Chapter 11 - Role of phenolic compounds in adventitious root formation

Abstract

Several endogenous and exogenously applied compounds may promote or inhibit adventitious root formation. Among these factors, phenolic compounds, the most important secondary metabolites in plant organisms, are involved in various physiological processes during rhizogenesis. Some phenolic compounds improve the auxin stimulus and act as cofactors to root initiation, either by acting as competing substrates for indole-3-acetic acid (IAA) oxidase or more likely by scavenging the free radicals that catalyze the peroxidase reaction, while several other phenolics act as precursors to lignin formation. On the other hand, monophenols and m-diphenols may have a negative impact on adventitious root formation by stimulating IAA oxidation, while others have no regulatory effect at all. Therefore, the effect of a specific phenolic compound in rhizogenesis depends on its particular chemical type and its quantitative availability. In the present chapter, the physiological and biochemical role of endogenous phenolic compounds in rhizogenesis is reviewed. Furthermore, the functions and the possible efficacy of the exogenously applied phenolic compounds on several species are presented, and their potential effect on vegetative plant propagation is also discussed.