Sess11 2 amele integrative breeding strategy for making climate-smart potato varieties for ssa

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Sess11 2 amele integrative breeding strategy for making climate-smart potato varieties for ssa

  1. 1. Integrative Breeding Strategy for Making Climate-Smart Potato Varieties for SSA 9th APA Conference 30th June –o4 July, 2013
  2. 2. Outline Introduction Understanding downstream adoption challenges Germplasm appraisal Exploring mechanisms and alleles Strategies Conclusion
  3. 3. Outline Introduction Understanding downstream adoption challenges Germplasm appraisal Exploring mechanisms and alleles Strategies Conclusion
  4. 4. Introduction Major African Field Crops Area Growth 1994-2005 (source www.faostat.org) 80 100 120 140 160 180 200 220 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Years Sweet potatoes Potatoes Beans, dry Yams Wheat Cassava Rice, paddy Maize
  5. 5. Introduction Cropping area expansion could come from Replacing other crop Double cropping with irrigation or bimodal RF New areas including to non-optimal cultivation areas (warmers zones) could be negatively affected by global warming linked to climate change Rainfall is becoming more erratic, with longer and hotter dry spells and more intense rainstorms
  6. 6. Introduction Climate change Modify or create new environments Expose the crop to heat stress Drought stress Drought and heat stresses have drastic effects on potato Tissue-specific Whole plant effects Major environmental determinant crop facing now and in future
  7. 7. Introduction Drought stress causes (cf. Monneveux et al. 2013) Decreased plant growth Reduce light use efficiency Shorten crop growth cycle Reduce number and size of tuber
  8. 8. Introduction High temperature (Levy and Veilleux 2007) Accelerates haulm growth Partitioning assimilates towards the haulm Reducing photosynthesis and increase respiration Inhibit tuber initiation and growth Causes tuber disorders Shortening or abolishing tuber dormancy Reduce tuber dry matter Raise level of tuber glycoalkaloid
  9. 9. Introduction Climate model predicts changing climate conditions A global yield reduction b/n 19-32 % estimated to occur due to climate change in first three decades of this century (Hijmans 2003) Projected yield loss would be REDUCED BY 50% with adaptation measures such of USE OF TOLERANCE VARIETIES This highlights the need to improve adaptation to climate variability in potato breeding efforts
  10. 10. Introduction Options for breeders to deal with climate variability Select directly tuber yield Select indirectly for physiological traits that improve yield under climate variability Genomics-based breeding to combine different genes or sets of genes that adapt crop growth to climate variability But growers/farmers need varieties that Adapt well to climate variability at their specific conditions Together with an enhanced level of other desirable traits like consumer and commercial preferences, yield, and resistance to biotic stress
  11. 11. Introduction To combine different option complexity of breeding challenges for each option need to be addressed Drought and heat stresses seldom occur as sole stress factor at farmer field Not yearly event Plants use different physiological mechanisms to adapt Market and consumption preference variation This needs a breeding strategy that integrates knowledge from different disciplines Social science, Plant breeding, Genomics, Physiology, Soil Science, Agronomy, Crop modeling Objective To discuss the design of a breeding strategy that incorporates adaptation traits with the commercial and home use characteristics preferred by potato farmers
  12. 12. Outline Introduction Understanding downstream adoption challenges Germplasm appraisal Exploring mechanisms and alleles Strategies Conclusion
  13. 13. Understanding downstream adoption challenges Breeding programs should be informed of dynamics of adoption challenges for heat or drought tolerance What drives the dynamics? Key processes in farmers variety and seed management and changes that are related to climate in variety use, perception and adaptation strategies Variation in trait preference and their modifications Survey Trait elicitation through exposure to diversity This understanding would help for client-oriented product development in a breeding program
  14. 14. Outline Introduction Understanding downstream adoption challenges Germplasm appraisal Exploring mechanisms and alleles Strategies Conclusion
  15. 15. Germplasm appraisal Level and structure of diversity in available germplasm resource is imperative for harnessing variation Range of tools for a breeding program to uncover diversity Farmer qualitative assessment Which variety grown by whom, where and why and their respective desirable and undesirable characteristics Morphological phenotyping Molecular genotyping SSR marker types proven effective in detecting variabilities in potato (Ghislan et al., 2004, 2009; Lung’aho et al., 2011) Allows designing strategic crossing to mine transgressive segregants based on adapted and preferred germplasm at country or region & to harness the power of heterosis
  16. 16. Outline Introduction Understanding downstream adoption challenges for breeding climate-smart potatoes Germplasm appraisal for breeding climate-smart potatoes Exploring mechanisms and alleles for breeding climate-smart potatoes Strategies for climate-smart potato breeding Conclusion
  17. 17. Mechanisms and alleles Adaptation to climate variability is not a single trait rather overall manifestation of the sum of different mechanisms operating in the plant Trait/allele discovery Which tolerance mechanism exist in the available germplasm? Diploid species S. chacoense S. bertheultii S. microdontum Tetraploid species Andean potatoes adapted to short day conditions possess DT Heat tolerance
  18. 18. Mechanisms and alleles Which tolerance mechanism would farmers prefer in their varieties? Which trait to use as selection objective? How, when and where to measure? Traits need to be measured Managed stress environments (control and stressed) Green houses Field condition with Standardized phenotyping protocols Multi-replication and multi-environment trials
  19. 19. Mechanism and alleles Correlating phenotypic assessment with molecular markers McCord et al. (2010) in tetraploid potato for internal heat necrosis Anuthakumari et al. (2012) in diploid potato for drought tolerance Identified QTL MAB by identifying markers tracking responsible genes
  20. 20. Outline Introduction Understanding downstream adoption challenges Germplasm appraisal Exploring mechanisms and alleles Strategies Conclusion
  21. 21. Integrative breeding design adapted from Asfaw (2011)
  22. 22. Strategies Firm understanding the complexities of targeting How diverse and dynamic are farmer environment and preferences and how to address them? Farmers preference for other traits to integrate with drought or heat tolerance Listening to farmers and considering them as potential partners in variety development Stakeholder participation Knowledge of climate and soil based targeting Use of models that incorporate local climatic conditions and crop management for informed decision
  23. 23. Strategies Defining expectations and goals within each target If yield is 5 tons ha-1 under DT and HT stress Should not worry of “yield potential” of 30 or 40 tons ha-1 Instead think of how to get 10 tons ha-1 under real world condtion as “target yield’’ Look for selection traits contributing to attain “target yield”
  24. 24. Strategies To attain “target yield” Defining genetic structure of varieties Intra-genotypic diversity Increase frequency of genes for DT and HT Intra-varietal Increasing choice for growers
  25. 25. Strategies To determine genetic structure of varieties Smart crossing plan Suitable selection method
  26. 26. Strategies Smart crossing plan Since autotetraploid potato breeding is complex due to its tetrasomic inheritance high heterozygosis and asexual propagation, medium to low h2 estimates for DT and HT traits Need for multiple traits simultaneous selection traditional breeding methods (complementing parental traits or back cross) may not be effective. RECURRENT SELECTION with PROGENY TESTING to identify SUPERIOR PROGENITORS is most effective and practical to manage the complex potato genetic features.
  27. 27. Strategies Smart crossing plan Narrow vs wide Narrow cross Elite x elite cultivar cross In crossing scheme, first identify SUPERIOR CLONES PROGENY TEST to identify those with a high GCA, i.e., GOOD BREEDING VALUE and then, use them as progenitors to cross with several female clones Wide cross Wild/cultivated diploid species Sexual polyploidization Screening for 2n pollens and cross back with tetraploids
  28. 28. Strategies Selection methods Generate series of clones and evaluate under target environment to know what works where to attain the “target yield” Multiple environment testing and farmer participatory breeding Genomic selection Use of high molecular DNA marker information to predict performance
  29. 29. Outline Introduction Understanding downstream adoption challenges for breeding climate-smart potatoes Germplasm appraisal for breeding climate-smart potatoes Exploring mechanisms and alleles for breeding climate-smart potatoes Strategies for climate-smart potato breeding Conclusion
  30. 30. Conclusion Breeding strategy for climate-smart potatoes Understand different aspects of production and productivity and should integrate at different stages of the cycle of breeding Firm understanding of target environment Biophysical and socio-economic Define expectations and goals within each target Smart crossing to combine physiological traits with consumption and market preference traits Generate and introduce diversity to farmers to choose from
  31. 31. Acknowledgment CIP APA
  32. 32. A. Asfaw, M. Bonierbale M.A. Khan International Potato Center

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