PLANT ORIGIN AND
DOMESTICATION
Origin of Cultivated Plants
 Methods of Plant Domestication
 Examples of Crop Improvement
 Germplasm Discovery and Preservation

Origin of Cultivated Crops
Vavilov was a pioneer thinker in the
concept of centers of origin. He
postulated that most of the cultivated
plants came from eight independent
centers.
a. other scientists dispute his theory
b. major importance is that these are
centers of genetic diversity.
See Text Note
Methods of Plant Domestication
Some methods that have been used to domesticate
or “tame” plants:
Vegetative or asexual methods – one outstanding
grapevine amongst many others was selected
and became the parent source when cuttings
were taken from the superior original vine
See Text Note
a. maintaining this with subsequent selections
will insure further improvement
b. this is a form of unknowing artificial selection
How is this different from what Darwin called
natural selection?
Methods of Plant Domestication
Seed or sexual methods – act of choosing
superior seed from each harvest and saving it
to plant the next crop:
a. large and vigorous seed found to give
better germination and greater yield…after
several generations of this selection pressure
the crop is greatly improved
b. seed shattering or scattering is not
desirable in domesticated plants and can be
minimalized by saving and replanting seeds
that remain on plant.
Improvement in Specific Crops
Wheat
Early improvements were probably
spontaneous due to natural
chromosome increase and improved
fertility.
a. migrated from Middle East to Spain to
the New World (Americas)
Improvement in Specific Crops
(Wheat, continued)
b. Mennonite settlers came from Russia to
Kansas and introduced hard red wheats that
became foundation of Great Plains bread
wheat industry
c. hundreds of specific cultivars developed:
Specific for:
1. Climate
2. High yield
3. Milling properties
4. Disease resistance – i.e. stem rust
Improvement in Specific Crops
(Wheat, continued)
d. Dr. Norman Borlaug *
1. Noble Prize Winning Agronomist
2. Short dwarf type wheats
3. Able to take fertilizer not lodge
4. Adapted them to India and Pakistan
5. Became grain exporters by 1970’s
* His work laid the foundation for what
became known as “The Green Revolution”
Plant Improvement Programs
Principles of Darwinian Evolution: (Charles
Darwin)
 Variation exists in plant and animal
populations
 Environmental stress favors certain
individuals
 Favored, surviving individuals leave desired
characteristics in offspring, changes the
population
 Abundance of good traits is increased in
each generation but variation persists
Plant Improvement Programs
Darwin had no theory about how the
expression of these traits was
controlled, so man was not influential in
the evolutionary process other than
basic selection already described.
Plant Improvement Programs
Principles of Genetic Mode of Plant Inheritance:
(Gregor Mendel)

Mendel’s discoveries explained Darwin’s
observations

Inheritance of traits is under control of genes

Inheritance patterns are mathematically
predictable

Science of genetics and modern plant and
animal breeding was begun
USDA has established breeding or plant
improvement programs at land grant
universities in the U.S.
Germplasm Discovery and
Maintenance
History of plant explorers is interesting
reading. (from the text book)
Preservation of plant diversity is crucial.
U.S. Congress passed Endangered
Species Act in 1973.
1. Smithsonian Institute directed to
identify endangered plant species and
find ways to save them
Germplasm Discovery and
Maintenance
U.S. has National Plant Germplasm
System in place
 Example: USDA Seed Storage Lab
cold storage
180,000 seed lots
preserved forever?
Germplasm Discovery and
Maintenance

Goals and activities
– introduction of new and foreign plant
materials
– maintenance of germplasm on hand
– evaluation of genetic resources
– distribution of germplasm to scientists
Search for a new and alternative crops in U.S.
World fed by about 20 crops. Disease or
minor environment changes could be
disasterous
Impromptu Review Quiz-5 points
1.
Organisms that are self-sufficient in nature are said
to be ___________
2.
Match the following lists:
primary producer___
primary consumer___
secondary consumer___
3.
a.
b.
c.
grass pasture
humans
beef cattle
Which of the following would not be attributed to
bacteria:
a.
nitrogen fixation
b.
sugar production for plants
c.
act as scavengers
d.
fermentation-preservation
4.
_______(name) postulated that diverse plant
populations came from_______ __ ________
5.
Plant domestication can come from ________
or ___________ methods.