A sweet breakthrough towards tastier and healthier fruit

Publication date
Thursday, 15 Jun 2023
Red and gren apples
Photo: James Yarema/Unsplash

A major discovery about sugars in fruit cells is a significant step towards breeding tastier and healthier fruit, according to new research led by The Australian National University (ANU).

Until now, little was known about how sugars move within cells, giving scientists and producers limited ability to influence the amount or type of sugar within a variety of fruit.

Working with apples and tomatoes, lead author Professor Yong-Ling Ruan from the ANU Research School of Biology and an international team of researchers have uncovered both how sugars are transported within plant cells and the ‘switch’ that allows them to move. "This is important because the contents of the vacuole – its sugars and acids – play a major role in how fruit tastes.”

Within plant cells, some sugars are used for energy metabolism in the cytoplasm – the gelatinous liquid responsible for maintaining a cell’s shape and function – but most are stored in the vacuole. 

“You can think of the vacuole as a cellular warehouse, where sugars and acids can be stored in high concentrations without effecting the overall health of the cell,” Professor Ruan said. 

“Just like in humans, excess sugar can be unhealthy for fruit cells, so the cell moves sugars back-and-forth from its ‘warehouse’ to maintain balance. 

“This is important because the contents of the vacuole – its sugars and acids – play a major role in how fruit tastes.” 

Using molecular and biochemical approaches, Professor Ruan and the team have discovered the key vehicle that carries sugars into the vacuole, known as the ‘tonoplast sugar transporter’ (TST). 

The team have also established the two 'switches’ that allow TSTs to move sugars into the ‘warehouse’, which the plant turns on and off as needed to maintain cellular balance. 

“We’ve revealed the molecular players that determine when, how much and potentially what kind of sugar can get into the fruit’s cellular warehouse,” Professor Ruan said. 

“This gives scientists and producers new genetic targets for breeding or engineering to increase fruit yield, quality and sweetness. 

“Previously fruit breeding has involved a lot of trial-and-error, but this discovery allows scientists to get down to a microscopic level to really understand what’s going on.” 

The work could also lead to health benefits for consumers, especially for people with specific health conditions. 

“This discovery can help us potentially develop fruit that is higher in fructose and lower in glucose, which could be beneficial for people with conditions like diabetes, for whom excess glucose can be a major issue.” 

The paper is published in Nature Plants

This article was first published at ANU Reporter.

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