1. WARFARIN from moldy hay of sweet clover
Plant of the Day:
Melilotus alba and Melilotus officinalis
infected with
Penicillium nigricans and Penicillium jensi
Family: Fabaceae or Leguminosae
Photos by Elizabeth J. Czarapata

2. WARFARIN from moldy hay of sweet clover
Plant of the Day:
Melilotus alba and Melilotus officinalis
infected with
Penicillium nigricans and Penicillium jensi
Coumarin in sweet clover converted to dicoumarin by molds
Anticoagulant killed cattle in 1920s and 1930s
Karl Paul Link and graduate student Mark Stahmann identified dicoumadins
Named after WARF (Wisconsin Alumni Research Foundation) because they provided $$$
Use as rat poison and then medical use vs. blood clotting (e.g., to prevent heat attacks).
Photo from Johnny’s Selected Seeds

3. Conservation of Crop Genetic Diversity
Why conserve crop genetic diversity?
Example 1
Bridget O'Donnel image from Wikimedia Commons
“Irish Potato Famine” caused by a water mold and by genetic uniformity of potatoes

4. Conservation of Crop Genetic Diversity
Why conserve crop genetic diversity?
Example 2
Southern corn leaf blight epidemic (1970)
USA-wide epidemic leading to a loss of 15% of corn production in USA
Some southern states lost half of crop and half of farmers
Uniformity! All had same cytoplasm (chloroplast genome) because male sterility made hybridization easier.

5. Facing climate change Rice is the major staple for half of humanity
International Rice Research Institute (IRRI), Los Baños, Philippines
Rice is the major staple for half of humanity
Image source:

6. Facing climate change
International Rice Research Institute (IRRI), Los Baños, Philippines
Image source:

7. Drought and disease threaten YOUR coffee.
Photos: Above: Tim Johnson/MCT/Landov Right: Paulo Whitaker/Reuters/Landov Below: International Center for Tropical Agriculture/Flickr

8. Crop wild relatives (CWR)
Figure 1 Genetic bottlenecks imposed on crop plants during domestication and through modern plant-breeding practices.
Genetic bottlenecks imposed on crop plants during domestication and through modern plant-breeding practices. Boxes represent allelic variations of genes originally found in the wild, but gradually lost through domestication and breeding. Such lost alleles can be recovered only by going back to the wild ancestors of our crop species.
S D Tanksley, and S R McCouch Science 1997;277:
Published by AAAS

9. Crop wild relatives
Figure 4 (Left) Wild rice species O. rufipogon from Malaysia. [Photo courtesy of C. Martinez, Centro Internacional de Agricultura Tropical] (Right) Modern rice variety from China.
(Left) Wild rice species O. rufipogonfrom Malaysia. [Photo courtesy of C. Martinez, Centro Internacional de Agricultura Tropical] (Right) Modern rice variety from China. Although wild species are low yielding, they contain genes that can significantly increase the yield of modern rice varieties and provide much needed enrichment of the domestic gene pool.
S D Tanksley, and S R McCouch Science 1997;277:
Published by AAAS

10. Crop wild relatives
Figure 5 (A) Wild tomato species L. hirsutum from Peru that produces small, inedible fruit that does not turn red upon ripening.
(A) Wild tomato species L. hirsutum from Peru that produces small, inedible fruit that does not turn red upon ripening. (B) (Left) Fruit from modern processing tomato cultivar E6203. (Right) Fruit from nearly isogenic line (NIL) into which QTL for increased red pigment has been transferred from L. hirsutum by the advanced backcross QTL method (17). (C) (Top left) Fruit from L. pimpinellifolium from Peru that produces small berries typical of most fruit-bearing wild species. (Top right) Fruit from modern processing tomato cultivar E6203. (Bottom center) Fruit from NIL into which QTL for increased fruit size has been transferred from L. pimpinellifolium by the advanced backcross QTL method. Fruit of this NIL are significantly larger (∼10%) than the original E6203 variety (19).
S D Tanksley, and S R McCouch Science 1997;277:
Published by AAAS

11. History of concern about crop genetic resources since 1970s
Southern corn leaf blight 1970
some southern states lost half of crop and half of farmers
would have been worse if weather had not changed
uniformity due to the use of “T cytoplasm” – male sterility made hybridization easier
IBPGR and CGIAR formed in 1970s
IBPGR, International Board of Plant Genetic Resources
Later IPGRI, International Plant Genetic Resources Institute
Now “Bioversity International”
CGIAR -- Consultative Group on International Agricultural Research
15 International centers CIP, CIMMYT, IRRI, CIAT, etc. and national programs
Grass-roots conservation organizations
Seed Savers Exchange (SSE)
Native Seeds / SEARCH

12. Crop Genetic Resources
Germplasm = “The bearer of the characteristic nature of the species and of the individual” ((Weissman 1883)
Germplasm includes ALL of these:
traditional cultivars (AKA: landraces, primitive cultivars, folk varieties, farmers’ varieties)
wild relatives
weedy relatives
“advanced” or “modern” commercial cultivars
advanced breeding lines, “elite” germplasm

13. The value of genetic diversity
For plant breeders – diversity is the raw material for future crop improvement
Landraces (= traditional or folk cultivars) with traits for pest resistance, yield, flavor, nutrition, drought resistance, salinity tolerance, etc.
An example: Harlan’s “miserable” wheat in handout.
Wild relatives have contributed to crops genes for disease and pest resistance, wider adaptation (climate), improved quality (protein, oil, flavor, soluble solids), self-fertility, short stature, etc..
Surprising alleles (e.g., alleles to improve cotton fibers from wild relatives that do not have fibers on seeds.)

14. Harlan’s “miserable wheat” quote

15. The value of genetic diversity
For traditional farmers – diversity for food security
adaptation to specific local conditions (deeply rooted Hopi maize)
risk reduction – dependable harvest in unfavorable conditions (see handout example)
favored foods, symbols of identity
may be more suited to marginal lands and conditions than “Green Revolution” HYV (high yielding varieties), which are not necessarily efficient in scarce resources (require high inputs of water and nitrogen)

16. Hernandez-X. quote (cited by Wilkes)

17. Two complementary conservation strategies:
Ex-situ conservation
= collecting and preserving in germplasm banks, botanical gardens, etc. (not in the plant’s natural habitat)
In-situ conservation
= “in place” or “on farm” landraces on traditional farms, wild species in their natural habitats

18. Conservation of crop diversity “ex-situ” in gene banks
Conservation of crop genetic diversity
Conservation of crop diversity “ex-situ” in gene banks

19. USDA National facility in Fort Collins, Colorado
National and international germplasm banks preserve crop diversity “ex-situ”
Cary Fowler/Global Crop Diversity Trust (both on left);

20. Ultimate backup “ex-situ” facility in the arctic:
Svalbard Global Seed Vault
Global Crop Diversity Trust

21. Conservation of crop diversity “in-situ” = on farm

22. Ex-situ conservation
Advantage: accessible for plant breeders for future plant improvement
evaluation of traits (morphological, molecular, agronomic, nutritional, etc.)
changing values means that “worthless” ones may turn out to be valuable (high lysine corn, resistance to new pests)

23. Ex-situ conservation Ex-situ conservation
Pitfalls of ex-situ conservation
lose variability due to genetic drift as only a small portion is grown out
selection for ability to retain viability in storage
grow-out conditions unlike those of traditional farmers on marginal lands (not evolving in response to natural environmental conditions)
mistakes, human error leads to losses
budgetary constraints, political instability
(Threats to Pavlovsk germplasm in Russia, unrest or war, e.g., Aleppo germplasm bank in Syria.)

24. In-situ conservation
Now widely seen as an important complement to ex-situ conservation.
allows continued evolution in response to changing environments (new pathogens, pests, stresses)
keep crops in their “cultural-ecological context” the human-modified systems in which they evolved
ecological complexity of traditional agriculture, use of micro-habitats
accessible to traditional farmers (although less accessible to plant breeders)
***Please see handouts and other readings for more nuanced discussion.

25. Grassroots seed saving efforts
Contribute to grassroots seed-saving organizations

26. Try it yourself
Learn to save seed of your own vegetables (some are easy).
Photo source: Paul Gepts, UC Davis
Photo courtesy Linda Black Elk