Gains achieved by molecular approaches in the area of lignification

In this article we highlight the contribution of molecular biology and lign in genetic engineering toward a better understanding of lignin biosynthesis and spatio-temporal deposition of lignin. Specific examples from the liter ature and from our laboratory will serve to underline the chemical flexibil ity of lignins, the complexity of the regulatory circuits involved in their synthesis, and the specific behavior of different cell types within the xy lem. We will also focus on strategies aiming to reduce the lignin content o r to modify the lignin composition of plants and present their impact on pl ant development. We will show that the ectopic expression of a specific tra nsgene may have a different impact, depending on the genetic background, an d that plants with a severe reduction in lignin content may undergo normal development. Lignification is currently benefiting enormously from recent d evelopments in molecular biology and transgenesis, and the progress made op ens the way for future developments to study how the walls of lignified pla nt cells are built and organized.