A team of scientists from Cornell University and the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory has made a groundbreaking discovery, shedding light on the unexpected functions of a transport protein and its pivotal role in plant regulatory mechanisms. The study, featured in The Plant Cell earlier this year, holds the promise of addressing human mineral deficiencies by enhancing the nutritional content of edible plants.
Iron, an essential mineral for humans, plays a crucial role in various bodily functions, including being a key component of hemoglobin and supporting the immune system. Since the human body cannot produce iron, it must be regularly consumed through dietary sources, such as plants like spinach. However, strict regulatory mechanisms in plants prevent the over-accumulation of minerals, limiting their nutritional value.
The journey of this research began nearly a decade ago when scientists, including Olena Vatamaniuk, a plant biologist from Cornell, discovered that a transport protein called oligopeptide transporter 3 (OPT3) was responsible for moving iron within a model plant, Arabidopsis thaliana. Despite its name, the transporter was transporting iron instead of the oligopeptides it was initially believed to move.
In a recent study, the team aimed to delve deeper into OPT3’s role in shoot-to-root signaling, a process crucial for the plant’s response to iron status. Utilizing ultrabright X-rays, the researchers made an unexpected discovery that OPT3 not only transports iron but also copper into the phloem, a transport tissue in plants.
To conduct their analysis, the team genetically altered plants to create mutants with lower OPT3 abundance, making it lethal to remove the protein entirely. The use of confocal X-ray fluorescence imaging (C-XRF) at the National Synchrotron Light Source II (NSLS-II) provided a unique perspective on the distribution of iron and copper in mutant and unaltered plants.
The unexpected revelation that OPT3 transports both iron and copper opened new avenues of exploration. The team, through collaborative efforts at NSLS-II, uncovered a complex signaling pathway where iron and copper interact, regulating their uptake through gene expression.
While this research focused on Arabidopsis thaliana, a non-grass plant often used in research due to its rapid reproduction and mapped-out genome, the findings lay the foundation for understanding the function of this transport protein in grass plants like rice, wheat, or barley.
The collaboration between Cornell University and Brookhaven National Laboratory exemplifies the power of scientific exploration, with the researchers expressing gratitude for the support and collaboration at NSLS-II. The unexpected twists in the OPT3 story open new possibilities for addressing nutritional deficiencies and signify the importance of continued research in plant physiology.