It seems that tomatoes come in all shapes and sizes today, and a new study suggests human activity is responsible.
When people first began cultivating wild tomatoes in the Andean mountain regions of Ecuador and Northern Peru, they selected plants that produced larger fruits.
Now, thousands of years later, tomatoes on the market can weigh up to 1,000 times more than the fruits of their ancestors.
A single gene is believed to be responsible for this bulking up – and the finding could lead to even larger tomatoes in the future.
It seems that tomatoes come in all shapes and sizes today and a new study suggests human activity is responsible. Tomatoes on the market today (pictured) can weigh 1,000 times more than the fruits of their ancestors
Researchers from the University of Georgia investigated a gene they named Cell Size Regulator (CSR) that boosts fruit weight by increasing the size of the individual cells in the pericarp, the fleshy part of the tomato.
Compared to wild tomatoes, domesticated varieties carry a mutation in the CSR genes that shortens the resulting protein in their cells.
That shortening likely affects its role in regulating cell differentiation and maturation in the fruit and its vascular tissues, which deliver nutrients.
The variation originated in the cherry tomato, believed to be the original ancestor of all domesticated tomatoes.
Now, it appears in all large cultivated tomato varieties.
Dr Esther van der Knaap, who was part of the research team, said: ‘CSR is required to create the large tomatoes that are needed for the industry.
‘This is because large tomatoes critically raise the profit margins for farmers.
‘The knowledge of the gene will now open up avenues of research into how fruit size can be increased further without negatively impacting other important qualities such as disease resistance and flavour.’
Around 10,000 years ago during the Neolithic period, humans began transforming from hunter gathers to farmers.
This was accompanied by plant and animal domestication.
A single gene called CSR is believed to be responsible for this bulking up. It boosts fruit weight by increasing the size of the individual cells in the pericarp (pictured), the fleshy part of the tomato
The variation originated in the cherry tomato, believed to be the original ancestor of all domesticated tomatoes. This graph shows the role of CSR on a tomato plant’s growth
Tomatoes have had a huge increase in fruit weight as a consequence of this process.
Previous research suggested that the CSR, located at the bottom of chromosome 11, only played a small genetic contribution to tomato weight.
The finding that most cultivated tomatoes carry the shortened version of the CSR gene suggests that humans selected this genetic variation extensively.
This makes it likely that it was critical to the full domestication of tomato from its cherry tomato ancestors.