The slides from my crop domestication lectures in FRC1010

1. Crop DomesticationCrop Domestication
From Wild Weeds to High QualityFrom Wild Weeds to High Quality
FoodFood
Kevin M. FoltaKevin M. Folta
Department of Horticultural SciencesDepartment of Horticultural Sciences
Plant Molecular and Cellular Biology ProgramPlant Molecular and Cellular Biology Program
University of FloridaUniversity of Florida
kfolta@ifas.ufl.edukfolta@ifas.ufl.edu

2. What is “Natural” when we talk about food?

3. What is Domestication?
Def- is the process whereby a population of animals or plants,
through a process of selection, becomes accustomed to human
provision and control.
Agriculture Accelerated
the Human Condition
From Kates, 1994

4. My Definition
Domestication leads to the production of plant
parts that are more beneficial to humans than
the parts produced by wild antecedents.
Me, 2010

5. What are traits that early farmers may have
selected?
decreased plant stature, loss of photoperiod
sensitivity, loss of seed dormancy, and most
notably, a dramatic increase in the abundance,
length, and quality of seed epidermal fiber
http://www.eeob.iastate.edu/faculty/WendelJ/fiberevolution.htm

6. What are some traits engineered into
domesticated crops?
Larger size of organs used- leaves, fruits, roots, tubers
Change in color
Accumulation of flavors or nutrients (also sometimes a loss).
Loss of toxic or bitter compounds
Loss of seed dispersal mechanisms
Synchronous flowering and/or ripening
Synchronous germination
More desirable food forms (loss of protective tissues or seeds)

7. Types of Domestication
Incidental- Didn’t happen on purpose. Hunter/gatherers dropped
seeds, scared off natural herbivores, disrupted natural
environments so that plants could grow.
Directed- Humans and plants became dependent on each other, so
better plants helped people get healthier, planting more (and
maybe improved) plants, etc.
Agriculture- Human intervention in crop husbandry. Cultivation.
Selection.

8. Where did Domestication Start?
Grains of rye with domestic traits recovered from 11,000BC
The bottle gourd (Lagenaria siceraria) was a container before
ceramics and was cultivated in Asia and moved to the new world
with migration.
Peas and wheat in the Middle East, 9000 BC
Fruit trees (apples, apricots), rice, soy, beans, etc.
Strawberry domesticated by non-native people about 250 years
ago.

9. Most of them are aliens!

11. (at least) Three major crops
have genetic roots in
Mexico

13. Corn domestication started at least 10,000 years ago in Mexico
Oldest archeological evidence in Tehuacan in Central Highlands
Radiated rapidly throughout Mesoamerica
Main subsistence of Mayans and Azetcs

14. Teosinte
Modern maize

15. Brassica oleracae

17. Floral reversion in ag-1 mutant backgrounds
Parcy F et al. Development 2002;129:2519-2527

18. Barley
Wild species in the Near East and Middle East, cultivated from
Palestine, Iran, Iraq, Syria, Israel, Jordan, Turkey; 10,000 years
ago.
Domestication brought non-brittle ears (some evidence
suggests that this happened in two separate places)

19. Two-Row and Six Row Barleys
Two genes control the difference between a
barley head that produces two rows of grains
and six rows of grains.
Selection of the six-rowed type was a critical
point of cultivation.

20. What was the driving force behind barley
domestication?
Sumerian tablet, 4000 BC

21. What is this?

23. Bananas!
Archeological and other evidence
indicates that bananas have been
cultivated for over 7000 years. Cultivation
started in Southeast Asia.
The modern banana came from when
diploid domesticated bananas
spread into the range of wild
bananas.
Domesticated (genome = AA)
Wild (genome = BB)
Modern banana = AAB and ABB
triploids! (that’s why they are
infertile)

24. What is this one?

25. What is this one?

26. Origins of Cultivated Strawberry
Fragaria chiloensis
Fragaria virginiana
1714
1534, 1588
8x = 56
1759 “Fragaria × ananassa Duchesne”

27. What is this one?

28. Tomato (Solanum lycopersicum)
Originated in the Andes Mountains
Brought north to Mexico by native people ~2000 years
ago
Belong to Solanaceae, the nightshade family, so many
wild relatives are poisonous.

29. Lycopersicon cheesmanii
Lycopersicon parviflorum
High Vitamin C, tiny fruits
High Vitamin C, tiny fruits, drought tolerant
Tiny fruits, drought tolerant
Lycopersicon pennellii

30. Although from the Americas
(Peru) it was not cultivated until
it was brought to Mexico.
Europeans brought it back from
the New World and eventually it
made its way back to the USA.
It was not consumed in the
USA until almost 100 years
ago. Everyone thought it was
poisonous.

31. Comparisons to wild
relatives brings new
opportunities for changes
in flavors, disease
resistance, etc.

32. What are these?

33. Amazing variation in wild potatoes
Tremendous gains
from breeding

34. Lake Titicaca is the
place where humans
first likely cultivated
potatoes. This is on
the border of Bolivia
and Peru.
~7000 years ago.
Chuño – smashed potatoes
with feet, frozen and dried.B MY
SPUDBOY

35. Potatoes
Cultivated by indigenous people in
South America, but then brought to
Europe by the Spanish in 1500’s. It
came back to North America in the
1600’s and was not a domesticated
crop in North America until 1719 when
Scotch-Irish settlers grew it in New
England.

36. Breakthrough Gains by Luther Burbank in 1870’sBreakthrough Gains by Luther Burbank in 1870’s
Planted 23 seedlings from a strange ‘Early Rose’Planted 23 seedlings from a strange ‘Early Rose’
potato plant that set seedspotato plant that set seeds
Noted one that made 2-3x more tubers than othersNoted one that made 2-3x more tubers than others
Sold the rights for $150Sold the rights for $150
Now it is still the most popular potato, the IdahoNow it is still the most popular potato, the Idaho
Russett or Burbank RussettRussett or Burbank Russett
Primary potato used in fast food french friesPrimary potato used in fast food french fries

37. Polyploidy- more than the basal complement
of chromosomes
Polyploidy is important in the
derivation of many modern crop
species
Autopolyploidy= one chromosome
set doubles, so the offspring have
twice as much of the same thing
Allopolyploidy= Doubling of two
different chromosome sets

38. Examples of Polyploids
Autopolyploids
Potato
Alfalfa
Blueberry
Allopolyploids
Bread wheat
Cotton
Tobbaco

39. Polyploidy- Plant products become larger
(to a point, anyway)
Polyploidy in castor bean

41. Bread Wheat- hexaploid (2n=6x=42)
A hybrid between emmer wheat (Triticum turgidum ssp.
dicoccum, 2n = 4x = 28) and diploid goatgrass (Aegilops
tauschii, 2n = 2x = 14), a weed in early wheat fields

43. What is this?

44. New World and Old World
Asian, African and Americas
Several species in Gossypium

45. Molecular Evidence Shows
that Modern Cotton is
Polyploid
A genome from Central
Africa
D genome from
Central/South America
AD only found in Central
America
AA genome (autopolyploid)
or
AD genome (allopolyploid)

46. Molecular/Genomics Techniques Show the
Genes that Drive Fiber Development and Quality

47. Super-Domestication
The processes that lead to dramatic increases in yield that cannot
be selected in natural environment using naturally-occurring
genetic variation. The process requires implementation of new
technology.
Example- Rice
40% of calories in China
Yields:
2.0 t/ha in 1960
3.5 t/ha in 1970
6.0 t/ha in 2005
IRRI website, Cheng et al., 2007, Annals of Botany

48. Super-Domestication
Huge increases have been made, but more will be required!
Cheng et al., 2007, Annals of Botany

49. Super-Domestication
New hybrids have been made to increase yields
Cheng et al., 2007, Annals of Botany

50. Genomics and Molecular
Biology can trace the basis
of traits changing with
domestication. These
genes can then be used for
crop improvement.
Wild species may be useful
for re-introducing traits
lost from selection.

51. One Final Thought-
Are we exploiting plants to get what we need to
survive and improve as a species…
…or are plants exploiting US to get what THEY
need to survive and improve as a species?

52. Do you want a piece of the action?
Opportunities are available!
www.hos.ufl.edu

53. Thank you!