1986
1986
1991
1991 1992/3 1993/4
1997/8
1995/6
1994/5
1983
1985
2nd International Wheat Stipe Rust Symposium
Izmir, Turke...
 Trace to 100% yield losses depending on the
time of the epidemic initiation, susceptibility
of variety & climatic condit...
The good news:
 More productive spring, facultative and winter
wheat germplasm, resistant to current yellow
rust (and oth...
Immediate action points:
 Reduce the area sown to susceptible varieties
by promoting new varieties with diverse
resistanc...
Long-term R4D for a sustainable
yellow rust control (1)
 Surveillance of pathogen population for a timely detection
of ne...
Long-term R4D for a sustainable
yellow rust control (2)
 Identification of new resistance genes and their utilization
 R...
Reality with the utilization of
large effect race-specific genes
● Most often end up being used as a single gene –
steward...
Breeding minor, slow-rusting genes based adult plant
resistance in combination with small/intermediate effect race-
specif...
Pleiotropic multi-pathogen resistance:
a subclass of adult plant resistance genes
● Lr34 [ Syn. = Yr18=Sr57=Pm38 =Ltn1=Sb1...
Start0.0
Xgwm49769.7
XksuH9c70.4
XksuG34b72.5
End131.4
start0.0
Xwmc1474.8
Centromere99.5
End204.0
Xgwm2106.4
Xbarc12414.9...
Examples of small/moderate effect race-specific
resistance genes characterized recently at CIMMYT and
their interaction wi...
APR QTL interaction in enhancing yellow rust
resistance of Avocet x Quaiu3 RILs
Yr29 Yr30
Yr54
Minor
QTL
Yr29+
Yr30+
3D QT...
Moderately effective race-specific gene YrF on 2BS and slow rusting genes
together confer a high level of YR resistance in...
Race-specific gene YrSuj on 7BL and slow rusting APR genes together
confer a high level of resistance in Avocet/Sujata map...
Future: GM intervention to achieve resistance durability
Gene Cassettes- multiple resistance genes inherited as a single u...
Conclusions
 Sustainable yellow rust control will require growing resistant
varieties in disease prone areas around the w...
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2014 braun singh et al izmir april 28

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2014 braun singh et al izmir april 28

  1. 1. 1986 1986 1991 1991 1992/3 1993/4 1997/8 1995/6 1994/5 1983 1985 2nd International Wheat Stipe Rust Symposium Izmir, Turkey, May 2014 H-J Braun, RP Singh, J Huerta-Espino, SA Herrera-Foessel, C Lan & BR Basnet Global status of yellow rust on wheat and strategies for its short and long term control
  2. 2.  Trace to 100% yield losses depending on the time of the epidemic initiation, susceptibility of variety & climatic conditions  Selection of virulence for resistance genes Yr9 and Yr27 associated with epidemics in the last 25 years in Africa, Middle East and Asia  Worldwide spread of aggressive, temperature tolerant races and their further evolution:  new areas, initiation of epidemics at earlier growth stages and higher severity  Fungicide application becoming a routine in some countries Global status of yellow rust
  3. 3. The good news:  More productive spring, facultative and winter wheat germplasm, resistant to current yellow rust (and other rusts) populations has been distributed through various international yield trials and nurseries, and also developed by various National Programs during past years  Various yellow rust resistant varieties released in different countries
  4. 4. Immediate action points:  Reduce the area sown to susceptible varieties by promoting new varieties with diverse resistance  Release and seed multiplication of resistant varieties in countries lagging behind  Release and promotion of additional varieties with complex resistance base If not done then in 3rd YR conference we will assemble & discuss the same again
  5. 5. Long-term R4D for a sustainable yellow rust control (1)  Surveillance of pathogen population for a timely detection of new virulences of relevance  Trap nurseries (NILs and varieties)  Race characterization (GRC-Denmark, Turkey/ICARDA in Izmir, India, Pakistan, Iran, China, Mexico, USA, Australia, etc.)  Information on the resistance genes present in commercial varieties and important breeding materials  Gene postulation, molecular mapping- robust diagnostic markers  High-throughput markers assays
  6. 6. Long-term R4D for a sustainable yellow rust control (2)  Identification of new resistance genes and their utilization  Race-specific genes- large & small effect; seedling & adult-plant  Slow rusting, pleiotropic adult-plant resistance genes  Breeding more productive wheat varieties  Utilizing race-specific effective resistance genes in combinations (preferably 3 genes per combination)  Strong molecular breeding approaches for a forward breeding  Utilizing multiple minor, slow rusting genes, or their combination with small/intermediate effect race-specific genes  Field based selection in conjunction with other traits  Fungicides are part of the solution
  7. 7. Reality with the utilization of large effect race-specific genes ● Most often end up being used as a single gene – stewardship / stacking ● Molecular breeding being practiced only in some programs but often results in non-competitive varieties ● Few effective genes with reliable molecular markers available at present ● Stronger emphasis required for marker assisted pyramiding of genes together with forward breeding approaches including genomic selection
  8. 8. Breeding minor, slow-rusting genes based adult plant resistance in combination with small/intermediate effect race- specific resistance genes for achieving near-immune resistance from seedling growth stages ● Resistance based on 4-5 slow rusting APR genes is usually adequate in areas where yellow rust infection initiates from stem elongation stages onwards (APR genes are already functioning by then) ● However, with the aggressive races of yellow rust- infection in some areas initiates as early as tillering stage when APR genes still not fully functional ● Utilize combinations of slow rusting APR genes with small/intermediate effect race-specific resistance genes that have enhanced expression due to additive effects
  9. 9. Pleiotropic multi-pathogen resistance: a subclass of adult plant resistance genes ● Lr34 [ Syn. = Yr18=Sr57=Pm38 =Ltn1=Sb1= Bdv1] chromosome 7DS (leaf rust, yellow rust, stem rust, powdery mildew, leaf tip necrosis, spot blotch, barley yellow dwarf virus ) ● Lr46 [ Syn.= Yr29=Sr58=Pm39=Ltn2=Ts?] chromosome 1BL ● Lr67 [Syn.= Yr46=Sr55=Pm46=Ltn3] chromosome 4DL Formation of cell wall appositions (instead of hypersensitivity with race-specific genes)
  10. 10. Start0.0 Xgwm49769.7 XksuH9c70.4 XksuG34b72.5 End131.4 start0.0 Xwmc1474.8 Centromere99.5 End204.0 Xgwm2106.4 Xbarc12414.9 Xwmc154a28.5 Xgwm148b61.2 Xbarc1884.5 Xwg99687.0 Xglk40087.8 Xbarc13b88.8 Centromere95.6 Xwmc245b98.1 Xpsr92499.7 Xbarc124a101.3 Xbarc230103.6 Xbarc167105.0 Xgwm120112.7 Xpsr540117.0 XwPt-6278121.9 Xwmc175b126.5 Xwmc332134.2 End172.2 Start Xwmc1110.0 Xgwm2619.1 Xcfd5310.0 Centromere22.0 Xgwm10229.2 Xwmc19043.9 XwPt-372852.2 Xgwm53953.9 Xgwm34983.6 Xgwm30192.0 Xgwm320 End95.0 Start0.0 Xcfd3630.3 Xgwm359b52.2 Xgwm122a56.3 Centromere88.4 Xcfa2263102.7 Xsfr.BE590525a133.1 Xwmc170152.1 End213.5 Start0.0 XwPt-78902.9 Xbarc31023.0 Centromere49.3 Xpsr59854.0 Xpsr57058.4 Xpsr54360.9 End170.1 Start0.0 Xfba9189.4 Xfba24190.0 Xbcd1532104.1 XksuA6109.3 Xbarc125121.4 Xgwm456133.1 Centromere156.4 End226.6 Start0.0 Centromere29.2 gwm742 gwm83288.2 gwm16088.9 End103.2 Start0.0 Centromere9.0 gwm54010.1 wmc23811.9 gwm49517.0 gwm16519.9 gwm36822.1 gwm14923.0 End70.7 Start0.0 glk42459.1 Centromere60.9 barc15185.3 Vrn197.2 Xfbb209.1105.0 Xabg391110.0 gwm126117.7 End133.5 Start0.0 Centromere34.5 gwm63955.3 wmc415a56.8 gwm49959.6 End158.5 Start gwm4590.0 gwm3343.8 wPt-095942.5 Centromere45.7 wPt-706358.8 wmc256b69.9 barc377.4 gwm617107.7 gwm427111.2 End112.0 Start0.0 Centromere75.0 bcd1510120.4 ksuD27134.8 End149.5 Start Xgwm470.0 wPt-8149 wP7.0 gwm66618.2 fba12751.8 Xwmc28375.7 barc17485.5 cfa217491.2 Xbarc10899.9 Centromere104.1 End207.0 Start0.0 gwm935c57.0 gwm57357.9 gwm4661.6 gwm4367.5 Centromere69.0 psr35086.8 psr129a88.3 pwir23297.4 psr59398.1 gwm131103.0 wmc273a106.4 ksuD2116.3 gwm146a119.8 gwm146b133.0 wmc273b134.4 psr680b136.9 gwm344b142.8 barc182143.5 gwm577156.6 End190.7 Chromosome 1A Chromosome 7DChromosome 6DChromosome 5DChromosome 4DChromosome 3D Chromosome 7BChromosome 6BChromosome 5BChromosome 4BChromosome 3BChromosome 2B Chromosome 7AChromosome 6AChromosome 5AChromosome 4AChromosome 3A Chromosome 2D Chromosome 2A Chromosome 1D Chromosome 1B Start0.0 Xpsr94943.0 Centromere45.1 Xgwm60454.4 Xgwm18a55.3 Xgwm1160.8 Xgwm27361.7 glk48363.2 Xgwm13168.5 Xgwm268117.4 Xwmc44159.5 Xgwm793173.0 Lr46/Yr29/ Sr58/Pm39 Start0.0 Xcfd6626.9 XwPt-332841.7 Xgwm29552.2 Xgwm13055.0 XcsLV3456.4 Xbcd143859.1 Xgwm1002a59.5 Xwmc405b79.2 Xgwm1002b80.3 Centromere97.9 End227.0 Start0.0 gwm13233.0 Centromere48.0 barc10155.0 barc13656.8 gwm19361.0 gwm36163.0 gwm62676.6 gwm21992.7 End104.5 Start0.0 Centromere23.4 End268.0 Start0.0 gwm16530.0 Centromere30.5 gwm19231.3 End84.1 Lr67/Yr46/ Sr55/Pm46 Lr34/Yr18/ Sr57/Pm38 Start0.0 Xgwm389a2.4 Xgwm533a7.6 Xgwm493a20.0 Xpsr91991.5 Xpsr110195.5 Xgwm383a150.8 Xgwm131b179.7 XwPt-0036198.4 Xbcd131212.6 Xgwm299c270.4 Xgwm340301.1 End306.4 Sr2/Yr30 Diversity for Yellow Rust QTL (marked in yellow): > 35 regions through consensus maps (Rosewarne et al. TAG 2013, 126:2427-2449 )
  11. 11. Examples of small/moderate effect race-specific resistance genes characterized recently at CIMMYT and their interaction with slow rusting genes ● Yr54 in Quaiu3 on 2DL ● YrF in Francolin on 2BS ● YrSuj in tall variety Sujata on 7BL ● Yr60 in Lalbahadur on 4AL Contrasting example: A race-specific gene with minor effect in seedlings but immunity in adult plants: ● YrKK in tall variety Kenya Kudu on 2BS
  12. 12. APR QTL interaction in enhancing yellow rust resistance of Avocet x Quaiu3 RILs Yr29 Yr30 Yr54 Minor QTL Yr29+ Yr30+ 3D QTL Yr29+ Yr30+ 3D QTL+ Yr54 Source: Basnet et al. Plant Dis. 2013
  13. 13. Moderately effective race-specific gene YrF on 2BS and slow rusting genes together confer a high level of YR resistance in Francolin#1 Other APR genes/QTL • Lr46/Yr29 on 1BL • Yr30/Sr2 on 3BS • Two additional minor QTL PVE: 10.3–21.1% Source: Lan et al. (2014) Mol. Breed. DOI 10.1007/s11032-014-0075-6 Francolin#1 is an improved CIMMYT semidwarf & shows high level of resistance to yellow rust- 50% severity when YrF present alone
  14. 14. Race-specific gene YrSuj on 7BL and slow rusting APR genes together confer a high level of resistance in Avocet/Sujata mapping population Other APR genes/QTL Lr46/Yr29 (PVE:5.6-6.2%) Lr67/Yr46 (PVE: 6.9-10.7%) QYrLr.cim-7BL (PVE: 11.7-20.9%) QYr.cim-1AS (PVE: 5.7-8.9%) QYr.cim-3DS (PVE: 6.3-8.2%) Sujata is an improved tall variety from India & shows high level of resistance to yellow rust- 40% severity when YrSuj present alone Source: Lan et al. (unpublished)
  15. 15. Future: GM intervention to achieve resistance durability Gene Cassettes- multiple resistance genes inherited as a single unit: simplifying breeding and enhancing resistance durability Lr34/Yr18 Yr36 Lr21 SynR1 SynR2 SynR3 Natural gene cassette (currently developed) Synthetic gene cassette (future possibility)  Natural gene cassettes currently in the pipeline at CSIRO Lr34/Yr18/Sr57 +Lr67/Yr46/Sr55 +Lr21 +Yr36 • Cloning many resistance genes for diversity • Technology for insertion of large DNA “packages” – gene expression • Synthetic R genes? • Cisgenic vs Transgenic crops Scientific/Commercialisation Challenges Source: CSIRO-GRDC Triple Rust Initiative
  16. 16. Conclusions  Sustainable yellow rust control will require growing resistant varieties in disease prone areas around the world  Wheat varieties should be enriched with multiple pleiotropic APR genes, representing a novel class of resistance to rusts and other wheat pathogens, to curtail/slow down pathogen evolution  Although near-immune level of durable resistance to all three rusts can be achieved through field selection, molecular markers can aid better utilization & diversity  New approaches, such as “resistance gene cassettes” could further expedite breeding for durable rust resistance  Fungicides should be part of the rust control strategy

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