Scientists Discover Genetic Keys to Evolution of Multicellularity

Researchers at Nagoya University in Japan have made significant strides in understanding the genetic mechanisms that enable organisms to alternate between single-cell and multicellular life forms. This discovery, detailed in a study published in Nature, sheds light on how multicellular organisms like plants and animals may have evolved from their single-celled ancestors.

Under the leadership of Professor Gohta Goshima at the Sugashima Marine Biological Laboratory, the team focused on the black marine yeast Hortaea werneckii. Their research revealed that this organism can adapt its form based on nutrient availability. When nutrients are plentiful, H. werneckii cells multiply and stay connected, forming multicellular structures. Conversely, when nutrients are scarce, these cells divide and live independently, allowing them to move through water in search of more favorable conditions.

This ability to transition between different life forms appears to provide a survival advantage in the ocean’s unpredictable environment. The researchers isolated mutants that were unable to switch forms and identified ten crucial genes involved in this process. Specifically, they found that a protein known as Myb1 acts as a key regulatory switch. High levels of Myb1 promote budding and separation, while its degradation in nutrient-rich environments encourages the formation of multicellular bodies.

Interestingly, some of the identified genes were already known for their role in fungal spore production. The study suggests that H. werneckii has repurposed these genes to facilitate its unique switching capability, highlighting a possible evolutionary strategy for developing new traits.

Multicellularity and Environmental Adaptation

The team also explored multicellular-prone strains of H. werneckii found on the surfaces of marine animals such as sponges and corals, known for their nutrient-rich environments due to symbiotic bacteria. The researchers hypothesize that this multicellular formation aids the yeast in anchoring itself to nutrient-rich surfaces, thus preventing it from being swept away by currents.

Laboratory experiments supported this hypothesis. When both unicellular and multicellular strains were subjected to simulated water flow, the multicellular forms remained attached, while the unicellular cells were easily displaced. This observation indicates that multicellularity may confer advantages in stable, nutrient-rich habitats.

In addition to identifying the genetic basis for switching in H. werneckii, the study compared related yeast species. It revealed that the genetic pathways for switching are not universally conserved. For instance, a related yeast species, Neodothiora pruni, also exhibits switching abilities but relies on different genetic mechanisms. This variation underscores the complexity of evolutionary adaptations among similar organisms.

Implications for Future Research

Professor Goshima expressed a keen interest in further exploring the evolutionary diversity observed in these yeast species. He noted, “What we achieved was controlling unicellularity and simple multicellularity, but the next obvious step is whether simple multicellularity becomes more complex multicellularity.” The simplicity of genetic mutations that can eliminate or restore cellular flexibility indicates that the transition between unicellular and multicellular forms may have been a recurring theme throughout evolutionary history.

The findings from Nagoya University position H. werneckii as a valuable model for scientists investigating the origins of multicellular life. The ability to switch between life forms may have served as an important evolutionary stepping stone before the development of permanently multicellular organisms, as highlighted by Professor Goshima’s research.

As this area of study progresses, it promises to deepen our understanding of the evolutionary processes that led to the complex life forms we see today. The publication of these findings in March 2026 marks a notable milestone in the field of evolutionary biology.