Scientists at the University of Nebraska-Lincoln have mapped a previously unknown region inside chloroplasts—the tiny cellular powerhouses where plants convert sunlight into food—revealing what amounts to nature's assembly line for the machinery of photosynthesis. The discovery, published in Nature Communications, identifies a specialized area where photosynthetic membranes are built, repaired, and maintained, answering a question that has puzzled researchers for decades: How do plants actually construct these intricate structures they depend on to survive?
The work represents a fundamental advance in understanding photosynthesis, the process by which plants turn light energy into chemical energy. While scientists have long known the mechanics of photosynthesis itself, the physical membranes on which it occurs are far more mysterious. These membranes must be continually assembled, remodeled, and repaired as plants grow and respond to stress—heat, drought, and intense sunlight all damage them, reducing crop yields worldwide. Understanding how plants build and maintain these structures could unlock new strategies for improving agricultural resilience and even inspire the design of artificial solar-energy systems.
The journey to this discovery was led by Rebecca Roston, an associate professor in the Center for Plant Innovation and the Department of Biochemistry, who had nursed the ambition since her time as a graduate student. "The idea that we knew where every atom of a photosystem was, but had no idea how its structures were actually built, fascinated me," Roston reflected. "I dreamed that if I ever had my own lab, I would try to figure it out."
The path forward, however, required the persistence of an entire team. Graduate student Evan LaBrant began by screening dozens of proteins to locate where they existed within chloroplasts, using fluorescent tagging to mark their positions. Despite facing multiple personal tragedies that nearly drove him from graduate school, LaBrant returned to develop the core strategy. His trainee, Joslin Ishimwe, employed a machine-learning technique to analyze thousands of microscopy images LaBrant had created, identifying several key protein candidates that appeared in specialized regions.
To prove these proteins actually built membranes, researcher Cailin Smith conducted rigorous experiments. Working with expert microscopist Bara Altartouri, Smith demonstrated that when certain proteins—named TVPFP and PMFP—were missing, the plant's photosynthetic membranes became disorganized. In tvpfp mutants, membrane contact regions extended abnormally, while pmfp mutants showed reduced density at contact sites. Blinded undergraduate researchers Lauren Litterer and Allan Tullis helped quantify the data.
The final breakthrough came through proteomic analysis—a comprehensive survey of all proteins in the sample. Alondra Torres-Genera and proteomic expert Michael Naldrett profiled the proteins alongside Fan Huang's parallel analyses, revealing what the team calls a "light thylakoid" intermediate-density fraction. This fraction was enriched in lipid transport, lipid metabolism, and other processes tied to membrane remodeling, containing multiple proteins related to known membrane contact-site factors. The discovery supports the idea that chloroplasts contain specialized regions dedicated to membrane maintenance.
The implications ripple outward in two directions. For agriculture, this understanding could help identify new ways to strengthen crops against environmental stress. For renewable energy, photosynthetic membranes represent one of nature's most efficient solar-energy conversion systems—clarifying how plants build and maintain them could inform the design of bio-inspired technologies for solar-to-fuel and solar-to-electricity applications. Both Evan LaBrant and Cailin Smith successfully defended their dissertations following the study's completion.