Israeli Scientist Makes Better Sesame Seed, Wins Award

Using ancient breeding techniques and cutting-edge genetic markers, Dr. Zvi Peleg is improving the crop yield of this exasperating plant, and its nutritional value as well.

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There are hundreds of types of sesame variants, each with different oil and nutritional properties.
There are hundreds of types of sesame variants, each with different oil and nutritional properties.Credit: Zvi Peleg
Ruth Schuster
Ruth Schuster

Sesame seeds are enormously popular but they have been a frustrating crop for farmers for thousands of years: the plant is hardy enough but its yields are low. Now a scientist at the Hebrew University of Jerusalem has developed methods to improve sesame crop yields while improving the seeds' nutritional quality too. In recognition of his work, Dr. Zvi Peleg has been awarded the Kaye Innovation Award for 2015.

Peleg's basic technique is as ancient as agriculture itself: selective breeding. You pick promising plants and cultivate and breed them while junking the inferior ones. But choosing which sesame plants to breed and which to throw out is based on cutting-edge genetic marker technology, Peleg explains to Haaretz.

Peleg's lab began with screening more than 100,000 sesame variants and is now working with some 500 strains of the seeds, which vary in color from white to brown to black. The strains differ in taste, and in the characteristics that man would like them to have beyond the basics, which include about 20 percent protein, oil and carbohydrate.

Part of the upgrade by Peleg's lab at the Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture involves increasing yield: for each plant to have more pods, in which there are more seeds. Then there's the matter of iron, zinc, calcium and other mineral content, which the team is improving through breeding, he explains.

They're also working on making the plants more suitable for mass harvesting by machine, rather than picking the pods by hand.

Sesame crop: After millennia of cultivation, crop yields and nutritional properties are being improved.Credit: Courtesy of Dr. Zvi Peleg

Enhancing desirable characteristics is being done the old-fashioned way: by selective breeding. For instance, seeds used to make oil – a practice that goes back at least 5,500 years - are being bred to increase their oil content, he says (the oil content of sesame variants can range from 34% volume to 63%). "For baking, people want bigger seeds that don't burn in baking," Peleg adds.

The lab is starting with the sweeter, "white" types of sesame seed used, for instance, in candy and tehini. "People don't want dark tehini," he explains. These seeds are being bred to have a higher sugar content.

Make no mistake, tehini (locally called "tehina") is a staple throughout much of the Middle East. Often used as a condiment, the enormously versatile thick paste is not rarely the main course itself, eaten with bread. Popular with the man in the street, tahini is also not rare in fine cuisine.

Peleg's breakthrough was creating genetic markers to identify the plants with the "right" (i.e., desirable) genes. Thus the scientists can tell as soon as a seed sprouts whether it has the right stuff, and if it does, they cultivate it, Peleg says. If it doesn't, close sesame.

"Using genetic markers makes the process of selection a lot faster," he explains. In the days of yore, farmers had to grow crops a lot longer, if not to necessarily to full to maturity, before knowing if they had desirable characteristics or not.

Aside from providing farmers with improved seeds, Peleg also has a useful suggestion: to include sesame, a summer crop that is conveniently resistant to drought, in their crop rotation. This is less about improving the sesame plant itself than improving the farmer's sustainability.

"Rotation is important for land preservation, and to sustain the efficacy of pesticides and herbicides," Peleg says, and explains.

Modern pesticides and weed killers tend to be specific to the crop, meaning that if a farmer grows wheat, for instance, he will use chemicals that kill pests of wheat. But nature fights back. The pests tend to develop immunity, forcing the farmer to find new toxins that don't kill the crops but do kill the pests.

The more crops participate in the rotation, the more types of pesticides and herbicides the farmer will likely use, and the less the chance that the local pests will develop resistance and ruin the crop, Peleg explains.

Global production of sesame is about 4.4 million tons a year, and is projected to grow by 5% to 10% a year, says Peleg. Hopefully with his innovations, crop yields will indeed improve, widening use of this nutritiously rich seed – hence the award.

The Kaye Innovation Awards have been awarded annually at the Hebrew University of Jerusalem since 1994. Isaac Kaye of England, a pharmaceutical industrialist, established the awards to encourage Hebrew University faculty and students to develop innovative methods and inventions with good commercial potential, which will benefit the university and society. Improving the crop of sesame seeds, being rich in nutrients, certainly falls within that category.