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Mikeal Roose

Chair and Professor of Genetics & Geneticist
Mikeal Roose
Protecting California’s Commercial Citrus Industry
As a member of the Agriculture Experiment Station, Mikeal Roose’s responsibility is to conduct research that improves the sustainability of the agriculture industry in California and to provide consumers with products that improve their health. By developing fruit such as the Tango that is flavorful, attractive and has few seeds, the goal is to encourage greater consumption of these fruits, ultimately benefiting the health of consumers.

Areas of Expertise


Q: How was the Tango Mandarin developed? What is significant about Tango?
The Tango was developed starting in 1995 by mutation breeding, in which we induced mutations in an existing variety – in this case the W. Murcott Mandarin, which is a great fruit but has too many seeds when subjected to cross pollination. We exposed little bud sticks with a piece of citrus tissue to radiation similar to a dental x-ray in order to cause mutations in the buds, which were then grafted to root stalks. From the trees that grew, we found a few that contained very few seeds, which is the goal trait we were working towards.

Tango is a very unusual mandarin with desirable characteristics, correcting the major fault of too many seeds in the parent variety. It is a strongly flavored mandarin with a rich, sweet flavor, it is very easy to peel, has an attractive deep orange rind color, and, most importantly, Tango doesn’t produce many seeds – on average we get about one seed out of every five fruit.

Q: How do your new varieties reach the marketplace?
The process for reaching marketing involves compiling documentation about the fruit’s performance and its consistency over years and a variety of locations, which is presented to the university that appoints a committee to evaluate our data. At the same time, if we feel the fruit has market value, a patent application is submitted. Once the decision has been made to release the variety, we provide clean bud wood to commercial nurseries that begin the process of growing trees for growers and consumers.

Q: How can we find the Tango at the grocery store?
You may have had one and not known it! Companies don’t necessarily label the fruit as a Tango, as it is marketed by multiple companies and growers using their own brand names. One of the biggest is Cutie Mandarins – late in the season, you may find Tango or its parent fruit the W. Murcott in these boxes.

Q: What’s the history of citrus studies at UC Riverside?
The ancestry of the UCR campus traces back to the Citrus Experiment Station which opened in 1907 with faculty working on citrus and other subtropical crops for about 50 years before the campus was developed. When the campus was founded, citrus research was folded into the university activities and citrus research has remained strong here ever since.

In addition, the Citrus Variety Collection at UCR is an incredibly valuable university resource consisting of two trees each of more than 1,000 different citrus types. Used extensively to solve citrus disease problems and improve commercial varieties, the collection is one of the world’s premier citrus germplasm collections.

Q: What does Living the Promise mean to you?
To me, Living the Promise means conducting research that benefits consumers and the citrus industry in California, and also training students and others that come to work with me, providing guidance and inspiration so they can reach their own goals.

Q: Why is UC Riverside a great place to do research?
I’ve been at UC Riverside for more than 30 years and I think the greatest benefit of doing research here is the people. The staff at agricultural operations maintains trees for us, the genomics institute provides us with services to do genetics and genomic analysis, we have great support from administrative staff, and I’ve been able to assemble an outstanding team to do research. All of these people coming together really enable us to achieve success.

Mikeal Roose “Tango is a very unusual mandarin with desirable characteristics, correcting the major fault of too many seeds in the parent variety.”

—Mikeal Roose
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