Scientists solve long-standing mystery of amino acid transport in plants
The discovery of how plants move life’s building blocks has unlocked new potential for developing nutrient-rich crops and ensuring food security.
An international research team led by Heinrich Heine University Düsseldorf, with contributions from Michigan State University’s Peter K. Lundquist, decoded the mechanism by which plant chloroplasts export essential amino acids. This breakthrough not only resolves a decades-old mystery in plant biology but also has far-reaching implications for improving the nutritional quality of crops.
The team’s new study, published in Nature Plants, identifies a class of previously unknown transport proteins called RETICULATA1 (RE1), which enable the exchange of key amino acids within plant cells.
Unlike humans, plants have the ability to synthesize all 20 proteinogenic amino acids, which is why plant-based foods are an essential part of a nutritious diet. Nine of these, including key building blocks like lysine and arginine, are produced only in plastids, such as chloroplasts.
Until now, it was unknown how these amino acids could pass through the chloroplast membrane.
“The molecular function of RE1 has been a mystery for decades, even though mutations in this gene cause conspicuous leaf shapes in the model plant Arabidopsis thaliana,” explained Andreas P.M. Weber, Heinrich Heine University Düsseldorf professor and corresponding author on the study. “Our research shows that RE1 is a specialized transporter for basic amino acids.”
The team demonstrated that plants lacking RE1 develop a characteristic net-like leaf pattern, accumulate lower levels of basic amino acids, and fail to maintain balanced amino acid pools between plastids and the rest of the cell. Plants entirely without RE1 and its closest homologue, RER1, are unviable, underscoring the critical, overlapping roles plastidial amino acid transporters play in metabolism, development and nutrient allocation.
RE1 belongs to a previously uncharacterized family of proteins found only in organisms with plastids, such as plants and algae. By uncovering its function, the team has provided the first explanation of this protein family’s role in a transport system unique to plants.
Lundquist, faculty member of MSU’s Plant Resilience Institute and co-author on the study, contributed critical expertise in plastid biology.
“By understanding this transport system, we can start to envision ways to improve the nutritional quality of crops and strengthen their resilience without disrupting other cellular processes,” Lundquist said. “This kind of discovery highlights the importance of fundamental plant science in addressing future agricultural challenges.”
By uncovering the mystery of how plants transport essential amino acids from plastids, scientists have provided a foundation for developing more nutritious and resilient crops, ensuring global food security in the face of climate change and growing agricultural demands.