Plant leaves may look unassuming, but behind their shiny surfaces lies a surprising discovery: They’re coated in a variety of RNA (ribonucleic acid) molecules.
This discovery has the potential to reshape our understanding of plant biology and the interactions between plants and their environment.
The study was led by Lucía Borniego and Meenu Singla-Rastogi, postdoctoral fellows at Indiana University Bloomington, along with Roger Innes, professor of biology.
The research offers new insights into the complex relationships between plants and microbes. “What excites us most about this discovery is that it indicates that plants can control their microbiomes, in part, by regulating gene expression in microbes using cross-kingdom RNA interference, also known as RNAi,” Innes said. But what does this mean, and why is it significant?
Breakthrough Discovery: Plant RNAs on the Surface of Leaves
RNA, a fragile molecule, normally degrades rapidly outside a cell unless protected. However, this study reveals that plants secrete viable RNA onto their leaf surfaces, where it remains surprisingly stable. This
finding suggests that plant-derived RNA can directly influence microbial communities on leaf surfaces by engaging in cross-kingdom RNAi—a process by which RNA from one organism affects gene expression in another.
Cross-kingdom RNAi is not new to biology. Scientists have known that organisms can exchange RNA to regulate genes. What’s remarkable here is the idea that plants might use this mechanism to interact with microbes that are colonizing their surfaces.
“It has only recently been shown that RNAs produced by one organism can be taken up by another organism and then base pair with RNAs in the recipient organism,” Innes explained. RNA interference appears to occur in nearly all living organisms.
Role of RNA and polysaccharides in plants
The research team found abundant RNAs on the leaf surfaces of Arabidopsis thaliana , a model plant widely used in scientific studies.
These RNAs were stable, probably because they formed condensates with polysaccharides such as pectin. As a component of the plant cell wall, pectin appears to play a protective role, ensuring that RNA molecules can persist outside of plant cells.
The implications are profound. Stable RNA on leaf surfaces means that microbes colonizing these areas are exposed to plant RNA. This exposure can influence microbial gene expression, potentially determining which microbial species can thrive on leaf surfaces.
This ability to “curate” microbial communities could impact plant health, disease resistance, and overall growth.
Why does this matter? The big picture
The implications of this research extend far beyond plants. “Manipulation of microbial communities by environmental RNA is likely occurring in our own guts as well, with RNA being secreted by our intestinal epithelial cells,” Innes noted.
This means that understanding the interactions between plants and microbes could shed light on similar processes in humans and other animals.
The connection doesn’t end there. Think about the salad you ate for lunch. The RNA on the surface of those leafy greens could interact with your gut microbiome, influencing its composition and, potentially, your health.
While this hypothesis requires further research, it opens up fascinating possibilities for how our diets could directly impact our microbial ecosystems.
Potential applications in agriculture and medicine
This discovery isn’t just a scientific curiosity; it could have real-world applications. If plants can use RNA to influence microbial communities, farmers could one day harness this ability to improve crop health.
For example, plants could be genetically engineered to secrete specific RNAs that deter harmful microbes or promote beneficial ones.
In medicine, understanding how RNA influences microbial ecosystems could lead to new therapies. Imagine using RNA-based treatments to modulate the gut microbiome in patients with digestive disorders or metabolic diseases.
While such applications are speculative, the foundation laid by this study provides a roadmap for possible future explorations.
Call for more research on plant RNA
While this study provides valuable insights, it also raises new questions. How do specific RNAs influence microbial gene expression? Are there specific microbes that are more susceptible to RNA interference? And what environmental factors affect the stability of RNA on plant surfaces?
Furthermore, the potential interaction between plant RNAs and the human microbiome deserves closer examination. Could the consumption of RNA-coated plants have measurable effects on human health?
Future research will need to address these questions to unlock the full potential of these discoveries.
A window into nature’s complexity
This discovery reminds us of nature’s intricate complexity. From the stability of RNA on plant surfaces to its potential to shape microbial communities, the study offers a glimpse into the complexity of hidden genetic mechanisms.
The research also highlights the interconnectedness of life on Earth—how plants, microbes, and even humans are linked by molecular interactions that transcend species boundaries.
“It’s quite possible that RNA on the surface of leaves, like in salad greens, could influence our own gut microbiomes,” Innes said.
This idea challenges us to rethink our relationship with plants, not just as sources of food or oxygen, but as active participants in a dynamic, interconnected biosphere.
The research was a collaborative effort. In addition to the Indiana University team, collaborators included Patricia Baldrich and Blake C. Meyers of the University of California Davis, and Madison McGregor of the Donald Danforth Plant Science Center.
The interdisciplinary nature of this research makes it all the more remarkable. By combining biology, chemistry, and molecular genetics, the team uncovered a layer of plant-microbe interaction that had remained hidden until now.
The study was published in the journal Proceedings of the National Academy of Sciences.
