The bitter taste of olive oil and olives is one of their most prized qualities. Behind this tree lies a mystery that science is only beginning to unravel, and it could have implications for both improving crops and combating metabolic diseases.
A new study has identified the biochemical pathway that allows the olive tree —Olea europaea— to produce oleuropein, a molecule responsible for the fruit’s flavor and which has been associated with antioxidant properties and potential cardiovascular benefits.
“This work largely stems from frustration,” says Carlos Rodríguez, a researcher at the Integrative Biology Unit of the Institute for Obesity Research at Tecnológico de Monterrey and author of the article.
Like the scientific community that studies plants, Rodríguez assumed that the olive used similar mechanisms to produce similar compounds, but the experiments did not work.
To solve this, him and his team compared different plants that produce similar compounds, such as ash and jasmine. They looked at which genes were active in different tissues—roots, leaves, and fruits—but produced related molecules.
“We Know Very Little About Plants”
This approach allowed the complete route to be reconstructed, closing a knowledge gap that had persisted for decades. “It may not seem like it, but we know very little about plants, even the ones we eat,” says Rodríguez.
They cross-referenced large volumes of genomic data and narrowed down thousands of potential candidates to a few hundred. Then, they selected a group of enzymes and tested them experimentally.
Thus, they discovered that the route the plant follows to produce oleuropein did not depend on the enzymes that the scientific community had assumed —cytochrome P450 type— but on the family of 2-oxoglutarate-dependent dioxygenases.
The research is the result of a multinational collaboration, with researchers from Italy, China and Germany, and institutions such as the Max Planck Institute for Chemical Ecology and the Institute of Biosciences and Bioresources.
Applications on the Understanding of Plant Chemistry
The discovery opens up various possibilities. One is to improve the selection process for producers, enhancing the flavor of olive oil and olives through genetics.
Currently, producers select varieties with desired characteristics—such as color, flavor, or shape—and crossbreed them to obtain the desired product. However, this process can take years.
By knowing the genes associated with these characteristics, it is possible to predict which plants will produce olives with the best sensory profile.
“I can limit it to a smaller number of plants, by doing a genetic screening,” says the researcher.
Oleuropein and its derivatives could also be produced on a large scale, which have been studied for their potential effects against cardiovascular and metabolic diseases, such as obesity.
Obtaining these molecules in large quantities is complicated, as it requires significant volumes of the fruit. In the future, this information could be used to transfer the genes to microorganisms such as yeast to produce them efficiently and study their therapeutic potential.
Towards the Design of Functional Foods
This connects to a global challenge: obesity. Beyond calories or traditional nutrients, food contains a vast array of molecules that could influence metabolism. Understanding how these molecules are produced opens the door to designing functional foods that help regulate metabolic processes or even satiety.
The olive tree and the way in which they discovered the metabolic pathway then becomes a model for exploring the therapeutic and nutritional potential of the plants we eat.
In Mexico, this methodology and knowledge could be transferred to local crops, identifying beneficial compounds in traditional foods.
“Meat has similar molecules, but plants have a great chemical diversity,” says Rodríguez. “In my group, we want to study that diversity and how plants generate it.”
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