Marine Yeast Study Unlocks Genetic Secrets of Multicellularity

Scientists at Nagoya University in Japan have made significant strides in understanding the genetic mechanisms that enable an organism to transition between single-celled and multicellular forms. Their research, published in the journal Nature on March 15, 2026, focuses on the black marine yeast Hortaea werneckii and offers valuable insights into the evolution of multicellular life from simple ancestors.

The study, led by Professor Gohta Goshima at Nagoya University’s Sugashima Marine Biological Laboratory, reveals how this yeast can adapt its cellular structure based on nutrient availability. Under conditions of nutrient abundance, H. werneckii cells multiply and remain connected, forming multicellular aggregates. Conversely, when nutrients are scarce, these cells separate and live independently, facilitating movement through water to find new nutrient sources. This dual lifestyle may provide a distinct survival advantage in the ever-changing ocean environment.

To uncover the genetic basis for this remarkable adaptability, the research team conducted experiments isolating mutants that lacked switching capabilities. They identified ten essential genes responsible for this transition. Deleting one specific gene rendered the yeast incapable of switching forms, while the deletion of another gene restored its flexibility. This suggests multiple genetic pathways can achieve similar outcomes.

Professor Goshima noted that a protein named Myb1 functions as a master regulator, controlling the shift between unicellular and multicellular states. High levels of Myb1 promote budding and separation, while degradation of this protein in nutrient-rich scenarios encourages the formation of multicellular structures.

Interestingly, some of the genes implicated in this process are typically associated with spore formation in fungi, indicating that H. werneckii has repurposed these genes to facilitate its unique switching ability. This phenomenon of gene recycling may represent a common evolutionary strategy for the development of new traits.

The researchers also found that strains of H. werneckii predisposed to multicellularity were predominantly located on the surfaces of marine organisms such as sponges and corals, which are nutrient-rich environments. They hypothesize that forming multicellular bodies helps the yeast anchor itself in favorable locations while resisting the force of water currents. Laboratory tests supported this theory; when exposed to simulated water flow, the multicellular strains clung to surfaces, while their unicellular counterparts were washed away.

In their analysis, the team explored related yeast species and discovered that the genetic mechanisms for switching are not universally conserved. While some species, like Neodothiora pruni, can also alternate between single and multicellular forms, other species have either lost this ability or evolved alternative mechanisms entirely.

Professor Goshima emphasized the evolutionary significance of their findings, stating, “What we achieved was controlling unicellularity and simple multicellularity. The next logical step is to explore how simple multicellularity might evolve into more complex structures.” The ease with which mutations can either eliminate or restore cellular flexibility suggests that transitions between unicellular and multicellular forms may have occurred repeatedly throughout evolutionary history.

The research on H. werneckii not only enhances our understanding of evolutionary biology but also serves as a valuable model for scientists investigating the origins of multicellular life. Professor Goshima remarked, “The ability to switch between single cells and multicellular forms may have been an evolutionary stepping stone before organisms became permanently multicellular.” This groundbreaking study paves the way for future research into the complexities of life’s evolutionary pathways.