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A cross section of the surface of a ripe tomato fruit, with its thick cuticle ‘skin’ stained in red.

It is one of life’s little disappointments: that piece of fruit so fresh in the grocery store turns soft and withered in only a few days, and an anticipated snack ends up as garbage instead.

Multiply that scenario millions of times and add with it all the fruit grocers discard before it’s ever sold, and those many minor disappointments suddenly become a very real and expensive waste of food and resources.

Previous research by plant scientists identified the hydrophobic cellular surface layer known as the cuticle as a prime factor influencing water retention in fleshy fruits. Now, a new College of Agriculture and Life Sciences project plans to study the structure of the cuticle at a resolution never before realized, using the tomato as a model. The three-year project will identify the specific cuticle components and the structural and regulatory pathways that mediate their biosynthesis and deposition, answering fundamental questions that may ultimately improve quality and extend the shelf life of harvested fruit.

Little is known about how cuticle structure affects its function despite its importance as a barrier to fruit desiccation and the over-softening, tissue collapse and microbial infection that results. The collection of waxes covering and embedded in the layer are thought to be primarily responsible for water retention and critical for preserving fruit quality, said Jocelyn Rose, a professor of plant biology and director of Cornell’s Institute of Biotechnology.  

“There are many fundamental aspects of the cuticle and its architecture that are still really mysterious,” said Rose, who will lead the project funded by a $500,000 U.S. Department of Agriculture grant. “What those waxes contribute, why you need so many, what each one does, how they interact, where they are localized: these are all things we don’t know. It’s an incredibly complex structure.”

Rose said the cuticle can be thought of as an outer framework made up of cutin, a polymer he likened to a sponge covered and permeated with wax. The collection of waxes vary at stages of development and in response to environmental factors, such as drought. Learning the composition of those waxes, when and where they accumulate, and the genetic mechanisms responsible for each can inform the scientific understanding of fruit physiology and desiccation resistance, Rose said, and the findings could have enormous economic value to the agriculture industry.

“The shelf life of fruits and fruit quality are very closely linked with their ability to retain water, and that desiccation and spoilage is a major deterrent for shipping,” he said. “It’s a major bottleneck for exporting and transporting fruits, storing them and getting them to market.”

Rose said the project will use a broad range of analytical approaches to give a detailed understanding of wax diversity, compositional dynamics and functional significance during development and in response to drought stress in domesticated tomato and two wild relatives.

Matt Hayes is managing editor and social media officer for the College of Agriculture and Life Sciences.