Do we need diet produce?

Is what passes for progress these days breeding for less sweet fruit? I may have missed it, but I don’t see any consumers pining for bitter apples.

Fruit varieties, in fact, have become sweeter over the years. That trend was explored in a npr.com report in 2018 called “How fruit became so sugary”

The story reflected a conversation between NPR’s Lulu Garcia-Navarro talks with food journalist Frederick Kaufman about how humans have bred fruit to be more sugary. The upshot of breeding more sugary fruit, Kaufman said then, is that we have become spoiled.

Is fruit too darn sweet? Since the 1930s, breeders have been racing to create ever-sweeter varieties, and they have succeeded. Ever heard of Cotton Candy?

“The apples you find in nature are - almost all of them are spitters,” Kaufman said in the interview. People don’t realize that everything that we’re seeing in the supermarket, they’re like superstars. They’re like supermodels and elite athletes like LeBron James. That’s what we’re looking - at the supermarket.”

Plant breeders have created supersweet fruit (and vegetables) and most of us are not complaining, though Kaufman said some dietitians believe the higher sugar content is robbing produce of a lot of its nutritional value

This week, I received a news release about scientists who have unlocked the potential to yield “diet: fruti.

From the release:

"A new study has demystified sugar distribution in plants, paving the way to create low sugar or ‘diet’ fruits. 

The study, published in Proceedings of National Academy of Sciences (PNAS), culminates seven years of research by the University of Newcastle’s Professor Yong-Ling Ruan from the School of Environmental and Life Sciences, in collaboration with peers at Northwest A&F University.

Professor Ruan said their research pinpointed the indicators that governed how much sugar is transported to the vacuole or ‘storage warehouse’ of a plant cell.

“This discovery provides new tools and directions for improving plant growth, defence and sugar levels using gene technology,” Professor Ruan said. 

“It opens the door to increase or reduce the amount of sugars in plants, helping farmers to increase the quality and yield of fresh products such as fruits and sugar cane or produce low-sugar, high sweetness fruit for a diabetic patient.”

At the cellular level in plants, sugars are delivered to the cytoplasm – a thick solution that fills each cell. The remaining sugar is then offloaded in the vacuole of the cell. 

Professor Ruan was driven by curiosity to understand exactly how sugar makes its way from the cytoplasm to the vacuole.

Understanding this link could help scientists answer long-held questions such as why fruits are so sweet yet leaves are not.

By studying apples and tomatoes, Professor Ruan said the team discovered that two different types of sugar transporters work together to transport huge amounts of sugar into vacuoles. 

“We found that glucose exported to the cytoplasm by a transporter called ERDL6 activates the expression of a major sugar influx gene. This significantly increases sugar levels in the plant cells,” Professor Ruan said. 

“Our findings represent a major advance in understanding the molecular control of sugar transport and signalling within plant cells.”

TK: From a marketing perspective, it would be great fun to tout a “diet” fruit variety to consumers, such as a Honeycrisp Lite.

The utility of the research to deliver low-sugar, high sweetness fruit to diabetics is not to be doubted, as long as we never return to the “spitters” of yesteryear.