15
1
Toxic
a
b
c
Nucleus
Vacuole
Cytoplasm
*
. Fig. 1.3 Plants can avoid auto-toxicity of defence compounds by spatial separation between inactive
precursors and activating enzymes. a Inactive precursors are kept in a different cellular compartment,
e.g. vacuole, apart from the activating enzyme. b Inactive precursors are stored in specialized cells
that are dispersed within the normal tissue. c Upon feeding by herbivores, the cells/compartments get
destroyed, their content is mixed and the defence compound is produced
Take-Home Message
5 Plants are a rich source of secondary metabolites, mostly small metabolic compounds that are not involved in basic cellular functions but provide special
traits.
5 Important roles of secondary metabolites include (i) protection against harmful environmental conditions, (ii) protection against pathogens and herbivores,
(iii) feeding deterrence and (iv) attraction of pollinators and seed dispersers.
1.3 · Overview of the Function of Secondary Metabolites in Plants (Details in Part IV)