Transcript 09. Agriculture

Agriculture
Read “how to tame a wild plant”,
for next time. Quiz on this
Tuesday.
Read Ch. 10, 11, 15
Human Nutritional Needs
• Carbohydrates (simple, complex, fiber)
• Amino acids for proteins
– Essential (9 of 20); plant proteins “incomplete”
• Lipids (fats, oils, sterols, phospholipids)
– At least 3 essential; unsaturated
• Vitamins (13 needed; 8-9 from plants: e.g., A, E,
K, C, several “Bs”)
• Minerals (17 or more; major & trace; Ca,Fe,I
deficiency common)
• *secondary compounds; e.g., medicinals
Figure 10-2
Origins of agriculture
• Ca. 10-15,000 years ago
• Arose in different areas
• Utilized pre-adapted wild plants
– (e.g., wheat, corn, pea, barley, lentel, rice)
• Allowed for settlements and increases in
rates of “advancement” in civilization
Fig. 43.3a
Fig. 43.3b
Origin of Corn
Arose from wild teosinte in southern Mexico ca.
9000 years ago
Only a few (5) mutations required for this
(e.g., loss of fruitcase, silica & lignin accumulation,
branching pattern = 2 genes)
Humans selected for desirable mutations of
propogated teosinte (= artificial selection)
All modern corn from a founding bottleneck of 10
generations and 20 plants from a single
domestication event of subspecies parviglumis
From 6000 to 3000 y.a., selection increased cob size
By 4400 y.a., a homogeneous superior widely-used
crop corn existed
Corn continued
• Now we have sweet, feed, sugar & oil corn
• Genetically modified corn (e.g., to resist
pests)
• Development of acid-tolerant cultivars and
corn with higher lysine & tryptophan
Modifications leading to different
vegetables
Quiz on “how to tame a plant”
1) What plant, mentioned by the author, is
conspicuous in its absence from the list of
domesticated plants?
2) List three desirable traits of a plant that
would make it a good candidate for
domestication.