Lignins and Abiotic Stresses

Lignins, major components of the vascular plant cell wall, provided the mechanical support that allowed the development of upright plants adapted to a terrestrial habitat. Their biosynthesis through the phenylpropanoid and monolignol pathways has been extensively studied and significant advances have recently been made in understanding the regulation of this process. Lignin deposition is also modified in response to both abiotic and biotic stresses. Here, we present an overview of lignin biosynthesis in response to various abiotic stresses: drought, salinity, heavy metals, wounding, low temperature, ozone, UV-B radiation, light, elevated CO2 and nitrogen stress. Although the stimulation of the phenylpropanoid pathway is a common feature of stress response, the subsequent synthesis of lignin is only demonstrated in some cases. The roles of lignins in different phases of abiotic stress response are discussed as well as the regulation of their synthesis under stress.