Supermarket tomatoes often look a lot better than they taste. That’s because modern commercial tomatoes have gradually lost their flavor as breeders tinker with their shelf life, firmness and disease resistance.
Now it seems that we can have our tomato and eat it, too.
After a decade of research, a global team of scientists from Israel, the United States, China and Spain have identified the flavor components that contribute to the delicious taste of tomatoes, and the genes that code for the tomatoes’ flavor-enhancing chemicals.
Their study, published January 27 in the journal Science, has made it possible to produce tomatoes with their good old flavor, without sacrificing the traits that make them attractive to consumers and longer-lasting for shipment around the world.
To start the research, the Faculty of Agriculture of the Hebrew University of Jerusalem contributed 398 tomato varieties from the laboratory of Prof. Dani Zamir at the Institute of Plant Sciences and Genetics in Agriculture.
“The varieties, including modern, heirloom and wild relatives of the cultivated tomatoes, were chosen from a collection of some 8,000 tomato that we keep in a seed bank at the lab,” said Zamir’s doctoral student Itay Zemach.
Tomato fruit samples grown in Israel were sent to all participating research groups, each identifying different components: In Israel, doctoral student Josef Fisher measured and analyzed sugar content, weight, size and color.
Researchers in Spain checked for volatile compounds responsible for tomato aroma. American researchers conducted a taste test to rate the tomato varieties according to their flavor and other traits; and in China researchers sequenced and analyzed the genomes of the various varieties.
Through analysis of the chemistry of the tomatoes, researchers identified 13 compounds associated with good flavor. They determined that modern tomatoes lack sufficient sugars and volatile chemicals critical to better flavor, lost through 50 years of focus on other traits.
“The research showed a positive correlation between sugar level and taste in the tomato varieties we’ve examined. Tasters ranked varieties with high sugar levels as more delicious, and the gene screening showed that the main gene that differs in flavor-enhanced tomatoes is the one that increases sugar level,” explained Zemach.
To study how to enhance the flavor in modern tomatoes, they studied gene variants called alleles and were able to identify the locations of the “good” alleles in the tomato genome that allow the production of compounds contributing to tastier tomatoes.
After mapping genes that control synthesis of all the important chemicals, the researchers used genetic analysis to replace “bad” alleles in modern tomato varieties with the “good” alleles.
“We identified the important factors that have been lost and showed how to move them back into the modern types of tomatoes,” said Prof. Harry Klee from the University of Florida’s Institute of Food and Agricultural Sciences, who led the international study, stressing that this technique involves classical genetics, not genetic modification.
“We’re just fixing what has been damaged over the last half century to push them back to where they were a century ago, taste-wise. We can make the supermarket tomato taste noticeably better.”
Zemach said that the results of the study have already been implemented in the breeding programs of Zamir’s lab. “It’s looking possible to breed for tastier tomatoes with other excellent quality characteristics,” he said.