Doing the Tango has been a fruitful dance for UC Riverside and the worldwide citrus industry.
First released to growers in 2006, the UCR-developed Tango mandarin has established itself as a symbol of innovation and sustainability in the global citrus market. It has generated more than $70 million in cumulative economic value for UCR, making it one of the most successful innovations in UC history, according to University of California system data.
Marketed to consumers under brand names such as Cuties, Halos, and Tango Fruit, among others, the tasty, virtually seedless, easy-peeling fruit became a worldwide favorite — a convenient, healthy snack for consumers and a reliable, profitable crop for growers.
Now, after nearly two decades of exclusivity in the U.S., the Tango has reached a milestone. The U.S. plant patent for Tango has expired, allowing domestic growers to freely plant the variety without paying royalties.
Plant variety protection for the Tango will continue internationally, meaning royalties will still flow from international growers. But in the United States, the Tango is now open to all — from major citrus producers to home gardeners.
Its 20-year run has essentially reshaped the citrus industry.
According to the California Department of Food and Agriculture, in 2024, the Tango accounted for nearly 20,000 acres, or 32 percent of all mandarin acreage in the state — the largest share of a single mandarin variety. The U.S. Department of Agriculture estimated the total production value of mandarins in California at $855 million during the 2024–25 season, meaning Tango alone contributed about $272 million to that total.
Globally, the Tango is now grown in more than 20 countries and marketed worldwide in more than 50 countries. Just this month, a European trade association named it “Flavor of the Year” in Spain and Portugal.
“Taking into account the entire supply chain, from nurseries and farms to packers, transporters, and retailers, Tango has revolutionized the citrus industry in its 20 years of existence, generating a significant economic impact each year,” said Brian Suh, UCR’s senior executive director of technology partnerships.
The development began as an experiment by Professor Mikeal Roose and Timothy Williams at UCR’s Department of Botany and Plant Sciences with support from the California Citrus Research Board. They aimed to develop a mandarin that would remain seedless even when planted near other citrus varieties. To achieve this goal they used gamma irradiation on buds from another mandarin variety; this process sped up natural mutations that could lead to seedlessness.
The researchers grafted irradiated buds onto rootstock and observed their growth over several seasons before selecting one tree out of hundreds that met all criteria—this became known as Tango.
“Some genetic changes happen, some don’t,” Roose said. “You just have to grow the trees and wait — sometimes for years — to see what you’ve got.”
After several seasons seven trees looked promising but only two truly stood out; ultimately one was chosen because it had fewer seeds than its competitor.
That selection became what is now known as Tango.
For growers serving global markets demanding low-seeded or seedless fruits there were several advantages: sterile ovules prevent seeds from forming while sterile pollen means nearby varieties are unaffected by cross-pollination with Tangos; these traits reduced costs associated with preventing pollination such as using nets or isolating crops.
“It’s very easy to grow in the nursery,” Roose said. “It works well on main rootstocks we use grows vigorously produces heavy yields… it’s a dream variety for growers.”
For consumers its appeal includes ease-of-peeling bright flavor no need for refrigeration firm skin long shelf life suitability for shipping late-season availability extending mandarin season by two months.
“It had all qualities you want… easy peel rich color great flavor very low seeded even when grown near other varieties,” Roose said. “That combination is very rare.”
Williams expressed pride: “You spend years working with hundreds of trees then one day there it is—the one that checks all boxes… When you see it grocery stores lunchboxes around world that’s pretty good feeling.”
Tango continues UC Riverside’s legacy since opening its Citrus Experiment Station on campus in 1907—introducing over forty new citrus varieties including Oroblanco grapefruit grown globally as specialty crop—and housing collections like Givaudan Citrus Variety Collection which preserves biodiversity with thousands of trees representing over one thousand varieties worldwide.
“When you look at Tango’s success it’s gratifying—but it also reminds you we’re just one chapter in much longer story…” Williams said.
“The challenges facing citrus today—new diseases climate sustainability—are different… but mission is same: keep California citrus viable valuable accessible well into future.”
