Mapping of durable adult plant stem rust resistance to Ug99 and its races<br />S. Bhavani, R. P. Singh, S. Singh, J. Huert...
Ug99-Global threat<br /><ul><li>Wide virulence range and highly aggressive
Threat to significant proportion of global wheat germplasm > 80% susceptible
New races in Ug99 (TTKSK) lineage</li></ul>Ug99+Sr24 Virulence (2006)-TTKST<br />Ug99+Sr36 Virulence (2007)-TTTSK<br />Oth...
Types of Resistance<br />≈ Race-specific <br />≈ Major  genes <br />≈ Hypersensitive<br />Monogenic<br />(Boom & Bust)<br ...
Focus towards durable resistance?<br /><ul><li>Multiple races of rust pathogens
Mutating and migrating nature of rust pathogens
Several race-specific genes ineffective in one or</li></ul>more wheat growing regions<br /><ul><li>Maintaining host geneti...
Preventing epidemics – reducing yield losses</li></li></ul><li>Characteristics of slow rusting resistance <br />Minor gene...
Lower disease severity, Increased latent period
Small to large compatible pustules on stems
Reduced spore production</li></li></ul><li>Accumulating minor genes - Near immunity <br />% Rust<br />Susceptible <br />10...
Sr2-Complex for durable APR<br />(Sr2  + other minor genes for durable resistance to stem rust)<br /><ul><li>Sr2 transferr...
Sr2  still provides moderate levels of resistance in Kenya (~30% reduction in disease severity)
Seedling and APR  genes with intermediate effects in combination with Sr2 produce enhanced levels of resistance
Formed the basis of durable resistance historically in some CIMMYT wheats</li></li></ul><li>Pyramiding-APR+ Major genes<br...
 Identifying materials with adult plant resistance to Ug99<br />Kingbird<br />Greenhouse seedling tests -USDA-ARS Lab. in ...
Mapping of Adult Plant Resistance to Stem Rust<br /><ul><li>15 RIL mapping populations developed and phenotyped in Kenya f...
Genetic studies suggest the involvement of 3 or 4 minor genes in each resistant parent
Initial molecular mapping of six populations completed
Other populations being assigned to graduate students </li></li></ul><li>Methodology<br /><ul><li>Phenotyping conducted in...
Artificial epidemics with Ug99+Sr24 (TTKST)
SR severity recorded when 80-100% disease on most susceptible RILs- Modified Cobb scale</li></li></ul><li><ul><li>DArT  an...
Inclusive Composite Interval Mapping (ICIM), Q-gene, QTL Cartographer
ICIM- http://www.isbreeding.net/
Increased power of detection
Additive and Epistatic Effects
LOD Scores>2.5, Probability in step wise regression 0.001
Upcoming SlideShare
Loading in …5
×

Mapping of durable adult plant stem rust resistance to Ug99 and its races

2,033 views

Published on

Sridhar Bhavani, CIMMYT

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
2,033
On SlideShare
0
From Embeds
0
Number of Embeds
131
Actions
Shares
0
Downloads
71
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Mapping of durable adult plant stem rust resistance to Ug99 and its races

  1. 1. Mapping of durable adult plant stem rust resistance to Ug99 and its races<br />S. Bhavani, R. P. Singh, S. Singh, J. Huerta, O. Argillier, S. Brun, S. Lacam, N. Desmouceaux, P. Njau and R. Wanyera<br />
  2. 2. Ug99-Global threat<br /><ul><li>Wide virulence range and highly aggressive
  3. 3. Threat to significant proportion of global wheat germplasm > 80% susceptible
  4. 4. New races in Ug99 (TTKSK) lineage</li></ul>Ug99+Sr24 Virulence (2006)-TTKST<br />Ug99+Sr36 Virulence (2007)-TTTSK<br />Other races-TTKSF,TTKSP, PTKSK,<br />PTKST<br />Virulence spectrum of Ug99 (TTKSK)<br />
  5. 5. Types of Resistance<br />≈ Race-specific <br />≈ Major genes <br />≈ Hypersensitive<br />Monogenic<br />(Boom & Bust)<br /> Pyramiding<br />≈ Race-nonspecific <br />≈ Minor genes <br />≈ Slow rusting/ Partial<br />Polygenic<br />(Durable)<br />
  6. 6. Focus towards durable resistance?<br /><ul><li>Multiple races of rust pathogens
  7. 7. Mutating and migrating nature of rust pathogens
  8. 8. Several race-specific genes ineffective in one or</li></ul>more wheat growing regions<br /><ul><li>Maintaining host genetic diversity
  9. 9. Preventing epidemics – reducing yield losses</li></li></ul><li>Characteristics of slow rusting resistance <br />Minor genes with small to intermediate effects<br />Gene effects are usually additive<br />Resistance does not involve hypersensitivity<br />Susceptibility at seedling stage<br />Genes confer slow disease progress through:<br /><ul><li>Reduced infection frequency- Receptivity
  10. 10. Lower disease severity, Increased latent period
  11. 11. Small to large compatible pustules on stems
  12. 12. Reduced spore production</li></li></ul><li>Accumulating minor genes - Near immunity <br />% Rust<br />Susceptible <br />100<br />80<br />1 to 2 minor genes <br />60<br />2 to 3 minor genes<br />Munal, Picaflor,<br />Francolin, Pauraque<br />40<br />20<br />4 to 5 minor genes<br />Kingbird<br />0<br />20<br />0<br />10<br />30<br />50<br />40<br />Days data recorded<br />Relatively few additive genes, each having small to intermediate effects, required for satisfactory disease control<br />
  13. 13. Sr2-Complex for durable APR<br />(Sr2 + other minor genes for durable resistance to stem rust)<br /><ul><li>Sr2 transferred to wheat from ‘Yaroslav’ emmer in 1920s by McFadden and linked to pseudo-black chaff (~ 90years)
  14. 14. Sr2 still provides moderate levels of resistance in Kenya (~30% reduction in disease severity)
  15. 15. Seedling and APR genes with intermediate effects in combination with Sr2 produce enhanced levels of resistance
  16. 16. Formed the basis of durable resistance historically in some CIMMYT wheats</li></li></ul><li>Pyramiding-APR+ Major genes<br />Stem rust severities of SrTmp (n=125) and SrSha7 (n=66) possessing wheat lines in Kenya 2010 <br />APR genes enhance the expression of moderately <br />effective race-specific genes<br />
  17. 17. Identifying materials with adult plant resistance to Ug99<br />Kingbird<br />Greenhouse seedling tests -USDA-ARS Lab. in St. Paul, Minnesota, USA<br />Field evaluations-Kenya/Ethiopia<br />Characterization of PBC phenotype and Sr2 linked molecular markers<br />Identified APR Sources: Kingbird, Kiritati, Juchi, Pavon, Huirivis#1, Muu, Kenya Swara, Kenya Kudu, Parula, Picaflor, Danphe, Chonte<br />
  18. 18. Mapping of Adult Plant Resistance to Stem Rust<br /><ul><li>15 RIL mapping populations developed and phenotyped in Kenya for at least 2 seasons
  19. 19. Genetic studies suggest the involvement of 3 or 4 minor genes in each resistant parent
  20. 20. Initial molecular mapping of six populations completed
  21. 21. Other populations being assigned to graduate students </li></li></ul><li>Methodology<br /><ul><li>Phenotyping conducted in 2009, 2010 field seasons
  22. 22. Artificial epidemics with Ug99+Sr24 (TTKST)
  23. 23. SR severity recorded when 80-100% disease on most susceptible RILs- Modified Cobb scale</li></li></ul><li><ul><li>DArT and SSR markers
  24. 24. Inclusive Composite Interval Mapping (ICIM), Q-gene, QTL Cartographer
  25. 25. ICIM- http://www.isbreeding.net/
  26. 26. Increased power of detection
  27. 27. Additive and Epistatic Effects
  28. 28. LOD Scores>2.5, Probability in step wise regression 0.001
  29. 29. User friendly</li></li></ul><li>PBW343 X Kingbird<br />Kingbird<br />PBW343<br />
  30. 30. PBW343 X Kingbird<br />5B<br />1A<br />3BS<br />7AL<br />7DS<br />PBC<br />
  31. 31. PBW343 X Kiritati<br />Kiritati<br />PBW343<br />
  32. 32. PBW343 X Kiritati<br />7DS<br />3BS<br />2D<br />5BS<br />
  33. 33. PBW343 X Juchi<br />Juchi<br />PBW343<br />
  34. 34. PBW343 X Juchi<br />2BS<br />3BS<br />4AS<br />5BL<br />6BS<br />
  35. 35. Avocet X Pavon 76 (RILs without Sr26)<br />Pavon 76<br />
  36. 36. Avocet X Pavon 76<br />3BS<br />2BS<br />1BL<br />6BS<br />3D<br />5A<br />
  37. 37. PBW343 X Huirivis#1<br />Huirvis#1<br />PBW343<br />
  38. 38. PBW343 X Hurivis#1<br />3BS<br />2BS<br />5BL<br />PBC<br />5D<br />
  39. 39. PBW343 X MUU<br />Muu<br />PBW343<br />
  40. 40. PBW343 X MUU<br />3BS<br />2BS<br />5BL<br />
  41. 41. Inconsistent QTLs<br />4BS-Kingbird<br />2A-Kingbird<br />2D-Kiritati<br />5A-Pavon<br />5DS-Hurivis#1<br />
  42. 42. QTLs summary<br /><ul><li>In total 9 consistent and 5 inconsistent QTLs detected in six mapping populations
  43. 43. QTL on chromosome 3BS in all parents is linked to resistance gene Sr2 & PBC
  44. 44. QTL on chromosome 7DS in Kingbird and Kiritaticonfirms the involvement </li></ul>of Lr34 in reducing stem rust severity (Lr46/Yr29/Pm39 )<br /><ul><li>QTL on chromsome1BL in Pavon 76 and PBW343 suggests the involvement of Lr46 in reducing stem rust severity (Lr34/Yr18/Pm38)
  45. 45. 7 new QTLs identified on chromosomes 1A, 2B, 3D, 4A, 5B, 6B and 7A
  46. 46. 5 inconsistent QTLs identified on chromosomes 2A, 2D, 4B, 5A and 5D
  47. 47. These QTLs in combination with Sr2form the “Sr2-Complex”</li></li></ul><li>Future outlook<br /><ul><li>Saturating genomic regions with additional markers for fine mapping
  48. 48. Development of PCR based assays for flanking markers
  49. 49. Pyramiding APR + major genes using markers
  50. 50. Cloning for resistance gene cassettes</li></li></ul><li>Acknowledgements<br />Agencies supporting rust research:<br />Bill and Melinda Gates Foundation through: <br />DRRW Project<br /><ul><li>Syngenta Foundation
  51. 51. Grain Research and Development Corporation (GRDC), Australia
  52. 52. Kenya Agricultural Research Institute</li></ul>THANK YOU<br />

×