The Pistachio Man

Dana Bauer
January 01, 2002
pistachios in bowl

"Persian pistachios are perfect, the best in the world," says Omid Harandi, "It's true," he says, a grin pushing up the handles of his dark mustache. "It's not just me who says that. Everyone who studies pistachio knows."

The Queen of Sheba recognized perfection. She so loved the pistachio that she demanded all her lands' production for herself and her court. According to Muslim legend, the pistachio was one of the foods brought to Earth by Adam.

Harandi, a doctoral student in Penn State's Intercollege Program in Genetics, is one of a long line of Persian pistachio producers. His family plants and produces pistachios in the Kerman Province of Iran, where William E. Whitehouse, an American plant scientist, first gathered pistachio seeds to bring back to the Unites States in 1926. Today, almost all pistachio grown in the United States—the world's second biggest producer after Iran—are of the Kerman variety, known for its large nuts and widely split shells.

But the Kerman is only one of many varieties of the species Pistacia vera, the only pistachio species that produces edible nuts large enough to be commercially acceptable. The diversity of pistachio found in Iran, whose ancient name is Persia, is unsurpassed in the world. The pistachio was first cultivated there over 3,000 years ago, and today more than 50 cultivated varieties of pistachio and an uncountable number of wild ones thrive in the arid and semi-arid Middle Eastern climate. Pistachios are Iran's biggest hard currency earner after oil and textiles.

Despite its diversity and rich history, says Harandi, "very little is known about the genetics of the Persian pistachio." As a graduate student at Azad University of Karaz in Iran, he set out to uncover the history —genetically speaking—of the nut with which he was raised.

Harandi gathered cultivated and wild pistachio plants from around the country. He traveled 7,500 miles, tromping through orchards and forests, deserts and mountainous regions. "It was difficult. I had to collect fresh leaves and keep them under ice until I could get them back to the freezer in Tehran."

At the National Research Center for Genetic Engineering and Biotechnology in Tehran, where Harandi was a research associate, Harandi evaluated the chromosome numbers of different species of pistachio. He also examined proteins called isozymes in the fresh leaves to determine how the plants were related. Isozymes can serve as molecular markers that are linked to specific traits—resistance to fungi, for example. Comparing those markers can help to determine differences and similarities among species and varieties. For example, Pistacia atlantica is very different from the other two pistachio species that occur naturally in Iran: Pistacia khinjuk and Pistacia vera, which are very primitive (or ancient) species. Harandi also found great differences between the cultivated and wild varieties of P. vera, such as kalehghoghi (one of the best cultivars for pistachio production), and wild sarakhs from the Sarakhs Forest in northeastern Iran.

In 2000, Harandi won a Vavilov-Frankel Fellowship —awarded annually by the International Plant Genetic Resources Institute (IPGRI) to young researchers from developing countries—to continue his research in the United States. He chose Penn State as his host university for the project. Majid Foolad, associate professor of plant genetics, served as the project adviser.

In Foolad's lab, Harandi extracted DNA from his dried pistachio leaves (flown in from Iran) and used DNA markers to "fingerprint" the genotypes of the different pistachio plants. DNA markers are small sequences of DNA linked to regions in a plant's chromosome that can be responsible for or associated with a specific trait. "Different plants have genes that allow them to handle different stressors," Harandi explains. "Usually wild plants have resistance to pests like insects and fungi. They're very tolerant to environmental stresses like cold and drought. They can survive in many bad conditions because they have those genes." Like the isozyme markers, DNA markers allow Harandi to chart these differences among plants.

"The major object is to identify what we have," he says, extending his hands as if to grasp Iran's bounty of pistachios. "This basic information—about the germplasm, about the genetic relationships—could be used for other projects."

These might include genetic modification of existing cultivars to develop a cultivar that is resistant to fungi or drought, crucial for the California pistachio industry.

Also, Harandi adds, if we understand what we have, we can preserve the biodiversity of the pistachio, both for genetic and cultural reasons.

"The pistachio is very ancient, and it has many stories," he says. Legend has it that lovers met in orchards to hear the pistachios crack open on moonlit nights—a sign of good fortune.

"Everyone knows the pistachio," says Harandi, "and when you mention it, almost everyone says, 'Oh! I love the pistachio!'"

Omid Harandi is a doctoral student in the Intercollege Graduate Degree Program in Genetics; ouf100@psu.edu. His adviser is Majid Foolad, Ph.D., associate professor of plant genetics, College of Agricultural Sciences, 217 Tyson Bldg., University Park, PA 16802; 814-865-5408; mrf5@psu.edu. Funding for this project was provided by the International Plant Genetics Resources Institute.

Last Updated January 01, 2002