Food scientists are reporting a discovery that could lead to new tomato varieties with vintage heirloom flavor and greater health benefits.
An international research team, headed by University of California-Davis plant scientists, said the finding could lead to improvements in the estimated 15 million tons of tomatoes sold each year in the U.S. – giving them both better taste and higher levels of the beneficial cancer-fighting nutrient lycopene.
The research team’s findings, reported in the journal Science, are based on extensive analysis of a collection of rare and wild species of tomatoes collected by UC scientists since in the 1950s. By studying the genes that influence the development of the best-tasting and most healthful varieties, the researchers identified several proteins – known as GLK1 and GLK2 – that regulate genes and affect color, quality and nutrient levels.
The UC-Davis researchers found tomatoes that are unusually dark green before they ripen naturally have higher levels of such proteins. That gives them increased levels of sugars – and better taste – and much higher levels of the health-promoting compound lycopene than are typically found in mass-produced tomatoes sold in the U.S.
"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," said lead researcher Ann Powell, a biochemist in UC Davis' Department of Plant Sciences.
"Now that we know that some of the qualities that people value in heirloom tomatoes can be made available in other types of tomatoes, farmers can have access to more varieties of tomatoes that produce well and also have desirable color and flavor traits."
For decades, researchers noted, plant breeders in the tomato industry have selected varieties that are uniformly light green before they ripen, so they can be harvested at the same time. But this characteristic produces a reduction in sugars that compromises the flavor of the fruit as well as other undesirable affects.
To reach its conclusions, Powell's UC-Davis research spent two summers screening and examining tomato plants for genetic factors that influence fruit color, flavor and quality.
"Nature presents numerous important genes and their variants, like uniform ripening, that breeders employ to facilitate the needs of growers, processors and consumers," said Jim Giovannoni, a U.S. Department of Agriculture plant molecular biologist at Cornell University. "Understanding the genes responsible for these characteristics facilitates the challenging process of breeding crops that meet the needs of all components of the food-supply chain."
Funding for the study was provided, in part, by the USDA.