Plant Domestication Flashcards
Describe the origins of plant domestication
Began 7-10,000 years ago
- selecting desirable plants and storing them for use
Originated sub/tropical regions
- thought to have independently developed several times
Sail travel dominated 16-19thC useful as could export plants from their desired climate
Describe maize domestication
Originates mesoamerica 6,300 years ago.. ended hunter gatherer lifestyle
Most widely grown crop in world now
Major difference between progenitor and modern is seed (determined by looking at morphology 5300 yr old cob - was already half domesticated)
- progenitor = seeds shed spontaneously, 50 kernels per cob
-modern = bred to hold on to them, 1000 kernels per cob
Teosinte hypothesis of maize
Maize’s ancestor = teosinte
- smaller and fewer kernels
Mutations arose that were then selected for
- only 5 mutations needed to turn teosinte to primitive maize
Hybrid theory of maize
New studies suggest maize a hybrid of teosinte and gamma grass
Wouldn’t occur naturally =created before plants defense mechanism expressed
Performed by humans
Describe domestication of wheat
Einkorn = 2n chromosomes
Hybridised with another wild species of same number of chromosomes 11000 years ago
8000 years ago chromosomes doubled spontaneously = emmer variety
Emmer x wild goat grass hybrid formed = modern day bread wheat
How is modern day bread quality maintained?
Bakers import wheat from <100 farms and mix together
Poor crop doesn’t cause huge difference in quality
The problem with modern day rice
Lost ~10,000 genes due to mutation
- most relate to secondary metabolism and plant protection
Causes abiotic & biotic stress
What’s the affect of soil concentration on crops
Variety of crops grown on Netherlands island with high salt conc
~200/600 crops showed salt tolerance
More tolerant were sweeter e.g. tomatoes and carrots
- plant produced osmoticum in tissue as protectant = mass sugar production
