crop domestication

1. Domestication of plant
History and Process

2. The domestication of plants is a significant milestone in human
history, marking the transition from hunter-gatherer societies to
settled agricultural communities. This process began around 12,000
years ago, during the Neolithic Revolution, and profoundly influenced
the development of human civilization.

3. • 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

4. 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.

5.  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

6. History:
• Origins: Plant domestication likely began in multiple regions around the world
independently, including the Fertile Crescent (modern-day Middle East),
Mesoamerica, South America, China, and other areas where wild plants were
abundant.
• Neolithic Revolution: This period, approximately 10,000 BCE to 2,000 BCE, saw the
transition from nomadic hunter-gatherer lifestyles to settled agricultural
communities. It was during this time that humans began deliberately cultivating and
domesticating plants.
• Selective Breeding: Early farmers selected plants with desirable traits, such as larger
seeds, higher yield, easier harvesting, and resistance to pests and diseases. Over
generations, continuous cultivation of these selected plants led to genetic changes
that made them more suitable for human use.
• Spread of Agriculture: As agriculture developed, it spread from its origins to other
parts of the world, often through migration, trade, and cultural exchange. Different
regions domesticated different plant species based on local environmental conditions
and societal needs.

7. Process:
• Identification of Wild Plants: Early humans identified wild plants with edible parts or other
desirable characteristics. These plants typically had seeds or fruits that could be harvested and
consumed.
• Propagation: Humans began deliberately planting and tending to these wild plants near their
settlements. Initially, this involved simple methods such as scattering seeds or transplanting
seedlings.
• Selective Cultivation: Farmers selected plants with desirable traits and saved their seeds for
replanting in subsequent growing seasons. This process, known as selective cultivation or artificial
selection, gradually favored the proliferation of plants with traits beneficial to humans.
• Genetic Changes: Over time, repeated cycles of planting, harvesting, and selection led to genetic
changes in the cultivated plants. Traits such as larger seeds, increased yield, loss of seed dispersal
mechanisms, and changes in growth habits emerged through this process.
• Human Intervention: As agricultural practices became more sophisticated, humans intervened
more actively in the breeding process. This included techniques such as controlled pollination,
hybridization, and eventually, modern genetic engineering.
• Domestication Syndrome: Many domesticated plants exhibit common characteristics collectively
known as "domestication syndrome." These include changes in seed size, loss of natural seed
dispersal mechanisms, reduction of chemical defenses, and alterations in growth habits.

8. Domestication syndrome: It is the subset of traits that
collectively form the morphological and physiological
differences between crops and wild progenitors.
What is Domestication
syndrome ?
A variety of Morphological changes .
A variety of physiological changes .

9. Domestication syndrome refers to a set of characteristic traits that tend to emerge in
plants as a result of the domestication process. These traits represent common
changes observed across various domesticated plant species and are often distinct
from their wild ancestors. The syndrome typically includes several key features:
• Reduced Seed Dispersal Mechanisms: Wild plants often have evolved
mechanisms to disperse their seeds over a wide area, ensuring the survival of their
species. However, in domesticated plants, these mechanisms are often lost or
significantly reduced. This loss of seed dispersal mechanisms makes it easier for
humans to harvest seeds and fruits from domesticated plants.
• Increased Seed Size: Domesticated plants frequently have larger seeds compared
to their wild counterparts. This trait is favored by human selection because larger
seeds often mean more nutrition or a higher yield per plant, making them more
desirable for cultivation.
• Loss of Natural Defenses: Wild plants typically possess chemical compounds or
physical structures that deter herbivores and pests. However, during the
domestication process, these defensive mechanisms are often reduced or lost
altogether. Domesticated plants may become more vulnerable to pests and
diseases without human intervention.

10. • Changes in Growth Habit: Domesticated plants often exhibit alterations in their growth
habits compared to wild plants. For example, they may have a more compact or bushy
growth form, making them easier to cultivate and harvest. Changes in branching patterns,
leaf morphology, and overall plant architecture are common in domesticated plants.
• Reduced Bitterness or Toxicity: Many wild plants contain bitter or toxic compounds as a
defense mechanism against herbivory. However, during domestication, humans tend to
select for plants with reduced levels of bitterness or toxicity, making them more palatable
and suitable for human consumption.
• Loss of Photoperiod Sensitivity: Wild plants often rely on environmental cues such as day
length (photoperiod) to regulate their flowering and reproductive cycles. Domesticated
plants may lose this sensitivity to photoperiod, allowing them to flower and produce seeds
under a wider range of conditions, which can be advantageous for cultivation in different
climates.
• Dependence on Human Care: Perhaps the most significant aspect of domestication
syndrome is the increased reliance of domesticated plants on human care for survival and
reproduction. Domesticated plants have evolved to thrive in human-managed
environments, where they receive water, nutrients, protection from pests, and other forms
of care from human cultivators.

11. Domesticated plants Wild progenitors
More seed retention . Less 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

13. Teosinte
Modern maize
Domestication of Maize through Wild progenitors

15. Brassica oleracae domestication results

16. Barle
y
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.

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

18. 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)

19. 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.

20. 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.

21. Amazing variation
in wild potatoes
Tremendous gains
from breeding