Keep Buying Tasteless Tomatoes? Scientists Have Found The Genetic Reason Why
Scientists compared the genes of tomatoes across the world and discovered the gene that gives them their flavour was missing from around 93 percent of modern varieties.
The study, published in the journal Nature, accumulated the genomes of 725 tomato varieties (both wild and domesticated) and then compared these to the Heinz 1706 tomato.
The Heinz 1706 is sort of like the 'mother tomato' and regarded as the genetic prototype for all modern domesticated tomatoes.
Comparing the Heinz 1706 to all of the other tomato varieties, they found that it was missing nearly 4,800 genes, including many that naturally equip tomatoes with defenses against infection from bacteria.
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Domesticated tomato varieties that you might buy at the supermarket were bred mostly for traits that would increase production value, such as size, fruit yield and shelf-life, but other important genes such as the ones that create the fruit's taste have been omitted entirely in many breeds.
The tomato taste gene is known as TomLoxC, and it was bred out of most modern domesticated tomatoes -- but it is still present in more than 90 percent of wild breeds. In order to achieve the bright red colouring, taste was compromised in the majority of supermarket tomatoes.
TomLoxC has a valuable role in the production of apocarotenoids, which are responsible for the flavour and aroma of fruits and also serve as insect attractants for breeding.
Study co-author James Giovannoni, a molecular biologist at Cornell University, said that TomLoxC influences the synthesis of "lipid-involved volatiles" --which are compounds that evaporate easily and create the signature aromas of fruits and vegetables.
Speaking to Good Food, Doctor Nabil Ahmad, a researcher in tomato genomics from Sydney University, said that the genes that these taste components of the tomato are "extremely sensitive" and any changes to the genetic makeup of the fruit can sacrifice these factors.
Ahmad said that the biggest change that has occurred in domesticated tomatoes is the insertion of the (u/u) gene into most commercial varieties -- this gene is a "uniform ripening gene" and encourages the fruit to have the recognisable red colouring.
Ahmad noted that the (u/u) gene "deactivates some of the good genes that control flavour."
However, the researchers from the Nature paper noted that the gene is slowly becoming more common in the modern market as breeders have started selecting for it again.
While it was only found in two percent of store-bought tomatoes a few years ago, it is now present in around seven percent and the gene appears to be making a comeback to satisfy consumer demands.
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