A surprising discovery by Japanese scientists reveals that a gene essential to root formation in modern plants has been shaping plant organs since long before roots even existed — rewriting what we thought we knew about plant evolution.
Key Points at a Glance
- The RLF gene regulates root development in vascular plants like Arabidopsis.
- RLF is also active in liverworts, ancient land plants that lack roots.
- The gene functions interchangeably across distant plant species.
- This suggests evolution repurposed an ancient mechanism for new roles.
- The RLF protein’s heme-binding capacity may be central to organ development.
Even the most unassuming plant life on Earth can tell a story that stretches back hundreds of millions of years. A recent breakthrough from Kobe University does just that — revealing that a gene instrumental in root development has a much older origin and broader role in shaping plant organs than previously thought.
The research team, led by plant biologist Hidehiro Fukaki, discovered that a gene called RLF, known to regulate lateral root development in the model plant Arabidopsis thaliana, is also active in liverworts — simple land plants that lack true roots altogether. This suggests that RLF predates the evolution of roots and was later co-opted by evolution for this novel function.
Liverworts such as Marchantia polymorpha represent some of the earliest land plants. Their minimalist anatomy and primitive features make them ideal for studying the foundations of plant biology. When the Kobe team silenced the RLF gene in liverworts, the results were dramatic: organ malformations emerged, revealing that the gene plays a crucial role even in these ancient species.
The real surprise came when researchers swapped the genes between species. The Arabidopsis version of RLF worked flawlessly in liverworts, and vice versa. “This shows that the two genes are functionally interchangeable as actors in organ development,” explained Fukaki, emphasizing their deep evolutionary conservation.
What makes RLF even more fascinating is its biochemical nature. It encodes a heme-binding protein — a member of the cytochrome b5 family — typically associated with electron transport and energy regulation. This is the first time such a protein has been shown to guide organ development in plants. That finding alone could spur new research into the intersection between bioenergetics and morphogenesis.
According to Fukaki, RLF’s versatility highlights a recurring theme in evolution: nature often adapts existing components for entirely new purposes. In this case, a molecular system originally tuned to fundamental cellular tasks may have been repurposed to shape plant anatomy over eons.
The implications extend far beyond plant biology. Understanding how ancient genes like RLF are reused can help scientists unravel similar processes in other organisms — including humans. It’s a reminder that evolutionary innovation isn’t always about inventing something new; sometimes it’s about creatively reusing what already works.
The research was published in New Phytologist under the title “Evolutionary conserved RLF, a cytochrome b5-like heme-binding protein, regulates organ development in Marchantia polymorpha.” The study involved collaboration between Kobe University and institutions across Japan, including Osaka University, Ritsumeikan University, and the University of Tokyo.
As plant science continues to deepen its evolutionary gaze, genes like RLF illuminate the elegant strategies nature employs to engineer complexity — one ancient protein at a time.
Source: Kobe University
