Umeå Scientists Find the Gene That Reshapes Leaf Cells Under Drought
19 October 2026, Sweden: Researchers at Umeå Plant Science Centre in northern Sweden have identified a gene that controls the shape of the puzzle piece like cells covering a leaf’s surface, and found that both the gene’s activity and the cells’ shape change when a tree is placed under drought stress. The discovery, made in European aspen (Populus tremula), adds a new piece to the molecular picture of how trees, and potentially crop plants, physically respond to water scarcity at the cellular level, a question with growing relevance as breeders look for traits that help plants cope with more frequent and severe droughts.
The work was carried out by a team including first author Sijia Liu, along with Siamsa M. Doyle, Kathryn M. Robinson, Zahra Rahneshan, Nathaniel Street and Stephanie Robert, researchers affiliated with Umeå Plant Science Centre, a joint research center of Umeå University and the Swedish University of Agricultural Sciences. The peer reviewed study was published in the journal New Phytologist in September 2026, after the team first posted its findings as a preprint on the repository bioRxiv in January of that year. The Umeå Plant Science Centre’s press release announcing the published version, titled “When aspen trees experience drought, their leaf cells change shape,” was picked up by the botany research newsletter Botany One in early October.
Leaves are covered in so called pavement cells, irregularly lobed cells on the leaf’s outer surface that, viewed under a microscope, interlock like pieces of a jigsaw puzzle. Plant scientists have long suspected that this lobed shape is not just a cosmetic feature but plays a mechanical role, possibly helping the leaf surface manage physical stress as cells expand and contract. The Umeå team’s research points to a specific gene, part of the MYB family of transcription factors, as a key regulator of that shape. Transcription factors are proteins that switch other genes on or off, acting as master control switches inside the cell.
What happens to leaf cells under stress
Under normal, well watered conditions, aspen pavement cells develop their characteristic complex, interlocking shape. When the researchers subjected trees to drought, that complexity broke down and the cells became noticeably simpler and more rounded, a shift the team linked directly to a drop in the activity of the MYB gene they identified. To confirm the gene was actually responsible for the change, rather than simply correlated with it, the researchers used gene editing tools to switch the gene off in some aspen lines and to artificially boost its activity in others. Trees with the gene switched off resisted the drought driven simplification of their leaf cells, while trees engineered to produce extra amounts of it showed the opposite pattern, becoming more sensitive to the shape change. That dosage dependent response, where both too little and too much of the gene’s activity alters the outcome, indicates the gene is finely tuned by the plant rather than acting as a simple on off switch.
The team also examined natural genetic variation across a wild Swedish aspen population and found that trees whose ancestors came from drier parts of the region tended to carry gene variants associated with more complex pavement cell shapes than trees from wetter source areas, a pattern consistent with local adaptation to water availability built up over generations.
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