University of California, Riverside (UCR) citrus researcher Mikeal Roose is among 23 honorees across the University of California (UC) campuses who recently received UC Regents Innovation Awards. Roose is credited with co-developing the seedless Tango mandarin. The awards recognize UC faculty members whose research has real-world impact.
Roose was among 11 honored in the Distinguished Lifetime Achievement Award category for “innovations that have led to long-term positive impacts on the lives of others and inspiring UC inventors and entrepreneurs.”
Roose, who joined UCR in 1982, is now an emeritus faculty member. He is a citrus geneticist and past chair of the Department of Botany and Plant Sciences. In 2006, he received the Award of Excellence for Exceptional Service to the California Citrus Industry.
Roose used citrus genetics to develop several new mandarin varieties, including the virtually seedless Tango, an easy-to-peel fruit often found under the name Wonderful Halos, Cuties or Delites. His research also targets huanglongbing (citrus greening), a major threat to the citrus industry worldwide.
Roose co-developed the Tango with research associate Timothy Williams, an effort that began in the 1990s to develop a mandarin that would remain seedless regardless of what citrus was grown in proximity.
“It had all the qualities you want in a mandarin — easy to peel, rich color, great flavor and very low seeded even when grown near other varieties,” Roose said. “That combination is very rare.”
The Tango mandarin has generated more than $70 million for UCR, making it among the most successful innovations in University of California history. According to state figures, in 2024, the Tango accounted for nearly 20,000 acres — or 32% — of all mandarin acreage in California, the largest share of a single mandarin variety.
Recently, Tango’s U.S. plant patent expired, allowing domestic growers to plant the variety without paying royalties.
Source: UCR
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