Indiana University Bloomington biologists have found that a wide variety of RNA molecules cover the surfaces of plant leaves. These leaf surface RNA may shape microbial communities. The discovery is reported in the paper titled “Diverse plant RNAs coat Arabidopsis leaves and are distinct from apoplastic RNAs,” which was published in the Proceedings of the National Academy of Sciences on January 3, 2025.

The senior author of the work is Roger Innes, Distinguished Professor of Biology, while the first authors are Meenu Singla-Rastogi and Lucía Borniego, both postdoctoral researchers in the Indiana University Department of Biology.

The study shows that the surfaces of plant leaves contain a large number of RNAs that are unexpectedly stable. According to the study, this stability may be related to the RNAs’ capacity to form condensates with polysaccharides like pectin. These findings highlight how leaf surface RNA may shape microbial communities by influencing microorganisms colonizing these surfaces. The study provides some of the earliest proof that plants may release active RNA onto the surfaces of their leaves, exposing these microorganisms to plant RNA.

Potential Role of RNA in Shaping Microbial Communities

The study suggests that the RNA on leaf surfaces may influence microbial populations by affecting microbial gene expression. According to Roger Innes, plants may use cross-kingdom RNA interference (RNAi), a kind of gene regulation in which short RNAs from one organism base-pair with and regulate the expression of genes in another to control their microbiomes.

This discovery implies that interactions between microbial communities and plant RNA affect the ecosystems on leaf surfaces. This control may determine which bacteria thrive on the leaves, potentially impacting the plant’s health and how it interacts with its environment.

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Implications for Broader Biological Systems

Beyond plants, environmental RNA may also influence microbial populations. Similar mechanisms could occur in the human gut, where RNA released by intestinal epithelial cells may affect gut microbiomes, according to Roger Innes. This highlights the broader implications of how leaf surface RNA may shape microbial communities and influence ecosystems beyond the plant realm.

Innes also hypothesized that RNA found on the surfaces of edible plants, such as salad leaves, may impact human gut microbiomes.

Madison McGregor of the Donald Danforth Plant Science Center, Patricia Baldrich and Blake C. Meyers of the University of California, Davis, and Megha Hastantram Sampangi-Ramaiah and Hana Zand Karimi of Indiana University are among the other authors of the work.

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