In the world of agriculture, where the search for innovations that can increase yields and ensure food security is constant, scientists have turned their attention to a group of elements whose potential has been shrouded in mystery for decades. These are the lanthanides, a class of rare earth metals that in some parts of the world, particularly in China, have long been added to fertilizers to promote plant growth. Despite their widespread use on millions of hectares of arable land, the fundamental mechanisms of their effect on plants have remained largely unknown. The lack of understanding of how plants absorb these elements and how they affect key biological processes, such as photosynthesis, has been a significant obstacle to their optimized and conscious use. However, a recent scientific discovery by scientists from the prestigious Massachusetts Institute of Technology (MIT) sheds a completely new light on this issue, opening the door to new strategies for strengthening crop resilience and improving seedling growth.

Unraveling the molecular interaction: Lanthanides at the heart of chlorophyll

A team of researchers, led by associate professor Benedetto Marelli and postdoctoral fellow Giorgio Rizzo, conducted an exhaustive study whose results were published in the prestigious scientific journal Journal of the American Chemical Society. Their work provides the first concrete evidence of how lanthanides function within plant cells. The key discovery lies in their interaction with chlorophyll, the pigment essential for photosynthesis – the process by which plants convert sunlight into chemical energy. At the very center of the chlorophyll molecule is a magnesium ion, the loss of which leads to the degradation of the pigment and a reduction in its ability to absorb light. The MIT scientists discovered that lanthanides can occupy the vacant magnesium site. This process, which they called "re-greening," allows chlorophyll molecules to partially restore their optical properties and stability. It was found that lanthanides form so-called "sandwich complexes" with chlorophyll, where the lanthanide ion binds to the porphyrin ring, replacing magnesium and thereby strengthening the pigment's structure. This finding is of fundamental importance as it clarifies why and how these elements can positively affect plant health at the molecular level.

An unexpected superpower: Protection from harmful UV radiation

One of the most significant and completely unexpected results of this study is the finding that lanthanides can significantly increase plant resistance to ultraviolet (UV) radiation. In an era of climate change, where agricultural crops are increasingly exposed to extreme weather conditions, including longer periods of intense solar radiation, this discovery has enormous potential. Chlorophyll is an extremely sensitive pigment that, outside of the protected cellular structure, degrades rapidly. However, the research team showed that chlorophyll, when complexed with a lanthanide at its center, becomes surprisingly stable, even after extraction from plant cells. This increased stability provides plants with a kind of natural shield against UV stress. Today's methods for protecting crops from UV radiation often rely on the application of agrochemicals that are sprayed on the leaves. Such products can be toxic, contribute to microplastic pollution, and require multiple applications during the season. Treatment with lanthanides offers a complementary, and potentially more environmentally friendly, approach, reducing the need for conventional protective agents.

From seed to harvest: A new, more efficient application method

A long-standing challenge in the use of lanthanides has been achieving the right balance – low concentrations stimulate growth, while high ones can be toxic. The problem is further complicated by the fact that it is not known exactly how plants absorb these elements from the soil. The MIT researchers bypassed this problem by applying an innovative seed treatment technology they had previously developed. By applying a single, extremely small nanoscale dose of lanthanides directly to the seed, they achieved significant positive effects. This method ensures that the beneficial elements are available to the plant from the very beginning of its development. Analyses have shown that lanthanides mainly accumulate in the plant's roots, but a smaller, yet significant amount is also transported to the leaves. There, it is incorporated into newly formed chlorophyll molecules, thereby directly contributing to the plant's health and resilience. The effectiveness of this approach has been confirmed on a range of key agricultural crops, including chickpeas, barley, corn, and soy, indicating the broad applicability of this technology.

The economic and ecological potential of a discarded metal

The study also has important implications for the global rare earth metals market. The researchers found that the larger elements from the lanthanide group, such as lanthanum (La), are more effective at strengthening chlorophyll pigments. Lanthanum is, ironically, considered a low-value byproduct in the rare earth mining process and often represents a burden on the supply chain because it needs to be separated from more sought-after and expensive elements like neodymium or dysprosium. Creating a new, massive demand for lanthanum in agriculture could fundamentally change the economics of rare earth mining. This would not only improve the stability of the entire supply chain but also encourage the recycling and utilization of elements that were previously considered less useful. "This study shows what we could do with these lower-value metals," points out Professor Marelli, emphasizing that the research focused precisely on lanthanum as the most abundant and cheapest lanthanide ion.

The future of research and application in agriculture

This research represents only the first, but a crucial, step towards a full understanding and conscious use of lanthanides in agricultural production. The MIT team plans to expand its research to field trials and greenhouse studies to test the effects on UV resistance in different crop species and in real agricultural conditions. The long-term goal is to develop precise guidelines for farmers that will allow them to harness the benefits of these elements in the most effective and safest way, primarily through advanced seed treatment methods. In addition to agriculture, the team intends to investigate how lanthanides interact with other biological molecules, including proteins in the human body, which opens up the possibility for completely new applications in biomedicine and other fields. As Giorgio Rizzo emphasizes, lanthanides are already used in agronomy, but this study provides the scientific basis for their smarter application and the introduction of new, superior application methods.