PLANT-CELL WALL REINFORCEMENT IN THE DISEASE RESISTANCE RESPONSE - MOLECULAR COMPOSITION AND REGULATION

The disease-resistance response of plant cells is composed of a multit ude of biochemical events, and the activation of one of these, the phe nylpropanoid metabolism, is pivotal for the survival of cells under st ress conditions. The basic features of this facet of the disease-resis tance response are beginning to be unraveled in model plant cell cultu re systems. These studies revealed a novel, alternative pathway for th e synthesis of cell wall bound hydroxycinnamoyl esters and lignin. The investigations have, therefore, set the stage for a detailed analysis of the induction process that includes fast, posttranslational activa tion mechanisms as well as de novo enzyme synthesis. The biosynthesis of phenolic compounds destined for the cell wall is considered to reac h far beyond the mere physical strengthening of the cells and includes additional functions, e.g., the release of antimycotic hydroxybenzald ehydes, which are vital for stress compensation.