QUANTA MAGAZINE - For a molecule of RNA, the world is a dangerous place. Unlike DNA, which can persist for millions of years in its remarkably stable, double-stranded form, RNA isn’t built to last — not even within the cell that made it. Unless it’s protectively tethered to a larger molecule, RNA can degrade in minutes or less(opens a new tab). And outside a cell? Forget about it. Voracious, RNA-destroying enzymes are everywhere, secreted by all forms of life as a defense against viruses that spell out their genetic identity in RNA code.
There is one way RNA can survive outside a cell unscathed: in a tiny, protective bubble. For decades, researchers have noticed cells releasing these bubbles of cell membrane, called extracellular vesicles (EVs), packed with degraded RNA, proteins and other molecules. But these sacs were considered little more than trash bags that whisk broken-down molecular junk out of a cell during routine decluttering.
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About 10 years ago, the molecular geneticist Hailing Jin and her lab at the University of California, Riverside discovered that two organisms from different kingdoms — a plant and a fungus — exchange RNA as a form of warfare. Jin was studying Botrytis cinerea, a fuzzy gray mold that ravages crops such as strawberries and tomatoes, when she saw it swap RNA with the plant Arabidopsis (thale-cress) during infection. The Botrytis fungus delivered RNA that interfered with the plant’s ability to fight the infection. Later work showed that the plant cells could respond with their own volley of RNA that damaged the fungus.