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Germplasm Enhancement of Maize: Encountering Ways to Select within Landraces

Discover methods for improving maize landraces through germplasm selection. Explore phenotypic characterization, adaptation, and major collaboration efforts in maize breeding.

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Germplasm Enhancement of Maize: Encountering Ways to Select within Landraces

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  1. Germplasm Enhancement of Maize:Encountering Ways to Select within Landraces Martha C. Willcox Maize Landrace Improvement Coordinator

  2. Important considerations in utilization of exotic maize germplasm • Understanding of available variation. Racial Groups, Geography, Environment, Genomic • Good phenotypic characterization of the variation Yield and Agronomics, Biotic and Abiotic Stress, Specific quality 3. Managing adaptation differences Grouping by adaptation, backcrossing to adapted, selection and manipulation of environments for evaluation

  3. Methods of addressing these considerations

  4. Three Major Areas of Work: • Topcross Phenotyping for GWAS- Seeds of Discovery • Family formation from accessions for specific traits • Accession Per Se Phenotyping • Based on environmental Selection • Characterization of accessions of major races • Participatory Plant Breeding • Selecting within farmer samples and improving agronomics • Linking farmers to markets based on culinary quality

  5. Seeds of Discovery

  6. CIMMYT:JuanBurgueno, Armando Guadarrama, Daniel Chepetla, Enrique Rodriguez,Dan Jeffers, George Mahuku, Iván Ortiz-Monasterio, Natalia Palacios, Félix San Vicente, Rosemary Shrestha, Samuel Trachsel, Sarah Hearne, Peter Wenzl INIFAP: Noel Gómez, Alejandro Ortega, Ernesto Preciado, Víctor Vidal Pioneer-Mexico: FernandoGonzález, Heriberto Torres, Marco Oropeza Gates Foundation: Gary Atlin UAAAN-UL: Armando Espinoza Banda Bidasem:María E. Rivas-Dávila ICAMEX:Francisco Javier Manjarrez Productores de Semilla de Copandaro: Humberto Vallejo Collaborators:

  7. Genome Wide AssociationStudy(GWAS) in Maize • Breeder’s Core Collection from the CIMMYT Maize Germplasm Bank (4471 accessions). • Oneplant per accessioncrossedwith a CIMMYT hybrid to make a series of modifiedtopcrosses. • Thesameplantwassampledfor DNA extraction/GBS • Accessions were crossed to hybrids of their same environmental adaptation (where possible). Tropical Accessions X Tropical Hybrid Subtropical Accessions X Subtropical Hybrids Highland Accessions X Highland Hybrid

  8. Accessions Comprising the Breeder’s Core Collection Wereselectedbasedonagronomicperformance by Taba. Abouthalftheaccessions are fromthelowlandtropicswiththeremainersplitbetween subtropical and highlandaccessions.

  9. 115o 110o 105o 100o 95o 90o 85o 30o 30o 25o 25o El Batán, Mex 20o 20o Agua Fría, Pueb Tlaltizapán, Mor 15o 15o Drought 100o 115o 110o 105o 95o 90o 85o TrialSites in Mexico: GWAS Obregon, Sonora Drought; Heat Heat & Drought Stalk Rot; Quality Torreon, Coahila Low Nitrogen, Ear Rot, Quality, Turcicum San Pedro Lagunillas, Nay Cercospora Celaya, GTO Cortazar, GTO Numaran, MI Low Nitrogen Almoloya, Mex Tarimbaro , Michoacan Stalk Rot Iguala, GRO Guadalupe-Victoria, Chiapas Tar Spot Complex Ocotito, Guerrero

  10. Phenotypic Trials • 36 trials planted - 34 harvested (34,606 rows and over 687,000 unique data points) • 19 Trials for abiotic Stresses (Drought, Heat, Low Nitrogen) • 11 Trials for diseases (Tar Spot Complex, Grey Leaf Spot, Turcicum Leaf Blight, Fusarium Ear Rot, Fusarium and Acremonium Stalk Rot) • 3 Trials hand pollinated to produce grain for Quality Component Analysis.

  11. Yield and Agronomic Data Taken : All Locations • Yield (field weight, grain and cob weight, moisture, number of ears) • Plant Height and Ear Height • Male and Female Flowering (50% of row) • Stalk and Root Lodging

  12. Experimental Design • Unreplicated augmented row-column design • For each trial location accessions are selected for adaptation zone and maturity. • Overlapping sets of topcross entries • Two widely adapted commercial checks and resistant and susceptible checks where appropriate

  13. Example of Trial Design Standard commercial checks ( and ) to adjust for spatial variance and link trials from multiple locations and trait specific, resistant ( ) and susceptible ( ) checks, to adjust for spatial variation for specific traits within the trial.

  14. Challenges • Range of maturities (flowering extends for 5 weeks) • Lodging • Segregation • Diversity of environments (both origin of accessions and evaluation sites).

  15. Tar Spot Complex

  16. Tar Spot Complex Photo: Rosemary Shrestha

  17. Tar Spot Trials • 2011B Guadalupe-Victoria, Chiapas – 600 Accession/Topcross entries • 2012B Guadalupe-Victoria, Chiapas – 810 accession/topcross entries (including accessions per se) • 2 foliar ratings 0-5 scale (Ceballos and Deutsch) two weeks apart. • Data taken both by row and as average of 6 plants per row

  18. (CML269/CML264)/Oaxa280 (CML495/CML494)/Guat153 Yield(g/plot) Guat153 Oaxa280 Relationship between Tar Spot rating and Yield (2nd foliar rating: scale 0-5; average of 6 plantas) =Accessions; = Topcrosses; = Commercial Checks Tar Spot Foliar Rating (0-5)

  19. Accessions by Race: Min-Mean- Max Tar Spot Ratings

  20. 2ndTar Spot Rating Foliar in 2012 (6 individual plants 0-5 rating scale)

  21. 2014 Trial for Confirmation of Resistance to Tar Spot • Selections from previously unevaluated portion of GWAS for Tar Spot. • Selected for favorable allele at 5 highly significant associations sites. • Null selected based on genotypic and phenotypic similarity to resistant accessions but with out favorable alleles at the 5 significant SNP.

  22. 5 4 Tar spot second foliar rating 3 2 None C3_ 2861473 C8 _138133667 All C1_287736035 C5_19462129 C10_134718316 Arrowsindicatethegenomiccompositionthat has a statisticalsignificantdifference in the mean comparedwiththe control (None)

  23. Correct Defects with Improved material Most resistant material for Tar Spot Complex has a lodging problem Crossed to CML 9, CML 503, CML 264, CML 324, CLWN 247 for stalk strength Backcrossed to the accession (and CML –T.Molnar) Produced S1s for evaluation 2015 Evaluate BC1S1s under heavy disease pressure (Chiapas) Best BC1S1 families to recombine Oaxa280

  24. Oaxa280 x CLWN 247 BC1S1 Guat 153//CML9/Guat153

  25. Crosses in Progress for Tar Spot - USA • Oaxa280//Oaxa280/CML324 Oloton/Conico -resistant to Tar Spot collectedfrom 1700 maslby CML 324 Subtropical Non Tuxpeño Planted to cross with: • LH123HT –non-stiffstalk • PHHB9- stiffstalk In collaboration with Univ. of Illinois - Santiago Miderosand Tiffany Jamann

  26. Evaluation under Low Nitrogen

  27. Evaluation of Highland Topcrosses under Low Nitrogen Testcrossesss Landrace Imp Yield tons/ha: Low Nitrogen Hybrid Imp Checks Yield tons/ha: Optimal Nitrogen

  28. 8 6 Low Nitrogen Yield (t/ha 12.5%Hr) 4 2 (CML457/CML459)//CHWE239 0 HIDA88 MEXI520 HIDA141 HIDA158 AGUC90 TLAX244 PUEB480 PUEB507 PUEB533 XR10CERES DURA150 DURA159 GUAN166 S07HEYLN S1 lines from Highland Accessions under Nitrogen Stress 2014 S1s Per se Checks

  29. Durango-159, S1 under Low Nitrogen Stress

  30. Progress in Low Nitrogen Selection for Highland Accessions • Best S1 lines are being recombined • Best S1 lines topcrossed to Highland Testers

  31. Per Se Evaluations • Directevaluation of traits of interestto look for new sources of favorable alleles. • Evaluatetheaccessionthroughplantingbulkseedfromtheaccession.

  32. Selection of Accessions from Semi-Arid Regions Raton Apachito Ruiz et al. 2013 Chapalote, (CONABIO)

  33. In Vitro Digestibility By Race of Stover Laboratory data from Natalia Palacios - CIMMYT

  34. ParticipatoryPlantBreeding of NativeMaizes in Marginalizedareas of Oaxaca Martha Willcox Coordinadora, MaícesNativos

  35. Collaborators M.C. Flavio Aragón INIFAP Ing. Humberto Castro UACH M.C. Leodegario Osorio INIFAP

  36. Participatory Breeding Agronomic Improvement Genetic and Agronomic Improvement of native maize in Oaxaca, Mexico Access to Market End User

  37. Market Opportunities

  38. Enrique Olvera of Best New Restaurant Nominee Cosme Restaurant Review: Cosme in the Flatiron District There are no tortillas remotely like this in New York. Cosme makes them downstairs in the kitchen from old strains of blue, yellow, purple and white corn grown in Mexico.

  39. Foto: Flavio Aragon

  40. USAID BuenaMilpa Project in Guatemala

  41. Thank you

  42. Mexican Accessions: Fiber, Digestibility, and Lodging Laboratory data from Natalia Palacios - CIMMYT

  43. Characterizationfor Stalk Rot

  44. Fusarium Stalk Rot: Artificial Inoculation

  45. Yield (t/ha 12% hum) Stalk Rot Scale (proportion of stalks with Acremoniumstrictum times intensity 1-5) Relationship between Yield and Stalk Rot Scale (percentage of stalks with disease x intensity of disease) =Topcrosses ; = Commercial Checks

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