Figure: Jim Giovannoni inspects some tomatoes in a BTI greenhouse. Photo Source: Chelsea Fausel.

Scientists led by Boyce Thompson Institute faculty (BTI) member Jim Giovannoni have discovered a gene that could help tomatoes stay firm while having the right combination of flavor and softness when eaten.

The study looked into the tomato genome for genes involved in fruit softening but not fruit ripening. The team identified a transcription factor, Solanum lycopersicum lateral organ boundaries (SlLOB1), that regulated a broad array of cell wall-related genes and fruit-softening processes. The team also searched for genes with elevated expression in the fruit's outer wall, as it was likely to express softening-specific transcription factors. In both tissues, high levels of SlLOB1 coincided with ripening.

In live tomato plants, the team found that inhibiting the expression of SlLOB1 resulted in delayed softening and firmer fruit, whereas overexpression of the gene accelerated the softening process. Inhibiting SlLOB1 had no effect on ripening, and tomatoes ripened in their normal timeframes. Lastly, they found that delayed softening induced by inhibition of SlLOB1 expression was associated with one other change. The tomato fruits were darker red in color, due to higher levels of beta-carotene and lycopene in the locule, and lycopene in the pericarp.

For more details, read the article on the BTI website.