crop domestication 1111111111111111.pptx

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

12. T eo s in te Modern maize Domestication of Maize through Wild progenitors

13. Brassica oleracae domestication results

14. 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.

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

16. Bananas! Archeological and other evidence indicates that bananas have been cu l ti v at e d f o r o v e r 7 ye a r s . Cu l ti v ation 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)

17. 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.

18. 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.

19. Amazing variation in wild potatoes Tremendous gains from breeding