Scientists identify genetic mechanism responsible for plant leaf diversity

Plant leaves come in many different shapes, sizes, and complexities. Some leaves are large and smooth, while others are smaller and serrated. Some leaves grow in single pieces while others form multiple leaflets. These variations in leaf structure play a crucial role in how plants adapt and survive in different environments.

“Plant morphology is diverse in nature,” said Zhongchi Liu, professor emeritus in the department of cell biology and molecular genetics at the University of Maryland. “Morphological differences contribute to the survival of plants, particularly in their ability to regulate their temperature and in their ability to transport water from their roots to the rest of their body.

“Understanding the mechanisms responsible for the various leaf shapes will provide insight into how plants can survive harsh conditions.”

In an article published in January 2024 in the journal Current biology, Liu’s lab identified two key regulatory pathways involved in leaf development across three types of strawberry plants with different leaf structures. Driven by genes expressing the distinct complexity of each plant’s leaves (a single piece or multiple leaflets) or the characteristics of the margins (smooth or jagged edges), the two pathways took turns to shape leaves over time.

This link between the timing of the impacts of these pathways on plant development and the diverse leaf structures that result could be used to help plants adapt to or tolerate a wider range of conditions and environments, depending on the researchers.

“If we can adjust this relationship, we can make strawberries produce greater biomass, which could potentially support greater fruit production,” explained Xi Luo, lead author of the paper and postdoctoral associate of the department of cell biology and molecular genetics at UMD.

“We can also take these strawberries somewhere beyond their native habitat and increase their adaptability by changing the morphology of their leaves. More serrations mean they will have greater resilience to cold, for example. And Wider, smoother leaves may mean they will be better at surviving in warmer locations.

Liu’s team found that both pathways impacted strawberry plants at different stages of development. For example, the pathway governed by the gene that expresses leaf complexity may dictate that a strawberry plant develops single-leaf formations rather than its usual trifoliate (three-part) growth pattern.

As the plant matures, the pathway governed by the gene that expresses the margin trait may inhibit the CUC2 gene (responsible for plant cell growth and division) and limit the depth of leaf serrations. As a strawberry plant grows, pathways work together to activate or inhibit the CUC2 gene, resulting in plants with diverse shapes, which can increase a strawberry plant’s chances of survival.

The researchers’ findings aren’t limited to strawberries, however. Experiments with Arabidopsis (a small flowering plant related to cabbage and mustard) showed similar regulation of leaf margin characteristics, suggesting that these formation mechanisms could also apply to many other plants.

Understanding how plants control the shape of their leaves gives scientists and farmers new tools to help plants resist heat and other weather conditions and conserve water more efficiently. This brings scientists closer to preparing the world for the challenges posed by climate change.

“Research like this has many implications for our conservation and agricultural efforts,” Luo said. “We are now better equipped to protect our natural resources and food supply from extreme conditions.”