1. Integrative Breeding Strategy for Making
Climate-Smart Potato Varieties for SSA
9th APA Conference
30th June –o4 July, 2013

2. Outline
Introduction
Understanding downstream adoption
challenges
Germplasm appraisal
Exploring mechanisms and alleles
Strategies
Conclusion

3. Outline
Introduction
Understanding downstream adoption
challenges
Germplasm appraisal
Exploring mechanisms and alleles
Strategies
Conclusion

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. 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. 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. 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. 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. 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. 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. 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. Outline
Introduction
Understanding downstream adoption challenges
Germplasm appraisal
Exploring mechanisms and alleles
Strategies
Conclusion

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. Outline
Introduction
Understanding downstream adoption challenges
Germplasm appraisal
Exploring mechanisms and alleles
Strategies
Conclusion

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. 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. 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. 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. 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. Outline
Introduction
Understanding downstream adoption challenges
Germplasm appraisal
Exploring mechanisms and alleles
Strategies
Conclusion

21. Integrative breeding design adapted from Asfaw (2011)

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. 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. 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. Strategies
To determine genetic structure of
varieties
Smart crossing plan
Suitable selection method

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. 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. 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. 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. 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. Acknowledgment
CIP
APA

32. A. Asfaw,
M. Bonierbale
M.A. Khan
International Potato Center