The average grocery store tomato often presents a trade-off: you may get a nice firm tomato that is, however, watery and flavorless from its time in cold storage. On the other hand, you might spy the juiciest-looking red tomato on the shelf, only to discover when you pick it up that its soft flesh is festooned with unappetizing bruises.
Now researchers may have found a solution that tackles both these problems: they have discovered a gene that allows tomatoes to ripen but keeps their flesh firm for longer to protect against spoilage. This could be a boon not just for picky consumers, but also for tackling food waste, especially if their discovery is applied to other fruits that share the tomato’s fate.
Tomatoes are some of the most widely-consumed fruits globally, and “the most valuable fruit crop worldwide in terms of total production value,” explains James Giovannoni, a plant molecular biologist at the Boyce Thompson Institute, an independent research institute devoted to using plant sciences, and lead author on the new study. Giovannoni and his colleagues had previously studied ripening in tomatoes, a process that typically goes hand-in-hand with softening of the flesh, but this time they wanted to find out if there were any genes associated with ripening and softening whose activity they could control.
They began their research by looking for transcription factors - proteins that control gene activity - that might correspond with genes in two parts of the tomato. These were the locule, the gel-like cushion around tomato seeds where the first signs of ripening occur, and the pericarp, the fruit’s outer wall, where tangible softening occurs. Their search revealed one transcription factor called SILOB1, which was highly expressed in both these zones of the fruit, suggesting that it would play a key role in the softening processes.
By separating out the firming from the ripening process using SILOB1, the researchers were able to create tomatoes that could stay more resilient to bruising for longer, extending their shelf life, while still retaining the traits of tasty tomatoes. Indeed, the acid and sugar levels in the transgenic bred fruits showed the same profiles as in ordinary, ripened fruit, suggesting their flavors would be the same. What is more, the transgenic tomatoes may also have higher nutritional values, the researchers suggest, because they contain more of the pigments beta-carotene and lycopene, which are both antioxidants, while our bodies also convert beta-carotene into vitamin A.
Read the complete article at www.anthropocenemagazine.org.
Giovannoni et. al. “A tomato LATERAL ORGAN BOUNDARIES transcription factor, SlLOB1, predominantly regulates cell wall and softening components of ripening.” PNAS. 2021.