Root Exudation and Rhizosphere Biology: Multiple Functions of a Plant SecondaryMetabolite - Communication in Plants: Neuronal Aspects of Plant Life - page 406

Fig. 27.1. A schematic depiction of the potential roles of (±)-catechin in Centaurea mac-
ulosa root exudates. (±)-Catechin is a potent phytotoxin with negative effects on survival
and growth of interspecific competitors of C. maculosa (Bais et al. 2002, 2003). Reduced
competitor growth owing to (±)-catechin exudation increases C. maculosa growth (Ride-
nour and Callaway 2001). Higher catechin concentrations lead to inhibition of C. maculosa
seedling establishment (i.e., autoinhibition), perhaps serving as a mechanism for regulation
of population density (Perry et al. 2005b). (+)-Catechin is antibacterial and antifungal, while
(-)-catechin is nematocidal, perhaps leading to changes in pathogen and mutualist popu-
lations (Bais et al. 2002; Veluri et al. 2004b). Finally, (±)-catechin is a strong metal chelator
with the potential to increase phosphorus and micronutrient availability (Callaway and
Ridenour 2004). (±) Effects of catechin on nematode populations and perhaps mycorrhizal
fungi may also alter nutrient cycling and other soil processes