Commercial growing has eventually changed the genetic makeup of the tomato, making the once-sweet fruit relatively flavorless. Now, researchers have identified the flavor-enhancing genes that the tomato lost which could give growers a roadmap to make tomatoes flavorful again.

Determining The Most Flavorful Of Tomato Varieties

In a new study published in the journal Science on Jan. 26, Harry Klee, from the University of Florida, and colleagues analyzed the genetic codes of 398 varieties of tomatoes. The researchers then chose 160 samples of tomato that roughly represent a hundred varieties and grew these in the lab.

Once the fruits were ripe, the tomatoes were given to a panel consists of 100 people who tasted and rated the tomatoes based on the taste. The feedback helped scientists determine which of the tomatoes varieties people liked the most.

The researchers then used gas chromatography to sort out the molecules of the tomato samples yielding a list of chemicals and their concentrations for each sample of the tomatoes.

Klee and colleagues then zeroed in on chemical compounds called volatiles, which are released when the fruit is chewed and trigger a response in the olfactory system, that contributes to the overall taste sensation.

By comparing the panel's tomato preference to the chemical profiles of the fruit samples, the researchers were able to come up with a list of 13 chemical compounds that are strongly associated with the flavors that people tend to enjoy.

The researchers were also able to identify the acids, sugars, and aroma compounds that can make tomatoes flavorful. The researchers were thus able to create a genetic roadmap that can help growers produce tasty tomatoes.

"Whole-genome sequencing and a genome-wide association study permitted identification of genetic loci that affect most of the target flavor chemicals, including sugars, acids, and volatiles," the researchers wrote in their study.

"Together, these results provide an understanding of the flavor deficiencies in modern commercial varieties and the information necessary for the recovery of good flavor through molecular breeding."

Making Once- Sweet Tomatoes Flavorful Again

Commercially sold tomatoes are not as flavorful as the heirloom varieties that are characterized by sweet and richer flavors. Klee said that by crossbreeding commercial tomato crops and heirloom varieties over multiple generations, tomato growers can gradually produce large and plump red tomatoes that are not only disease resistant but taste pretty good as well. The researcher said that the process may only take a few years.

"A breeder can now simultaneously select for hundreds of these genetic markers to rapidly select new plants with as many of the desirable traits as possible," said Adrian Hegeman, from the University of Minnesota, who was not part of the study. "This will make it easier to cross two different tomato varieties and test the progeny from that cross at very early stages of growth to get rid of plants that lack key gene linked traits."

Although crossbreeding could lead to tastier tomatoes that are sold in the mass market, researchers cautioned that modifying the genes may also mean the fruit would have shorter shelf life.

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