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Spring Bread Wheat Improvement for Irrigated Environments

Spring Bread Wheat Improvement for Irrigated Environments. Ravi Singh, Julio Huerta, Sybil Herrera, Pawan Singh, Govindan Velu , Sukhwinder Singh and Sridhar Bhavani. Wheat Breeding at CIMMYT. Mexico based Irrigated spring bread wheat improvement Rainfed spring bread wheat improvement

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Spring Bread Wheat Improvement for Irrigated Environments

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  1. Spring Bread Wheat Improvement for Irrigated Environments Ravi Singh, Julio Huerta, Sybil Herrera, Pawan Singh, Govindan Velu, Sukhwinder Singh and Sridhar Bhavani

  2. Wheat Breeding at CIMMYT Mexico based • Irrigated spring bread wheat improvement • Rainfed spring bread wheat improvement • Durum and triticale improvement • Germplasm enhancement Regional based • Turkey-CIMMYT-ICARDA winter and facultative wheat improvement for CWANA region • CAAS-CIMMYT winter and facultative wheat improvement for China

  3. Spring wheat mega-environments • ME1: Irrigated (36.1% area) Temperate 1. High yield potential, lodging tolerance 2. Water and nutrient use efficiency 3. Resistance to three rusts 4. Large white grain with leavened and flat bread quality

  4. Spring wheat mega-environments • ME2: High rainfall >500 mm (8.5% area) Temperate 1. High yield potential, lodging tolerance 2. Resistance to three rusts, septoria tritici and fusarium head blight 3. Large red grain with leavened bread quality

  5. Spring wheat mega-environments • ME5: Irrigated or High rainfall (7.1% area) Warmer 1. High yield potential with early maturity, lodging tolerance 2. Heat tolerance 3. Resistance to rusts and spot blotch for low rainfall areas Resistance to rusts and fusarium head blight for high rainfall areas 4. Large white or red grain with leavened and flat bread quality or noodle quality depending on the country

  6. Irrigated Spring Bread Wheat Improvement Program- Targeted area: 45 m ha • Irrigated Mega-environment 1:China, North-western India, Pakistan, Afghanistan, Iran, Turkey, Egypt, Mexico and Chile:30 m ha • Irrigated (Warmer) Mega-environment 5:North-eastern, Central and Peninsular India, Tarai of Nepal, Bangladesh, Southern Pakistan, Sudan:10 m ha • High rainfall Mega-environment 2:West Asia and North Africa, Highlands of East Africa:5 m ha

  7. Breeding Priorities • High and stable yield potential • Durable disease resistance • Rusts- Stem (Ug99), Stripe and Leaf • Fusarium – Scab and myco-toxins • Septoria leaf blight, Spot Blotch, Tan Spot • Karnal bunt • Water use efficiency/Drought tolerance • Heat tolerance • Appropriate end-use quality • Enhanced Zn and Fe concentration • Adaptation in conservation Agriculture • Human Resource Development

  8. Ciudad Obregon-Toluca/El Batan “Shuttle Breeding”: Backbone of CIMMYT Wheat Improvement • Hot-spot screening- Ecuador (YR), Kenya (SR) • International testing through yield & screening nurseries Cd. Obregón 39 m, High yield (irrigated) Drought tolerance Leaf rust, stem rust El Batán 2249 m Leaf rust, Fusarium Mexico City Toluca 2640 m Yellow rust Septoria tritici Fusarium zero tillage with maize stubble

  9. Why increase yield potential? • Necessary to meet the increasing demand (2% annual) due to population increase • Increased production must come from the existing or reducing land resources • Increased yield potential is reflected in yield increases in farmers’ field even though the management remains the same

  10. How to protect gains in yield potential? • Resistance to important diseases and pests (biotic stresses) • Tolerance to drought, heat, salinity, etc (abiotic stresses) • Resistance and tolerance to stresses in a variety has no cost to farmers

  11. Yield stability • Capacity of a genotype (variety) to perform well under a range of environments under existing biotic and abiotic stresses • Environment at a location fluctuates annually • Easiest way to determine yield stability is to evaluate yield performance under a range of environments (wide adaptation)

  12. Type of Crosses • Simple, three-way and four-way crosses: an attempt to create new combinations of desirable genes (creation of a distinct genotype) • Backcross: adds a genes or few genes from a source into an existing genotype • Single-backcross: maintains most characteristics of a variety but still allows selection for several new genes

  13. The Single-backcross Strategy • Increases the possibility of maintaining and reselecting desirable genes of the recurrent parent • Multiple genes or characters can be transferred simultaneously • Additional genes or characters from the donor parents can also be selected

  14. Grain yields of wheat lines developed through traditional (Simple and 3-way crosses) and single-backcross approach 0.8% > Check 10.7% > Check Cd. Obregon 2004-2005

  15. Crossing details • Approximately 600 targeted simple crosses, 500 single- backcross or three-way crosses per crop season • Approximately 300 F2 populations from simple crosses and 400 from single-backcross and three-way crosses • High emphasis to incorporate durable stem rust resistance in a range of germplasm carrying high yield potential, durable LR and YR resistance and quality characteristics

  16. Selection Schemes • Various selection schemes can be applied • Selection schemes commonly used: pedigree, unselected-bulk, selected-bulk, modified pedigree or bulk • Our preferred strategy: selected-bulk

  17. Selection Method:Selected Bulk(Harvest and thresh one spike from each of the selected plants of a population as bulk) • Permits selection of unlimited number of plants that have good agronomic features and desired level of resistance • Increases possibility to identify transgressive segregants due to larger population sizes • Field operation is easy, fast and economic

  18. Genetic gain in yield from Selected Bulk is 3.3% higher than Modified Pedigree(Source: Simulation studies- J. Wang and M. van Ginkel, Crop Science)

  19. Selected bulk retained 25% more crosses in the final selected population (Source: Simulation studies- J. Wang and M. van Ginkel)

  20. Selection Strategy in Segregating Populations • Selected bulk from F1BC1/F1Top until F4/F5 • Population sizes: Space sown 400 plants in F1BC1/F1Top and F3-F5; 1200 plants in F2 (2 million plants/season with an average selection frequency of about 7-10%) • Alternate segregating generations (F2-F5) under zero-tillage with maize stubble in Toluca and normal tillage in Cd. Obregon • Shuttling of stem rust resistance breeding F3 and F4 populations with Njoro, Kenya; grown in off-season and then main season as F4 and F5. F5 and F6 at Obregon. • Grain selection for size (45 mg and above) and plumpness in each generation through sieving • Selected plants harvested individually (or one spike harvested in Toluca) in F5 and F6 generations and plants/spikes with good grain characteristics retained

  21. Handling of Advanced Lines • Advanced lines (F6) from individual spikes in F5 populations harvested in Toluca planted in Cd. Obregon as small plots. Selected plots planted in Toluca and El Batan as PC. Selected lines form yield trials in Cd. Obregon. • Advanced lines (F5 or F6) from individual plants harvested in Cd. Obregon planted as F6/F7 at El Batan and Toluca in small plots and selected lines form yield trials in Cd. Obregon. • Yield trials-1st year (alpha-lattice design, 3 reps) sown on raised bed system in Cd. Obregon, and sets of PC are grown in Cd. Obregon (leaf rust) • Best lines selected based on yield and other traits and grain from Cd. Obregon used for quality analysis and for further disease and agronomic evaluations at Toluca, El Batan and Njoro (Kenya); and also multiplied in El Batan as Candidates for International Yield and Screening Nurseries (ESWYT, IBWSN, HRWYT, HRWSN) • 2nd year of yield trials in Cd. Obregon for selected lines conducted under five environments and seed multiplied in Mexicali for International Nursery. Simultaneous stem rust, yellow rust and leaf rust testing conducted in Kenya, Ecuador and cd. Obregon, respectively. • All data combined and used in selecting lines for International Yield Trials and Screening Nurseries

  22. Yield testing of advanced lines at Cd. Obregon, Mexico2009-2010 season • 1st year yield trials or YT (5000 entries including checks): 30 entries/trial, 3 reps, alpha-lattice design • raised bed 5-irrigations (small plots or PC planted for seed) • 2nd year yield trials or EYT (500 entries including checks): 30 entries/trial on beds (20 entries trial on Flat), 3 reps, alpha-lattice design • Raised bed, zero tillage-5 irrigations (>8 t/ha) • Flat-5 irrigations (>8 t/ha) • Raised bed-2 irrigations (4-5 t/ha) • Raised bed- drip irrigation (2.5-3 t/ha) • Raised bed-Late (85 days delay) sown- (>4 t/ha) (small plots or EPC planted for seed)

  23. Characterization of EPC entries • Diseases: • Leaf rust- seedling and field (El Batan and Cd. Obregon) • Yellow rust- seedling and field (Toluca and Ecuador) • Stem rust- seedling and field: off- and main-seasons (Kenya) • Septoria tritici- Toluca • Fusarium- El Batan • Karnal Bunt- Cd. Obregon • Tan (yellow) spot- El Batan greenhouse • Stagnospora nodorum blotch- El Batan greenhouse • Spot blotch- Aguas Frias • Various quality traits including grain weight • Agronomic traits: height, heading, maturity, lodging

  24. Progress in grain-yield potential of new breeding lines after one 5-year cycle of selection (Cd. Obregon 2004-05 and 2009-2010) Breeding is science, art, passion, hard work & number game 12% yield gain 2004-05 4814 entries 2009-10 4956 entries 0.6% 8.9% PBW343

  25. Shifting towards larger kernelsKernel weight of 1254 entries selected from 2009-2010 1st year yield trials at Cd. Obregon, Mexico PBW343

  26. Canadian Australian CIMMYT 1990s CIMMYT 2000s Accumulation of favorable alleles of High Molecular Weight (HMW) glutenins Wheat glutenins high frequency of poor LMW glutenins high frequency of good LMW glutenins Quality profiles of newer CIMMYT wheats Changing profiles of high and low molecular weight glutenins in CIMMYT wheats for bread making quality as well as reduction of 1BL.1RS translocation Source: R.J. Peña

  27. Variation for loaf volume of 486 new wheat lines grown in Cd. Obregon during 2008-2009

  28. Predicted expansion of heat-stressed wheat ME5 mega-environment in India Current 2050

  29. Future Gains in Yield Potential and Yield Stability under Climate Change • Targeted improvement of high yielding, widely adapted wheats: Identifying superior transgressive segregates • Wide incorporation of white floured 7DL.7Ag alien segment carrying Lr19/Sr25 genes: quantum jump of 10-12% in yield potential • Utilization of genetic resources, e.g. synthetic wheats • Shifting maturity towards earliness and selecting under heat-stress at hot-spot sites • Application of physiological tools in selection • Variety mixtures must be explored as an alternative strategy in heat and other stressed environments

  30. Segregating populations for selection in Toluca in 2010

  31. Advanced lines for selection in Toluca & El Batan in 2010

  32. Future Challenges- The Population Monster Countries with highest population in 2050 and change relative to 2009 620 million more people just in South Asia by 2050 = Population of USA and Brazil in 2009

  33. Future challenges- Wheat Yields: 2008 Average by 2020 to produce 760 mlln tons World average 2008 UN/FAO production goal for wheat 4 tons/ha by 2020

  34. Rust menace- continued fight with an old enemy Brown (leaf) rustPuccinia triticina Yellow (stripe) rustPuccinia striiformis Black (stem) rustPuccinia graminis

  35. Dr. Roy Johnson (1935-2002) Durable Resistance Resistance, which has remained effective in a cultivar during its widespread cultivation for a long sequence of generations or period of time in an environment favourable to a disease or pest. Types of Resistance • Monogenic ≈ Race-specific ≈ Major genes ≈ Hypersensitive (Boom & Bust) • Polygenic ≈ Race-nonspecific ≈ Minor genes ≈ Slow rusting/ Partial(Durable)

  36. “Boom-and-Bust”: Race-Specific Genes for leaf rust resistance in Northwestern Mexico

  37. Durable Resistance to Rust Diseases: Why? • Numerous races of rust pathogens • Mutating and migrating nature of rust pathogens • Annual virulence analysis and monitoring required • Most known race-specific genes ineffective in one or more wheat growing regions • Slow variety turnover in many countries • Opportunity to break-out of “Boom-and-Bust” cycles and focus breeding for other important traits

  38. Genes involved in durable, slow rusting resistance to rust diseases • Minor genes with small to intermediate effects • Gene effects are additive • Resistance does not involve hypersensitivity • Genes confer slow disease progress through: 1. Reduced infection frequency 2. Increased latent period 3. Smaller uredinia 4. Reduced spore production

  39. With Lr46 Without Lr46 Pleiotropic Slow Rusting Genes:Lr34 /Yr18/Pm38 and Lr46/Yr29/Pm39Lr67/Yr46/Pm? • Components of slow rusting are under pleiotropic genetic control, i.e., the same resistance mechanism controls all components • Formation of cell wall appositions, instead of hypersensitivity

  40. Leaf tip necrosis and slow rusting resistance • Lr34/Yr18/Pm38, Lr46/Yr29/Pm39 and Lr67/Yr46/Pm? linked to some level of leaf tip necrosis expression • Slow rusting resistance without leaf tip necrosis also known Leaf tip necrosis associated with Lr46 Lalbahadur Lalbahadur+Lr46

  41. Identification and characterization ofslow rusting resistance • High or susceptible infection type in the seedling growth stage • Lower disease severity or rate of disease progress in the field compared to susceptible check • Brown rust: High (compatible) infection type in the field • Yellow rust: Infection type not a reliable criteria due to systemic growth habit • Stem rust: Variable size of pustules- bigger near nodes

  42. Genetic basis of durable resistance to rust diseases of wheat % Rust Susceptible 100 80 1 to 2 minor genes 60 40 2 to 3 minor genes 20 4 to 5 minor genes 0 20 0 10 30 50 40 Days data recorded Relatively few additive genes, each having small to intermediate effects, required for satisfactory disease control Near-immunity (trace to 5% severity) can be achieved even under high disease pressure by combining 4-5 additive genes

  43. Advances in Molecular Mapping of Slow Rusting Resistance Genes • Several Genomic locations (QTLs) known • Developing and characterizing mapping populations that segregate for single resistance genes • Single gene based populations for 2 or 3 undesignated genes now available at CIMMYT • Very difficult to characterize populations segregating for minor genes that have relatively small effects • Gene-based markers for relatively larger effect slow rusting genes becoming reality • Gene Lr34/Yr18/Pm38 cloned and gene-based marker available • Significant progress made towards cloning of Lr46/Yr29/Pm39

  44. Durable pleiotropic resistance gene Lr34/Yr18/Pm38 Perfect marker for Lr34 -veLr34sp & +veLr34spA (multiplex) ABC (ATP Binding Cassette) transporter of PDR (Pleiotropic Drug Resistance) subfamily 1 2 3 4 5 6 Cloning of Lr34/Yr18/Pm38 • Single gene based fine mapping populations • Gamma-ray induced deletion stocks • Azide-induced mutations • Precision phenotyping • Partnership (CIMMYT, CSIRO and Univ. of Zurich) • Lalbahadur • Lalbahadur+Lr34 • Thatcher • RL6058 (Thatcher+Lr34) • Chinese Spring (+Lr34) • Lr34 deletion mutant Krattinger et al. Science 2009

  45. Advances in breeding for slow rusting resistance to brown and yellow rusts at CIMMYT • 1970s: Wheat lines with intermediate levels of slow rusting resistance selected. • 1990s: Wheat lines with near-immune level of resistance developed through intercrossing diverse sources of resistance followed by selection of transgressive segregants. • 2000s: Targeted introgression of resistance into adapted cultivars and genotypes resulting in high-yielding wheats with high levels of resistance.

  46. Controlled field epidemics remain the best tool for selecting slow rusting resistance

  47. Adult plant leaf rust responses of 144 race-specific gene carrying and 360 seedling susceptible new elite entries in El Batan, Mexico 2009 Susceptible checks = 100% severity 0-15% severity

  48. Variation in resistance to yellow rust in 504 new elite entries tested during 2009 Severity of susceptible checks =100S (N)

  49. Iran 2007 Pakistan Ug99: migration and evolution: current status • 1988: Uganda • 2002: Kenya • 2003: Ethiopia • 2006: Yemen and Sudan • 2006: Sr24 virulent mutant-Kenya • 2007: Iran • 2007: Sr36 virulent mutant-Kenya • 2007: Sr24 virulent mutant-caused epidemic in Kenya • 2008 & 2009: Similar races found in South Africa 2006 Yemen Sudan 2006 2003 1998 2002

  50. Why Ug99 is a threat to wheat producing countries? • Historical importance of stem rust • Span of susceptible wheat varieties on >80% area • Favorable environment (dew/rain and temperatures) • Mountains and other areas for off-season survival • Continued evolution • Early epidemics can cause >70% losses • If measures not taken, estimated 10% losses in production in South Asian countries alone can be worth approx. US$1.5 billion and will provoke sharp increases in wheat prices

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