Pablo Olivera, University of Minnesota

1. Sources of Stem Rust Resistance in
Cultivated and Wild Tetraploids
Pablo D. Olivera and Yue Jin
University of Minnesota
USDA-ARS Cereal Disease Laboratory

2. Contents
• Introduction
- Pgt races at Debre Zeit durum nursery
• Resistance to stem rust in tetraploid wheats
- durum and cultivated emmer
- wild emmer and other cultivated tetraploids
- genetics of resistance and mapping
• Resistance to stem rust in Aegilops ssp.
• Summary
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3. Stem Rust Resistance in Durum
● Durum wheat of North America has a higher frequency of resistance to
TTKSK (Ug99) than common wheat
● We postulated that resistance to TTKSK in durum is most likely due to
Sr13
● When durum resistant selections were
evaluated in Debre Zeit (Ethiopia), many
became susceptible to stem rust
● Hypothesis: stem rust races in Debre Zeit
may possess a virulence combination
that overcome the TTKSK resistance
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Njoro Nursery

4. Durum Stem Rust Field Nursery
• Debre Zeit, Ethiopia
• Located in a major durum wheat
growing area
• Two growing seasons
Main season: July – October
Off season: February - May
Debre Zeit
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5. Races Identified at Debre Zeit Nursery
TRTTF
Virulent on Sr13 and Sr9e
Virulent on Sr36 and SrTmp
Avirulent on Sr31 and Sr24
JRCQC
Virulent on Sr13 and Sr9e
Avirulent on Sr36 and SrTmp
Avirulent on Sr31 and Sr24
JRCQC TRTTF TTKSK JRCQC TRTTF TTKSK
Sr13 Sr9e
Olivera et al., 2012. Plant Disease 96: 623-628 5

6. Tetraploids as a Source of Resistance Genes
Gene Donor Relevance
Sr2 Emmer Adult Plant Resistance
Sr13 Emmer
Main component of SR resistance in NA durum
Effective against Ug99
Sr9e Emmer
Main component of SR resistance in NA durum
Ineffective against Ug99
Sr14, 17, 9d Emmer
Sr12 Durum May play a role in Ug99 resistance in bread wheat
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7. Genetic Resources
● The USDA – ARS National Small Grains Collection (NSGC) has an
extensive collection of tetraploid wheats (Triticum turgidum ssp.)
~ 8300 durum
~ 2100 cultivated and wild tetraploids
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● Objectives:
1. Identify and characterize new sources of stem rust resistance in
the T. turgidum collection deposited at NSGC
2. Elucidate the genetics of resistance and mapping of resistance
genes

8. Tetraploids Evaluated
Name Species Number Evaluations
Durum T. turgidum ssp. durum 5,000 Adult - seedling
Emmer T. turgidum ssp. dicoccum 359 Adult - seedling
Wild emmer T. turgidum ssp. dicoccoides 880 Seedling
Persian wheat T. turgidum ssp. carthlicum 77 Seedling
Polish wheat T. turgidum ssp. polonicum 63 Seedling
Oriental wheat T. turgidum ssp. turanicum 66 Seedling
Poulard wheat T. turgidum ssp. turgidum 414 Seedling
TOTAL 6,859
Accessions deposited at the NSGC (Aberdeen, ID)
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9. Durum and Emmer - Phenotypic Evaluation
Entries resistant to moderately resistant in Debre Zeit are evaluated in:
Debre Zeit and St. Paul, MN in two growing seasons
All entries evaluated in Debre Zeit (Ethiopia) stem rust nursery
Entries resistant to moderately resistant in all field evaluations are evaluated at
seedling stage against races:
TTKSK (Kenya), TRTTF (Yemen), TTTTF (USA)
Accessions resistant to race TTKSK are evaluated against:
JRCQC, TKTT- (Ethiopia)
TPMKC, RKQQC, RCRSC, QTHJC, QFCSC, MCCFC (USA)
Durum
5,000 entries
modern and old cultivars, breeding lines, landraces
Emmer
359 entries
Ethiopia, Europe, Caucasus, and Middle East
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10. Stem Rust Field Nurseries
Debre Zeit
Inoculum 2009 - 2010:
TTKSK + bulk of Ethiopian isolates
(50:50)
Inoculum 2011 - 2013:
100% bulk of Ethiopian isolates
St. Paul
Inoculum 2009 - 2013:
TPMKC, RKQQC, RCRSC, QTHJC,
QFCSC, MCCFC
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11. Field Evaluation
Durum Emmer
# entries evaluated in Debre Zeit nursery 5,000 359
# (%) of entries resistant to moderately resistant 914 (18.3%) 164 (50.3%)
# (%) entries R to MR in all Debre Zeit evaluations 298 (6.0%) 51 (14.2%)
# (%) of entries R to MR in all field evaluations 252 (5.0%) 39 (10.8%)
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12. Distribution of Resistant Entries
12
0
10
20
30
40
50
60
70
R R-MR MR-R MR MR-MS MS-MR MS
Debre Zeit
St. Paul
#entries
Infection Response

13. Origins of Resistant Durum Entries
13
Egypt, 27
Mexico, 50
Ethiopia, 44
USA, 32
Canada, 9
Others, 65
Turkey, 8
Italy, 8
Chile, 10

14. Seedling Evaluation
Durum Emmer
# accessions resistant in all field evaluations 252 39
# accessions resistant to race TTKSK at seedling 240 32
# accessions resistant to all races 133 28
# accessions susceptible against all races 9 4
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15. Infection Types at Seedling Stage
Emmer
(T. turgidum ssp. dicoccoum)
Durum wheat
(T. turgidum ssp. durum)
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16. Wild Emmer and Other Cultivated Tetraploids
University of Minnesota - BSL3 facility
All the accessions evaluated at SEEDLING STAGE against:
TTKSK (Kenya), TRTTF (Yemen), TTTTF (USA)
Accessions resistant to race TTKSK are evaluated against:
JRCQC, TKTT- (Ethiopia)
US races: TPMKC, RKQQC, RCRSC, QTHJC, QFCSC, MCCFC
Location: Biosecurity Level 3 facility
University of Minnesota
Period: December 1st – March 31st

17. Seedling Evaluation
# of
access.
Accessions Resistant to
Species TTKSK TRTTF TTTTF 3 Races 10 Races
Wild emmer 880 152 178 123 32 11
Persian wheat 77 33 12 19 15 12
Polish wheat 66 15 14 13 11 10
Oriental wheat 66 6 1 0 0 0
Poulard wheat 414 44 114 146 43 42
TOTAL 1503
250
(16.3%)
319
(21.2%)
301
(20.0%)
101
(6.7%)
75
(5.0%)
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18. Infection Types at Seedling Stage
Wild emmer wheat
(T. turgidum ssp. dicoccoides)
Persian wheat
(T. turgidum ssp. carthlicum)
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19. Genetics of Resistance and Mapping
45 biparental crosses
27 durum, 5 emmer, 6 wild emmer, 2 Persian, 2 Polish, 3 Poulard
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F3 generation
Phenotypic evaluation at seedling (TTKSK TRTTF)
Bulk Segregant Analysis
90K SNP platform
Identify chromosomal region of interest
Genotype F2 population with SNPs markers
Resistant in all seedling evaluations
F6 generation
Field evaluation in Ethiopia and St. Paul
QTL mapping
90K SNP platform
Susceptible in all seedling evaluations
Markers to confirm presence/absence of Sr2

20. Crosses – Durum (F3 generation)
Line Type Origin
Resistant genes
TTKSK TRTTF
CItr 13338 Breed. line Canada 3 recessive 2 dominant
PI 520569 Breed. line Chile 1 dominant 3 dominant
CItr 17337 Cultivar Canada 1 dominant 1 dominant
PI 428549 Cultivar France 1 dominant 2 dominant
PI 506469 Cultivar Colorado (USA) 1 dominant 3 dominant
PI 191645 Old cultivar Brazil 1 dominant 1 dominant
PI 298547 Landrace Ethiopia 2 dominant 2 dominant
PI 479923 Landrace Ethiopia 2 recessive 2 recessive
PI 479959 Landrace Ethiopia 1 dominant 1 dominant
PI 519559 Landrace Syria 1 dominant 1 dominant
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21. Crosses – Other Tetraploids
Species Resistant Line TTKSK TRTTF TTTTF
Emmer PI 101971 1 part. dominant 1 part. dominant 2 dominant
Emmer PI 193883 1 recessive 1 recessive 1 dominant + 1 recessive
Emmer PI 217640 1 part. dominant 1 part. dominant 1 dominant + 1 recessive
Emmer PI 298582 1 recessive 1 recessive 1 dominant + 1 recessive
Emmer PI 319869 1 recessive 1 recessive 1 dominant + 1 recessive
Wild emmer PI 428116 1 part. dominant 2 part. dominant
Wild emmer PI 466946 2 part. dominant 2 part. dominant
Wild emmer PI 466960 2 part. dominant 2 part. dominant
Wild emmer PI 466979 1 part. dominant 1 part. dominant
Wild emmer PI 471652 1 part. dominant 1 part. dominant
Wild emmer PI 471766 2 recessive 1 part. dominant
Persian PI 168672 1 dominant 1 dominant
Persian PI 387696 2 dominant 1 dominant
Polish PI 384339 1 dominant 1 dominant
Poulard CItr 7772 1 recessive 1 dominant
Poulard CItr 7840 1 recessive 2 dominant
Poulard PI 387336 1 recessive 1 dominant
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22. 90K SNP Chip
Line Line Type Origin
Durum PI 298547 Landrace Ethiopia
Durum PI 479923 Landrace Ethiopia
Durum PI 479959 Landrace Ethiopia
Durum PI 519559 Landrace Syria
Durum PI 191645 Old cultivar Brazil
Durum PI 506469 Cultivar USA
Durum PI 428549 Cultivar France
Emmer PI 217640 Cultivated India
Wild emmer PI 466960 Wild Israel
Wild emmer PI 466946 Wild Syria
Poulard PI 387336 Cultivated Ethiopia
Parents F1
PI 134946 x PI 387336
Parents F1
Citr 7966 x PI 217640
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23. Aegilops
Species Genome
# of
accessions
Seedling evaluation
TTKSK TRTTF TTTTF 3 Races
Ae. cylindrica DDCC 151 133 1 102 1
Ae. geniculata MMUU 183 145 159 156 136
Ae. triuncialis UUCC 353 290 198 315 166
Ae. biuncialis UUMM 262 75 179 82 34
Ae. neglecta UUMM 202 189 183 170 158
Ae. peregrina SSUU 73 64 47 24 14
TOTAL 1224
896
(73.2%)
767
(62.7%)
849
(69.3%)
509
(41.6%)
Accessions deposited at the NSGC (Aberdeen, ID)
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24. Infection Types in Aegilops
Ae. biuncialis
Ae. cylindrica
Ae. neglecta
Ae. triuncialis
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25. Genetics of Resistance and Mapping
● 25 intraspecific crosses were performed in the six Aegilops species
● Objectives:
1. to elucidate the genetics of stem rust resistance in Aegilops spp.
2. to develop genetic linkage maps for each species and map stem
rust resistance genes
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Species Accession Origin Infection Type Gene/s
Ae. peregrina PI 604185 South Israel 2 1 part. dominant
Ae. peregrina PI 604193 North Israel ; 1 dominant
Ae. triuncialis PI 254861 Iraq 2- 2 dominant
Ae. triuncialis PI 221899 Afghanistan 22- 2 dominant
Ae. triuncialis PI 374357 Serbia ; 1 dominant

26. Summary
● Races identified in Ethiopia are virulent on genes effective
against Ug99 (Sr13, Sr36, Tmp), and genes widely used in
durum breeding programs (Sr13, Sr9e)
● Cultivated and wild tetraploids are a good source of resistance
genes and could be used in wheat improvement for stem rust
resistance
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27. Acknowledgements
● USDA-ARS, Cereal Disease Laboratory stem rust group
● Scientists and Staff at EIAR, Ethiopia (Debre Zeit R.C.)
● H. Bockelman, USDA-ARS National Small Grains Collection
● S. Chao, USDA-ARS Red River Valley Agricultural Research Center
● Durable Rust Resistance of Wheat (DRRW), Cornell University
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