Posted on 04/20/2006 1:33:04 PM PDT by blam
Week of April 15, 2006; Vol. 169, No. 15 , p. 237
Early farmers took time to tame wheat
Bruce Bower
Domesticated varieties of wheat emerged gradually in the prehistoric Near East over a roughly 3,000-year span, a new investigation suggests.
CULTIVATED FINDS. Microscopic analysis of wheat grains such as these from a 6,500-year-old Syrian site revealed clues to plant domestication in prehistoric times. Willcox/CNRS
Ken-ichi Tanno of the Research Institute for Humanity and Nature in Kyoto, Japan, and George Willcox of the National Center for Scientific Research in Berrias, France, examined 804 wheat-ear remnants recovered at four ancient villages in southeastern Turkey and northern Syria.
Wild and domesticated ears of wheat shatter at maturity in distinctive ways, so microscopic study can distinguish the two forms.
No signs of domesticated wheat appeared at the oldest Near Eastern site, which was initially inhabited about 10,200 years ago, Tanno and Willcox report in the March 31 Science. A 9,250-year-old village yielded a small amount of the cultivated cereal. Progressively larger amounts of domesticated wheat turned up at two younger sites, one dating to 7,500 years ago and the other to 6,500 years ago.
The researchers suspect that as wheat domestication slowly expanded, some Near Eastern farmers nevertheless continued to tend and harvest wild wheat.
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I thought I read all about that in "Guns, Germs and Steel". Is this supposed to be news?
I guess the real trick was teaching them to "Stay", and waking up in the morning to see if the whole field was still there, or had wandered off in the nighttime, leaving a dustbowl.
Intriguing. One might expect a more rapid dissemination once domestication was achieved.
That was a period when wheatherders had an advantage because they could follow the wheat and bring it back to the farm.
Ancient genetic tricks shape up wheat.
I recall this being presented in a PBS nature or history show many, many years ago and the implications were that man didn't domesticate wheat, wheat domesticated man.
Wow!
Thanks for the link, and...wow!
Where'd we be without that first hybridization?
Ancient genetic tricks shape up wheat
Turning back the evolutionary clock offers better crops for dry regions.
by Tom Simonite
news@nature.com
By re-enacting an evolutionary event that happened to wheat thousands of years ago, researchers are producing new plant varieties that could save lives in regions where drought causes food shortages.
Bread wheat (Triticum aestivum), a staple food for millions of people around the world, is the product of two rare genetic events that happened during the Stone Age in a region of the Middle East known as the 'fertile crescent'.
Two different species can't usually breed to produce hybrid offspring, because their chromosomes don't match and can't pair properly during the process that produces sex cells such as eggs and sperm. But sometimes a genetic blip can produce sex cells with double the normal number of chromosomes, side-stepping the problem. If two sex cells of this type combine, a whole new fertile species with double the number of chromosomes is produced.
Doubling up
This rare 'duplication followed by fertilization' event has happened twice in the history of modern, common wheat. Around 30,000 years ago, a wild wheat (Triticum monococcum) hybridized with a species of goat grass (Aegilops speltoides) to generate primitive wheat called emmer, which had four sets of chromosomes. Then about 9,000 years ago, emmer wheat grown south of the Caspian Sea crossed with another wild goat grass (Aegilops tauschii) to produce a plant with six sets of chromosomes.
This hybrid had larger seeds than its ancestors, thanks to the bonus chromosomes, and so became a popular breed for early farmers. The descendents of these plants now cover more farmland globally than any other crop, filling more than 500 million acres worldwide.
But this genetic triumph came with a downside: the wheat was so popular that no one farmed anything else, leading to a very low genetic diversity and limiting the options for plant breeders hoping to develop varieties resistant to drought or pests. To counter this, researchers at the International Maize and Wheat Improvement Center (CIMMYT) in Mexico have developed a way to top up bread wheat's shallow gene pool.
Something old, something new
"We've been re-enacting in the lab what took place in nature nine thousand years ago," says Richard Trethowan, a specialist in wheat breeding at CIMMYT. Researchers collected wild goat grass from the Middle East and crossed it with modern versions of emmer wheat to create bread wheat all over again. They used chemicals in the lab to induce the rare chromosome doubling that makes hybrids fertile.
The technique helps to introduce new genes in the same way as genetic engineering, but without requiring the researchers to know which genes they are on the lookout for beforehand.
The new bread wheats are not themselves suitable for farming, since most of the new hybrids have qualities that are more advantageous to grasses than to wheat. "They’re ugly things," says Trethowan. But he adds that it is easy to use traditional breeding methods to get the few useful genes into common bread wheat strains.
Food for thought
The genetic input has allowed improvements to wheat's drought resistance, for example. One wheat strain developed by the team produces between 20 and 40% more grain under dry conditions than traditional bread wheat, the researchers told an international symposium of plant breeders in December.
CIMMYT has sent seeds produced by the research out to centres worldwide for local testing and development, and initial results have been promising. Farmers in Ecuador are racing to switch to one test strain that significantly outperforms the established local wheat, Trethowan says. He predicts that in five or six years time the new genes found by reinventing wheat will be dramatically improving yields everywhere. "We're on the brink of quite a big genetic revolution for wheat breeding," says Trethowan.
John Snape, a cereal geneticist at the John Innes Centre, Norwich, UK, adds that rich countries will probably benefit from this revolution too. "It is likely that climates in Europe will get hotter and drier thanks to climate change, and this will put new stresses on crops," he says. One fungal wheat disease, Fusarium head blight, has already started to plague European fields thanks to warmer, more humid summers, he points out. "Being able to reach out into wild species for new genes to tackle these problems is very valuable," he says.
This is silly, every right thinking person knows that the world is only 6000 years old.
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