New breeding program produces purple tomatoes with high anthocyanin content

James Myers accomplished a feat no one has ever done before in 2011. The first purple tomato with the same beneficial component found in blueberries was released by a vegetable breeder at Oregon State University.

The Indigo Rose tomato, created by Myers, an OSU College of Agricultural Sciences professor, and his team over the course of ten years, has taken the market and other breeders by storm. The novelty of the tomato was well received, but the anthocyanins in the skin's health advantages were what drew people in. The public's interest in anthocyanins, the pigment that gives tomatoes their purple color and includes beneficial antioxidants, was at an all-time high.

In the past 11 years, Myers has continued to enhance his line and has added four additional purple tomatoes to the mix: Indigo Kiwi, with an improved growth habit, flavor, and resistance to leaf curl; Indigo Cherry Drops, a cherry tomato with better flavor and yield than Indigo Rose; and Indigo Pear Drops, a sweet, pear-shaped fruit. The most recent is Midnight Roma, a paste tomato that was introduced in 2021 and is utilized by professional chefs and home cooks for sauce. These may be purchased as seeds online and, in western Oregon, should be started indoors right about now. Garden centers will have some seedlings available when it's time to plant in May, maybe June this year (soil temperature should be 60-70 degrees F). However seeds could be your best option if you're looking for specific types.

There are already 50 offspring from Indigo Rose, five from OSU, and the remaining from independent breeders who used Myers's germplasm—the cells that pass on traits from generation to generation. Although purple heirloom tomatoes like Cherokee Purple, Black Krim, and Black Prince are already well-known to gardeners, the purple color in those tomatoes is really created by pheophytin, a pigment devoid of anthocyanins.

Myers and his students laboriously crossed plants that had the ability to pass on the purple gene to their progeny—often by hand from male stamen to female style. A purple tomato that was good enough to be released to breeders and home gardeners was obtained after he and his team crossed the best of the finest grown in the field for observation year after year.

Myers, who has been at OSU for 26 years and is in charge of producing a green bean variety that processors use on 80% of the land in Oregon, created the hybrid that produced Indigo Rose using genetic material from wild tomatoes kept in the germplasm collection at University of California, Davis. Two breeders went to Chile and the Galapagos Islands in the 1960s to gather the wild stock.

Breeders combined wild tomatoes with cultivated types, but research didn't advance until Carl Jones, a PhD student, started studying how tomatoes influence human health in the early 2000s, when Myers started his work. According to Myers, as Jones examined the wild species' germplasm from U.C. Davis, he discovered a hue that resembled purple but had never been described.

Efforts on developing a tomato that combined the advantages of anthocyanins for health with those of a high-quality home-grown tomato—hopefully with some disease resistance—began in earnest. After a purple tomato that was edible was created, the focus shifted to field tests. Myers and his crew planted tomato seedlings and observed their growth and production over 11 years. Every year, they cross-bred the tomatoes that had the finest purple expression. They repeatedly did it, selecting the tomatoes with the best potential. None of the tomatoes were created using GM technology.

"What would happen if we crossed the sources of purple fruit that originated from separate wild species?" was the inquiry that led to our major discovery. said Myers. "We chose tomatoes in the field based on their strong expressiveness, resistance to rot and verticillium wilt, and ability to survive longer in the field than typical tomato fruit. We located it."

The newest purple tomato variety, a genetically engineered one from Europe that the U.S. Department of Agriculture approved last year, will start to appear. In contrast, Myers' tomatoes were traditionally bred and were chosen one by one over many years. The new purple tomato, which has not yet been given a name, will be available in the United States this year but not in Europe since GMO foods are prohibited there.