Scientists crack code of terrible tomatoes

Scientists crack code of terrible tomatoes

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A team of researchers headed by a UC Davis plant scientist claims to have discovered genes that can significantly improve the taste of tomatoes.

The U.S. tomato industry alone harvests more than 15 million tons of tomatoes each year. Many traits present in wild tomato plants and their relatives, however, have been bread out of cultivated tomatoes through generations of human-controlled conditions. Some varieties of tomatoes, known as heirloom tomatoes, are cultivated through more natural methods such as uncontrolled insect pollination. These tomatoes are valued for their sweet flavor, though they lack their red, round counterparts’ uniform appearance and tend to have inferior disease resistance and a shorter shelf life.

The UC Davis researchers collected wild tomatoes and their close relatives from a variety of locations, primarily the mountains and jungles of South American and the Galapagos Islands. They then looked for transcription factors that were linked to particular traits in tomatoes. Transcription factors are proteins that can activate or deactivate certain genes, thereby determining whether or not a tomato possesses the particular qualities encoded by that gene.

University of California Davis plant scientists, working in conjunction with researchers from Cornell University and with scientists from Spain, discovered a pair of transcription factors, GLK1 and GLK2, which are present in tomato plants that produce ripe fruit with higher-than-normal levels of sugars. These transcription factors regulate the expression of genes that control chloroplasts, the organelles within plant cells that are responsible for converting the sun’s energy into sugars. The resulting fruits are as flavorful as heirloom tomatoes yet as disease-resistant and uniform as cultivated varieties.

Flavor traits such as these can be bred into cultivated tomatoes. Jim Giovannoni, a plant molecular biologist at Cornell University, says that “nature presents numerous important genes and their variants, like uniform ripening, that breeders employ to facilitate the needs of growers, processors and consumers.”

In time, tomato breeders may introduce the genes encoding these transcription factors into some commercial tomato crops, meaning that sweeter, tastier tomatoes could one day show up on supermarket produce aisles.

Ann Powell, a UC Davis biochemist and one of the lead scientists working on this study, says that “this information about the gene responsible for the trait in wild and traditional varieties provides a strategy to recapture quality characteristics that had been unknowingly bred out of modern cultivated tomatoes,” allowing farmers access to “more varieties of tomatoes that produce well and also have desirable color and flavor traits.”

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