Lr34N
o ge
nes
Lr46
Lr
68
Lr34
Lr
46+L
r68
Lr46
+Lr3
4 Lr
68+L
r34
Lr46
+Lr6
8+Lr
34
URUGUAY 2005 to 2007 ARGENTINA 2007
0
10
20
30
40
50
60
70
80
LR Cluster 1 LR Cluster 2 LR Cluster 3
% disease severity
none
only Lr46
only LrP
only Lr34
Lr46+LrP
Lr46+Lr34
LrP+Lr34
Lr46+LrP+Lr34
§ Lr46: no effect
§ Lr68: most effective
§ Lr34: moderate effect
The expression of the slow rusting genes vary under different environments
Environmental effect on LR resistance
Which are the genes and specific gene combinations that are most appropriate to reduce LR in different target environments
Objective
Investigate the presence, relative effects and interactions of durable resistance genes present in Parula on leaf rust severity by using linked molecular markers in two BC1F6 populations in Uruguay
MATERIALS AND METHODS
LE2304*2/Parula: 73 BC1F6 lines – Population 1 ORL99102*2/Parula: 69 BC1F6 lines – Population 2
Resistant donor:
Parula - México (CIMMYT)
Adapted - previously described as susceptible to LR - presence of slow rusting genes: unknown
LE2304 – Uruguay (INIA)
ORL99192 – Brazil (OR-Sementes)
Lr34, Lr46, Lr68 and Sr2 ( Singh et al., 2011; Herrera-Foessel et al., 2012)