sources of stem rust resistance in cultivated and wild tetraploids

Sources of Stem Rust Resistance in Cultivated and Wild Tetraploids

Pablo D. Olivera and Yue Jin

University of Minnesota USDA-ARS Cereal Disease Laboratory

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

2

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

3

Njoro Nursery

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

4

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

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

6

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

7

● 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

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)

8

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

9

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

10

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%)

11

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

# en

trie

s

Infection Response

Origins of Resistant Durum Entries

13

Egypt, 27

Mexico, 50

Ethiopia, 44

USA, 32

Canada, 9

Others, 65

Turkey, 8

Italy, 8

Chile, 10

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

14

Infection Types at Seedling Stage

Emmer

(T. turgidum ssp. dicoccoum)

Durum wheat

(T. turgidum ssp. durum)

15

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

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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Infection Types at Seedling Stage

Wild emmer wheat

(T. turgidum ssp. dicoccoides)

Persian wheat

(T. turgidum ssp. carthlicum)

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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

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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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



Wild emmer PI 428116 1 part. dominant 2 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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90K SNP Chip

Line Line Type Origin

Durum PI 298547 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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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)

23

Infection Types in Aegilops

Ae. biuncialis

Ae. cylindrica

Ae. neglecta

Ae. triuncialis

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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

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

26

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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sources of stem rust resistance in cultivated and wild tetraploids

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