Anyone who has eaten newly ripened and freshly picked garden tomatoes, especially those grown in warmer climes, will be able to appreciate criticism of the flavour of the typical tomato bought from a supermarket. The supply chain from field to supermarket has a major impact.
Tomatoes, as with other fruit and vegetables, are harvested before they are fully ripe so that they have a shelf life that includes transportation time. But there is another big influence on taste. Commercial varieties have been bred for qualities such as shelf life, pest resistance, yield and stress tolerance.
Of course, for the producers of the 182 million tonnes of tomatoes eaten every year, amounting to a £42 billion industry, these qualities are important. They are all influenced by particular genes and modern, commercial varieties for mass production have been bred for those genes. But the concentration on those genes have meant others have been largely ignored, including those that influence flavour.
Garden-grown tomatoes, as well as not having to survive days to possibly weeks between being picked and eaten, are often closer to ‘heirloom’ varieties. Which are in turn genetically closer to the original wild varieties modern commercial tomatoes are descended from.
Now new gene mapping research and techniques exploring the tomato ‘pan-genome’, that covers the genes present in 725 domesticated and wild varieties, has uncovered the gene thought to have the most influence on flavour – TomLoxC. Or rather, a now rare version of the TomLoxC gene.
The discovery was made after researchers mapped almost 5000 genes found across tomato varieties. The version of TomLoxC they concluded makes tomatoes tastier was found in only 2% of domesticated tomato varieties. While there are hundreds of different varieties of cultivated tomatoes, they have a narrow genetic base as a result of selective breeding over the years. That appears to have all but wiped the TomLoxC version found to influence appealing flavour. In contrast, the gene was present in over 91% of the wild tomato varieties whose genomes were mapped.
The result of the research is that breeders of domestic tomato varieties have now started selecting for TomLoxC. It’s now present in 7% of shop-sold tomato varieties with the gene’s influence also growing in strength. Which means that within another several years we can expect a big jump in the quality of flavour of the tomatoes sold in supermarkets. The research was published in Nature Genetics.
The latest genome mapping techniques are giving us a far more detailed understanding of what individual genes influence than ever before. That should mean that the genes that influence the flavour of other fruit and vegetable varieties will one day be discovered and new varieties bred for flavour rather than commercial considerations such as shelf life and pest resistance. Everything bought from your local Tesco might eventually be as rich in flavour as, or at least much closer to, produce picked from a garden in Southern Italy and taken straight into the kitchen. Now that’s an upside to gene mapping technology most of us will be happy to cheer!