Genetic fix can make mass-produced tomatoes taste great again

Not as tasty as they used to be

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By Bob Holmes

Mass-produced tomatoes are infamous for their bland, disappointing flavour. It’s even worse if you refrigerate them.

But there’s hope on the horizon: geneticists have learned what went wrong, and how to make commercial tomatoes taste almost as good as their home-grown counterparts. Best of all, the same approach can be used to improve the flavour of many other fruits and vegetables.

Harry Klee of the University of Florida, Gainesville, and his colleagues asked volunteers to rate the flavour of 398 different tomato cultivars, including commercial varieties, heirloom tomatoes and wild strains. Using a gas chromatograph to measure the chemical constituents of each cultivar, they identified the specific odour molecules, known as volatiles, that contribute to desirable tomato flavour.

The group then searched through the entire tomato genome to find the gene variants, or alleles, that determine whether each variety produces high or low amounts of these molecules.

Hidden pleasures

Every modern variety contained gene variants that produce fewer of the many important flavour molecules, the team found. “You can go through the list and say oh, look, here’s a gene that affects the volatiles – and oh, look, the modern varieties have the less superior allele,” says Klee.

The superior alleles were probably lost accidentally as breeders focused on improving yield, he says. Because each individual allele makes only a subtle difference to flavour, the loss of one or two at a time would pass unnoticed – but over time, the accumulating losses add up to a big decrease in flavour.

The superior alleles are still there in heirloom varieties, so breeders should be able to reintroduce them to the commercial varieties you might pick up in a supermarket. Klee is now in the process of doing exactly that in his laboratory, and expects to have results within a year or so.

Strawberry surprise

The good news is that this shouldn’t reduce crop yield much, because the volatile chemicals are present at such tiny concentrations, he says.

Klee has used the same approach to identify the molecules and genes responsible for flavour in strawberries and blueberries, and he expects that the technique will work in other crops, too. Indeed, Carol Wagstaff of the University of Reading, UK, and her colleagues are now taking the same path to breeding tastier rocket, also known as arugula.

But tastier varieties won’t amount to much unless growers — who care more about yield and disease resistance — can be persuaded to plant them. That will only happen if enough consumers insist on more flavourful food, says Wagstaff.

A complicating factor is that most fruits and vegetables aren’t identified by variety in the supermarket. Until they are – as has now started to happen for a few crops including some tomatoes, apples and potatoes – consumers have no way to demand better flavour.

Journal reference: Science, DOI: 10.1126/science.aal1556

Read more: The flavour factory: Hijacking our senses to tailor tastes