Crop DomesticationCrop Domestication

From Wild Weeds to High Quality From Wild Weeds to High Quality FoodFood

Kevin M. FoltaKevin M. FoltaDepartment of Horticultural SciencesDepartment of Horticultural Sciences

Plant Molecular and Cellular Biology ProgramPlant Molecular and Cellular Biology Program University of FloridaUniversity of Floridakfolta@ifas.ufl.edukfolta@ifas.ufl.edu

What is “Natural” when we talk about food?

What is Domestication?

Def- is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control.

Agriculture Accelerated the Human Condition

From Kates, 1994

My Definition

Domestication leads to the production of plant parts that are more beneficial to humans than the parts produced by wild antecedents.

Me, 2010

What are traits that early farmers may have selected?

decreased plant stature, loss of photoperiod sensitivity, loss of seed dormancy, and most notably, a dramatic increase in the abundance, length, and quality of seed epidermal fiber

http://www.eeob.iastate.edu/faculty/WendelJ/fiberevolution.htm

What are some traits engineered intodomesticated 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 and/or ripening

Synchronous germination

More desirable food forms (loss of protective tissues or seeds)

Types of Domestication

Incidental- Didn’t happen on purpose. Hunter/gatherers droppedseeds, 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.

Agriculture- Human intervention in crop husbandry. Cultivation. Selection.

Where did Domestication Start?

Grains of rye with domestic traits recovered from 11,000BC

The bottle gourd (Lagenaria siceraria) was 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.

Most of them are aliens!

(at least) Three major crops have genetic roots in Mexico

Corn domestication started at least 10,000 years ago in MexicoOldest archeological evidence in Tehuacan in Central HighlandsRadiated rapidly throughout MesoamericaMain subsistence of Mayans and Azetcs

Teosinte

Modern maize

Brassica oleracae

Floral reversion in ag-1 mutant backgrounds

Parcy F et al. Development 2002;129:2519-2527

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.

What was the driving force behind barley domestication?

Sumerian tablet, 4000 BC

What is this?

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 bananasspread into the range of wild bananas.

Domesticated (genome = AA)Wild (genome = BB)

Modern banana = AAB and ABB triploids! (that’s why they are infertile)

What is this one?

What is this one?

Origins of Cultivated Strawberry

Fragaria chiloensisFragaria virginiana

1714

1534, 1588

8x = 56

1759 “Fragaria ananassa Duchesne”

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.

Lycopersicon cheesmanii

Lycopersicon parviflorum

High Vitamin C, tiny fruits

High Vitamin C, tiny fruits, drought tolerantTiny fruits, drought tolerant

Lycopersicon pennellii

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.

What are these?

Amazing variation in wild potatoes

Tremendous gains from breeding

Lake Titicaca is the place where humans first likely cultivated potatoes. This is on the border of Bolivia and Peru.

~7000 years ago.

Chuño – smashed potatoes with feet, frozen and dried.

B MYSPUDBOY

PotatoesCultivated 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.

Breakthrough Gains by Luther Burbank in 1870’sBreakthrough Gains by Luther Burbank in 1870’s

Planted 23 seedlings from a strange ‘Early Rose’ Planted 23 seedlings from a strange ‘Early Rose’ potato plant that set seedspotato plant that set seeds

Noted one that made 2-3x more tubers than othersNoted one that made 2-3x more tubers than others

Sold the rights for $150Sold the rights for $150

Now it is still the most popular potato, the Idaho Now it is still the most popular potato, the Idaho Russett or Burbank RussettRussett or Burbank Russett

Primary potato used in fast food french friesPrimary potato used in fast food french fries

Polyploidy- more than the basal complement of chromosomes

Polyploidy is important in the derivation of many modern crop species

Autopolyploidy= one chromosome set doubles, so the offspring have twice as much of the same thing

Allopolyploidy= Doubling of two different chromosome sets

Examples of Polyploids

Autopolyploids

Potato

Alfalfa

Blueberry

Allopolyploids

Bread wheat

Cotton

Tobbaco

Polyploidy- Plant products become larger(to a point, anyway)

Polyploidy in castor bean

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

What is this?

New World and Old World

Asian, African and Americas

Several species in Gossypium

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)

Molecular/Genomics Techniques Show the Genes that Drive Fiber Development and Quality

Super-Domestication

The processes that lead to dramatic increases in yield that cannot be selected in natural environment using naturally-occurring genetic variation. The process requires implementation of new technology.

Example- Rice40% of calories in China

Yields:

2.0 t/ha in 19603.5 t/ha in 19706.0 t/ha in 2005

IRRI website, Cheng et al., 2007, Annals of Botany

Super-Domestication

Huge increases have been made, but more will be required!

Cheng et al., 2007, Annals of Botany

Super-Domestication

New hybrids have been made to increase yields

Cheng et al., 2007, Annals of Botany

Genomics and MolecularBiology can trace the basis of traits changing with domestication. These genes can then be used for crop improvement.

Wild species may be useful for re-introducing traits lost from selection.

One Final Thought-

Are we exploiting plants to get what we need to survive and improve as a species…

…or are plants exploiting US to get what THEY need to survive and improve as a species?

Do you want a piece of the action?

Opportunities are available! www.hos.ufl.edu

Thank you!