Ever wonder why a tomato plucked from Grandma's garden tastes so much better than one foraged from a supermarket produce aisle? The answer lies not only in less-than-ideal shipping and chilling procedures, but also in the genome of the fruit itself: the natural flavor-giving chemicals have all but been bred out of most modern tomatoes. Now, horticultural scientists at the University of Florida (UF) have isolated the tomato genes responsible for flavor, and are working to reintroduce them into commercial crops.

Today's tomatoes are bred specifically to look appealing on a supermarket shelf. Since the 1940s, farmers have taken advantage of a genetic mutation that keeps their color uniformly red, but has the unwanted side effect of reducing certain sugars and chemicals that contribute to taste, resulting in a tomato that's all bark and no bite. Picking the fruit pre-ripe and then chilling them during shipping doesn't help improve their taste either – no matter how many hot baths you give them. The UF researchers set out to change this.

"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," says Harry Klee, lead author of the study. "We can make the supermarket tomato taste noticeably better."

To do so, the team analyzed the chemical and genetic makeup of close to 400 types of tomatoes, and combining that with good old-fashioned taste tests, determined which chemicals and genes are the biggest contributors to flavor. Specifically, the team looked at alleles, alternative forms of certain genes that can arise due to mutation, and will appear on the same section of chromosome as the genes they're replacing.

By analyzing which alleles control the creation of chemicals that make the fruit more flavorful, the researchers were able to separate desirable and undesirable variations. Commercial tomatoes, unsurprisingly, have fewer of the tasty-chemical-producing alleles than heirloom tomatoes.

"We wanted to identify why modern tomato varieties are deficient in flavor chemicals," says Klee. "It's because they have lost the more desirable alleles of a number of genes."

The good news is that in the not-too-distant future, the tomatoes we buy in the supermarket bins may be restored to yesteryear's height of tastiness. The researchers were able to replace the weaker alleles with more flavorful ones, with the goal of breeding better taste back into commercially-grown tomato varieties. Breeding is a slow process though, so it might take three or four years before these tastier varieties start to bear fruit.

"Around the world, the tomato is one of the most popular foods," says Gert de Couet, director of the National Science Foundation, which supported the research. "This state-of-the-art analysis sets the stage to return it to the taste of decades ago by breeding informed by molecular genetics."

The research was published in the journal Science. The team discusses the study in the video below.

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