Domestication of Crop plants

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 Presented by:- 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 forages. 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 . T he 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, soy beans , 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. A gr i c u l t ur e- H u m a n i n t e r v e n t i o n i n c r o p h u s b a n dr y .C u lt i v a t i o n . 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 ba rriers 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

16. Three major crops have genetic roots in Mexico

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

18. 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

19. Brassica oleracae domestication results

20. 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.

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

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

23. 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)

24. 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.

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

26. 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.

27. Amazing variation in wild potatoes Tremendous gains from breeding

28. 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 .

29. Polyploidy- more than the basal complement of chromosomes Polyploidy is important in the derivation of many modern crop species Autopolyploidy = one c hromosome set doubles, so the offspring have twice as much of the same thing Allopolyploidy = Doubling of two different chromosome sets Autopolyploids Potato Alfalfa Bl ueb erry Allopolyploids Bread wheat Cotton Tobbaco

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

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

32. 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

33. Thanks