Concept of Crop domestication

1. Sub.:- Fundamentals of Plant Breeding
Course No. :- APB- 5211
Credit hours:- 3(2+1)
Lec. Topic :- Domestication of Crop plants
Presentedby:-
Lt. Roshan Parihar, Asstt. Professor
Deptt. of Genetics & Plant Breeding
Indira Gandhi Krishi Vishwavidyalaya
Raipur, C.G.
BTC College of Agriculture & Research Station
,Sarkanda, Bilaspur,(CG)-495001

2. Domestication is the process of adapting
wild plants and animals for human use, for
food, work, clothing, medicine, and many
other uses.
Domesticated species are not wild.
Individuals that exhibit desirable traits
are selected to be bred, and these desirable
traits are then passed along to future
generations.
Domestication (ग्राम्यन)

3. A plant is said to be domesticated when its native
characteristics are altered such that it cannot grow and
reproduce without human intervention.
Domestication is thought to be the result of the
development of a symbiotic relationship between the
plants and humans, called co-evolution, because plants
and human behaviors evolve to suit one another.
In the simplest form of co-evolution, a human harvests
a given plant selectively, based on the preferred
characteristics, such as the largest fruits, and uses the
seeds from the largest fruits to plant the next year.

4.  Plant domestication is the genetic modification of a
wild species to create a new form of a plant altered
to meet human needs (Doebley et al., 2006)
or
 Plant domestication is the process by which
humans actively interfere with and direct crop
evolution.
or
 Plant domestication is the continuum of increasing
codependence between plants and people.
Definitions of Plant domestication

5. •Renowned Swiss botanist, son of a famous botanist, Augustin-
Pyramus de Candolle (1778-1841), born in Paris took over his father's
botanic garden with a vast collection.
•de Candolle write a massive tome on plant geography that assumed
the derivation of each species from a specially created individual.
•Alphonse de Candolle, in his 1882 book Origine de Plantes Cultivées,
was among the first to indicate regions where plant domestication
may have taken place: China, Southwest Asia including Egypt, and
Tropical Asia.
ALPHONSE DE CANDOLLE
NIKOLAI IVANOVIC VAVILOV (1887-1943)
Renowned Russian botanist proposed theories of plant genetic
diversity. Vavilov also developed a theory of the historical
centers of origin of cultivated plants. , "The Law of Homologous
Series in Variation,1922. Through His Global Expeditions He Had
Collected Over 36,000 accessions of wheat, Over 10,000 of
maize, Over 23,000 of legumes, Around 18,000 of vegetables,
Over 12,000 of fruit and small fruit crops Over 23,000 of
Pioneer scientists

6. Examples:- Cattle in Africa, goats in the Middle East, and
llamas in South America.
While Wolves were the first animal to be domesticated,
sometimes between 33,000 and 11,000 years ago.
Grains of rye with domestic traits recovered from
11,000BC.
The bottle gourd (Lagenaria siceraria) was recovered
from 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, soybeans, etc.
 Strawberry domesticated by non-native people about 250
years ago.
Where did Domestication Start?

7. First stage the pre-adapted wild plants with weedy
tendencies and large reserves of food began to colonize the
open ground around man's house. Probably seeds were dropped
accidentally near the house from the natural habitats.
Second stage Seeds were regularly harvested as food from
the open ground around man's house, and fenced to protect
them from domesticated cattle and other herbivores. At this
stage, the man also select mutants for increased yields,
palatability and other desirable traits.
Third stage Man learnt sowing of seeds at the right time with
understanding of plant for required husbandry upto
harvesting.
Stages of domestication.

8. 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.
Types of Domestication

9. Domestication syndrome: It is the subset of traits
that collectively form the morphological and
physiological differences between crops and wild
progenitors.
These distinct suites of traits later termed the
Domestication syndrome (DS) would likely be selected
for the initial stages of domestication (Harlan, 1973)
What is Domestication syndrome ?
A variety of Morphological changes .
A variety of physiological changes .

10. What are some Domestication syndrome 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,ripening,germination.
More desirable food forms (loss of protective tissues or
seeds).

11. Super-domestication:- The processes that lead to a
domesticate with dramatically increased yield that could not
be selected in natural environments without new technologies.
•The array of engineering tech. facilitates the barriers to
gene exchange to be overcome and have lead to super-
domesticates with dramatically increased yields, resistant to
biotic and abiotic stresses and new characters for market
place eg. Flavr savr tomato with delayed ripening gene
action.
•Hybrid rice can be considered as a super domesticated
crop.
•Conversion of a crop from C3 to C4 photosynthesis would
certainly be a super-domesticate.
Super-domestication

12. The Near
East
Sub-
Saharan
Africa
China India
Meso-
America
South
America
Northeast
America
Ethiopia
Central
Asia
Papua
New
Guinea
Emmer African rice Rice Pigeon pea Maize Potato Sunflower Tef Onion Yam
wheat Sorghum Adzuki bean Guar Common bean Amaranth Chenopod Noog (niger) Garlic Banana
Barley Pearl millet Buckwheat Urd bean Cacao Quinoa Squash Enset Carrot Taro
Pea Cowpea Soybean Mungbean Avocado Peanut Apple
Lentil Yam Litchi Sesame Sweet pepper Cassava Peach
Chickpea Okra Ginger Mango Chilli pepper Apricot
Bitter vetch Ragi Tepary bean Pear
Flax Lima bean Pistachio
Olive Vanilla
Fig Anona
Date-palm Tomato
Grape
Table 1 Partial list of major crop plants arranged based on their putative domestication
centers following a modified Vavilovian scheme (1951) and updated based on Doebley et
al. (2006)

13. •Scope for yield stability of a crop rather than yield
maximization on average fields.
•Scope for alternative land use (eg. Legumes and cereals
have a contrasting response to the seasonal rain profiles and
therefore when cereals provide poor yields, the grain
legumes are likely to give relatively high yields and vice
versa).
•Scope for nutritional perspective, a mixed diet of both
cereals and grain legumes is a more sustainable strategy
than reliance on a single cereal or legume. (e.g., soybean and
rice in China, maize, and common bean in Meso-America,
sorghum, and cowpea in sub-Saharan Africa).
Scope of Plant Domestication

14. Domesticated plants Wild progenitors
More seed retention . More seed retention .
Low seed shattering. High seed shattering.
High level germination. Low level germination.
Fast and upward growth habit. Low and shruby growth habit.
Bigger size of flowers and fruits. Smaller size of flowers and fruits.
Variable coloration . Variable coloration.
High edibility with low toxicity. Low edibility with potent toxins.
Less tolerant to Biotic and Abiotic
stresses.
High tolerant to Biotic and Abiotic
stresses.
Domesticated plants Vs. Wild progenitors

15. •Reduction in genetic diversity at domestication related genes and
tightly linked loci in domesticated crops relative to the wild progenitors
•This reduction has two causes:
Genetic bottleneck:-The bottleneck effect is an
extreme example of genetic drift that happens when the size of
a population is severely reduced. Events like directional selection can
decimate a population, killing most imtermediate indviduals and leaving
behind a small, random assortment of survivors.
Selective sweep :- In genetics, a selective sweep is the process through
which a new beneficial mutation that increases its frequency and becomes
fixed (i.e., reaches a frequency of 1) in the population leads to the
reduction or elimination of genetic variation among nucleotide sequences
that are near the mutation.
Effects of selection during domestication

17. Three major crops have genetic roots in Mexico

19. Teosinte
Modern maize
Domestication of Maize through Wild progenitors

20. 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

21. Brassica oleracae domestication results

22. 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)
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.

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

24. Tetraploid Banana (Seeded) Triploid Banana (unseeded)

25. 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)

26. What is this one?
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.

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

28. 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.
Comparisons to wild
relatives brings new
opportunities for changes
in flavors, disease
resistance, etc.

29. Amazing variation
in wild potatoes
Tremendous gains
from breeding

30. 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.
Lake Titicaca is the place
where humans first likely
cultivated potatoes. This is on
the border of Bolivia and Peru.
~7000 years ago.

31. 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
Autopolyploids
Potato
Alfalfa
Blueberry
Allopolyploids
Bread wheat
Cotton
Tobbaco

32. 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

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

34. 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)
Evolution of Gossypium through Domestication

35. Thanks