Lignins – the complex molecules that make plants sturdy and allow them to grow tall – are not as random as once thought. A new international study led by Prof. Edouard Pesquet at Stockholm University uncovers how lignins' chemistry and structure vary between cell types to meet plants' physiological needs. The paper, published as a Tansley Review in the journal New Phytologist, highlights how this molecular diversity has been key to plants' success on land.
Prof. Pesquet is a researcher at the Department of Ecology, Environment and Plant Sciences at Stockholm University and the Bolin Centre for Climate Research. Co-author Prof. Katharina Pawlowski, also based at the same department at Stockholm University and the Bolin Centre, contributed expertise on plant physiology and symbiotic interactions.
"Our work combines detailed structural analyses of lignins with insights into their structure-specific physiological functions," says Prof. Pawlowski.
Without lignins, there would be no trees, ferns, or flowering plants—only mosses. Lignins strengthen plant cell walls, enabling water transport, UV protection, and defense against pathogens. They also store an estimated 25–30% of all biological carbon on Earth.
The study, conducted in collaboration with researchers from the University of São Paulo (Brazil) and the Tokyo University of Agriculture and Technology (Japan), synthesizes decades of research to clarify how lignins form and function. It shows that the specific spatial distribution and chemical composition of lignins in each cell type determine how effectively plants grow and adapt to their environment.
"Although we know that different cell types synthesize structurally distinct lignin polymers, it is only recently that their unique physiological roles have become clear," says co-author Prof. Igor Cesarino at the University of São Paulo. "Our review critically assesses how lignin chemistry underpins plant development and environmental responses."
The comprehensive review also includes a glossary of lignin terms, a proposed revised nomenclature for lignin chemistry, and an in-depth look at lignins from their molecular structure to their genetic regulation and physiological roles.
"The diversity of lignin structures reflects the many adaptative processes plants have made over their long evolutionary history," adds co-author Prof. Shinya Kajita from Tokyo University of Agriculture and Technology.
