How Plants Establish and Monitor Root Barrier Integrity: Understanding Lignin Deposition in the Cork

• Applicant: Professorin Laura Ragni, Ph.D.
• Subject Area: Plant Cell and Developmental Biology ; Plant Physiology
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 576709440

Protective barriers isolate the plant from the environment, regulating water loss, gas exchange, nutrient uptake, and preventing pathogen penetration. The endodermis, with its Casparian strips, is the major barrier present in all vascular plants, while the periderm, acting as armor, covers the plant organs that grow radially, such as trunks, branches, and roots. It is a dynamic, multilayer barrier comprising a stem cell niche that divides and differentiates cork layers toward the environment. The deposition of highly specialized biopolymers, such as suberin and lignin, in the cork, confers protective properties to the periderm. Consequently, plants that lack these polymers are more susceptible to drought, heat, and salt stresses, while higher suberin deposition and an increased number of periderm layers correlate with better plant performance. Establishing a root barrier is such a critical event that plants have evolved a surveillance system to monitor barrier integrity and, in case of failure, activate compensatory mechanisms (such as ectopic suberin and lignin deposition) to seal the root. Despite its importance, research into periderm initiation and cork differentiation has only recently begun, and the dynamics of lignin accumulation and the network underpinning the cork surveillance system remain largely unknown. This project aims to elucidate the initial stages of cork differentiation and unravel the signaling hubs monitoring barrier integrity using a cork transdifferentiation system combined with transcriptomic and genetic approaches.

• DFG Programme: Research Grants